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Teat and Udder Surgery
SOFT TISSUE SURGERY
0749-0720/95 $0.00 + .20
TEAT AND UDDER SURGERY Bruce L. Hull, DVM, MS
ANATOMY
The principal support for the udder is the medial and lateral suspensory ligaments. The medial suspensory ligament is elastic in nature, and although each half of the udder has a medial suspensory ligament, they are tightly adherent to each other. The lateral suspensory arises from the subpelvic tendon and prepubic tendon and is located lateral to the inguinal canal. The two halves of the udder are distinctly separate from each other and are supplied by separate arteries, veins, and nerves. Although the front and rear quarters are separate from each other, as far as secretory tissue is concerned, the secretory tissues of the front and rear quarters interdigitate and cannot be separated from each other, as the halves of the udder can. The front and rear quarters of a given side share a common blood and nerve supply. The main blood supply to the udder is via the external pudendal artery, which courses through the inguinal ring and divides into cranial and caudal mammary arteries. There also is a small perineal artery, but its contribution to the blood supply of the udder is minimal. The udder is drained by the perineal veins, the external pudendal veins, and the subcutaneous abdominal veins. The teat wall is composed of five layers. The inner-most layer is composed of a very thin mucosa followed by the submucosa. The next layer is connective tissue, which is rich in blood supply. External to the connective tissue layer is the muscular layer, composed of both circular and longitudinal muscle fibers. Externally, the teat is covered by stratified squamous epithelium. From the Food Animal Section, Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio
VETERINARY CLINICS OF NORTH AMERICA: FOOD ANIMAL PRACTICE VOLUME 11 • NUMBER 1 • MARCH 1995
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The teat mucosa surrounds a teat cistern that, during lactation, is filled with milk. The teat cistern is continuous proximally with the gland cistern. A distinct annular ring demarcates the teat cistern from the gland cistern (Fig. 1). This annular ring is of significance because it usually contains a large vein that encircles the base of the teat. Located at the distal end of the teat and connecting the teat cistern to the outside is the streak canal (papillary duct). At the junction of the teat cistern and the streak canal is the rosette of Furstenberg. This rosette is created when the mucosa of the teat cistern meets the stratified squamous epithelium of the streak canal. The circular teat sphincter muscle lies directly beneath the rosette of Furstenberg at the proximal end of the streak canal. The streak canal varies from 0.5 to 1 cm in length, and ends externally at the teat orifice. RESTRAINT AND ANESTHESIA
Over the years, many teat surgeries either have not been completed or have been completed in a less than satisfactory manner due to inadequate restraint and anesthesia. Successful outcome depends on meticulous suturing under aseptic conditions. IS Adequate restraint, tran-
Figure 1. The teat cistern, which is separated from the gland cistern by the annular ring, is shown. Note the large vein at the annular ring.
Figure 2. "Web" teat. Note the small bulge on the side of the primary teat. This bulge surrounds the teat sphincter of the web teat.
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quilization (if indicated), and anesthesia are necessary to perform teat and udder surgery in a manner that leads to a successful outcome. For simple procedures such as relieving a "hard milker," tailing the cow up (tail jack or tail hold) may be all that is required. This often can be combined with infusion of a small amount (3-5 mL) of local anesthetic agent into the teat cistern through the streak canal. This infusion anesthetizes the mucosa and submucosa, but is not adequate for repair of a teat laceration. For more complicated procedures, the cow should be restrained in lateral or dorsal recumbency. Although a surgery table provides ideal restraint for teat and udder surgery, one often is not available in a practice situation. General anesthesia occasionally is indicated, but most teat surgery can be performed under heavy tranquilization and a local block. Today, the tranquilizer of choice would seem to be xylazine (0.05-0.1 mg/lb) given intravenously. It should be noted that the use of xylazine in cattle has not been approved by the Food and Drug Administration. Xylazine often causes cattle to become recumbent and the practitioner should be prepared for recumbency if it is to be given. Once down, the animal can be furthe~ restrained with ropes, if indicated. Xylazine alone is not sufficient for teat surgery and a local block with lidocaine or xylocaine generally is used. An intravenous block has been described for anesthesia of the teat but it has not been widely accepted. I8 The local block usually is a ring block placed at the junction of the teat and udder. A volume of 10 mL usually is sufficient and a fine-gauge (23-25) needle is used. This ring block is simple to perform, does not interfere with healing because it is a regional block, and generally is sufficient for most teat procedures. For udder amputation, either general anesthesia or a large (50-100 mL) epidural can be used. 21 This large-volume epidural is necessary both to maintain recumbency and to provide anesthesia to the entire udder.
SUPERNUMERARY TEATS
Supernumerary teats are the most common congenital anomaly in cattle. 4 Supernumerary teats should be removed for cosmetic purposes and to prevent mastitis. This surgery ideally should be performed at 4 to 6 months of age. At this age, the animal is old enough for the practitioner to distinguish which teats are the primary teats and which, indeed, are supernumerary, yet the teats are small enough that bleeding is minimal and the site heals without complication. At this age, supernumerary teats can be removed with a serrated scissors. Teats always should be removed so the resultant cut is craniocaudal in orientation so the resultant scar blends with the normal folds of the udder. If supernumerary teats are large or if they are not removed until an older age, they will need to be damped with an emasculatome at the base of the teat prior to removal. If supernumerary teats are not removed before the animal is
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"springing," they should be dissected surgically or left until the animal is dry because udder edema may interfere with healing. To remove supernumerary teats in the "springer" or during lactation, the animal should be tranquilized and a local block placed. The teat then should be dissected surgically with an elliptical incision (craniocaudal orientation). This dissection should provide visualization of the mucosa of the accessory gland from which the supernumerary teat arose. This mucosa should be closed with a simple continuous suture of fine absorbable suture. The connective tissue should be closed in a similar manner. Last, the skin should be closed with interrupted sutures of nonabsorbable material.
"WEB" TEATS (CONJOINED TEATS)
A supernumerary teat occasionally is attached to the side of a primary teat. When this is the case, it may be visible as a bulge or bump on the side of the primary teat or merely as an extra teat orifice on the side of the teat (Fig. 2). In this case one, first must evaluate the situation carefully to be sure it, indeed, is a supernumerary teat with a separate gland and not a teat fistula connected to the primary teat cistern. This evaluation can be performed best by injecting dye into the orifice of the suspected supernumerary teat and milking the primary teat to check for the presence of dye. The dye normally used is 30 mL of new methylene blue (Fisher Scientific, Fairlawn, NJ). Treatment of a fistula into the teat cistern of the primary teat is the same as that discussed in the section on repair of teat fistula following teat laceration. The amount of secretory tissue in the accessory teat normally is of little or no consequence. If in doubt, one can milk or drain the accessory teat to determine its volume, or ascertain volume with the aid of contrast radiology or ultrasonography. Contrast radiography can be performed by injecting 10 mL of contrast material into the fistula and taking a radiograph of the affected teat and quarter. s, 7 Ultrasonography (if available) probably is the method of choice for evaluation of the udder.6 Surgery is indicated for accessory teats attached to the side of normal teats because incomplete milking of the accessory gland and trauma to its orifice often lead to mastitis, which is difficult to treat and may spread to the primary gland. Surgery usually is accomplished by an elliptical dissection around the mass of the supernumerary teat or, in the absence of a teat, dissection around the orifice (of the accessory gland). This elliptical incision must be parallel to the long axis of the primary teat. Dissection is carried deeper and the teat cistern of the accessory teat carefully is dissected free. This dissection can be aided by a side opening teat cannula inserted into the accessory teat orifice. Care should be used in this dissection to avoid opening the teat cistern of the primary teat~ Once the teat cistern has been isolated, it is removed at its junction with its gland cistern
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(gland cistern of the accessory teat). The wound then is closed in three layers, as described for removal of supernumerary teats in springing heifers or lactating animals. If one finds significant milk in the glandular tissue of the accessory teat, a procedure has been described for connecting the teat cistern of the accessory teat to the gland cistern of the primary teat. 16, 17 Once the teat cistern of the accessory teat has been exposed, as previously described, a side opening teat cannula is inserted into the primary teat and the tissue between the primary teat cistern and the accessory teat cistern is incised for a distance of 2 to 3 cm without entering the annular ring (large vein and excessive bleeding) between the teat cistern and gland cistern. The mucosa of the primary teat and accessory teat are opposed with a simple continuous suture of .4-0 polydioxanone (PDS, Ethic on, Somerville, NJ). Although this step may seem unnecessary, unsutured mucosal wounds of the teat have a strong tendency for excessive granulation tissue. This granulation tissue becomes so excessive it occludes the opening between the two teat cisterns if suturing is not performed. The incision into the teat then is closed in three layers, as described for teat lacerations.
CONGENITAL ATRESIA ("BLIND QUARTER")
Atresia usually is not observed until the onset of lactation. It often is considered to be congenital but it may be caused by trauma before the first lactation. Both trauma from being sucked and infection spread by flies have been mentioned as causes of "blind quarters." The indication of atresia is the heifer that freshens with minimal or no milk from one or more quarters. Atresia can occur in four 10cations-(1) the distal end of the teat (no teat orifice), (2) the teat cistern, (3) at the annular ring (junction of the teat cistern and gland cistern), and (4) fibrosis within the gland cistern. Careful evaluation is essential to determine the cause and extent of the problem. Physical examination, especially careful palpation, often reveals the cause of the problem. If not, contrast radiology or ultrasonography are very useful diagnostic tools. Heifers presenting with atresia should be evaluated with ultrasonography or radiography (contrast or double contrast). Contrast radiography is performed by injecting 10 mL of an iodine-based radiopaque material through the streak canal and into the teat and gland cisterns after aseptic preparation of the teat end. 5, 7 A film then is taken and compared with normal radiographic anatomy. Ultrasonography, if available, probably is more useful in evaluating normal interior teat structure. 6 Again, one must be familiar with the normal in order to interpret the abnormal. We use ultrasonography almost exclusively as the diagnostic tool to evaluate quarters that will not milk, not only in first-calf heifers, but also with "teat spiders"
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to evaluate the extent of the spider and amount of teat cistern wall involved. It should be noted that an obstructive lesion may be present for 6 days with very little, if any, decrease in milk flow for the lactation. After 6 days of obstruction, the gland begins to involute and production from the quarter in question will be decreased for the lactation in question. It should return to normal in subsequent lactations, however, if there is no scar tissue within the gland cistern.
OBSTRUCTION AT THE DISTAL END OF THE TEAT
Obstruction (atresia) at the distal end of the teat often is just imperforate skin. In this case, one often can squeeze the teat and observe a bulge over the area of the teat orifice. This bulge can be opened with a large (12-14) gauge needle or #11 scalpel blade. The end of the teat usually needs to be rolled between the thumb and finger before milking for several days. This serves to break down any small fibrinous adhesions that may be forming and helps keep the teat orifice patent until healing is complete. This surgery usually is very successful.
CONGENITAL OBSTRUCTION OF THE TEAT CISTERN If the teat cistern is obstructed by scar tissue, the amount and location of the scar tissue must be evaluated. In this case, sonography is far more helpful than contrast radiography because the contrast material used in radiography cannot penetrate the scar tissue and the extent of the scar tissue cannot be evaluated fully. If the teat is obstructed by a small bridge of scar tissue, it may be opened or removed through the teat orifice. If the obstruction is more than just a membrane, however, the results obtained through the teat orifice often are disappointing. When opened through the distal orifice and streak canal, a good milk flow is obtained initially, but decreases and eventually ceases over a period of several days. New obstruction may be caused by incomplete removal of the offending scar tissue but usually is due to the formation of excessive granulation tissue. The teat cistern is very prone to granulation tissue formation because the mucosa is very loosely attached and the blood supply is rich. If tissue removal is anticipated, it is advisable to perform a thelotomy. Over the years, there has been a great reluctance on the part of veterinary practitioners to open teats for fear of poor results (dehiscence). This fear is acquired through experience with teat lacerations that do not heal. There is a big difference in healing between a fresh teat incision and an old, contaminated laceration. The use of a thelotomy should not be feared. 2 A thelotomy should be performed parallel to the long axis of the teat and care should be taken to avoid the streak canal and distal 1 cm
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of the teat cistern as well as the annular ring at the base of the teat. Inserting a side-opening teat cannula into the teat cistern, if possible, often is helpful when opening the teat. Once the teat has been opened, the obstruction can be visualized and carefully dissected free. After removing the obstruction, the mucosa must be sutured carefully with 4-0 polydioxanone or polyglactin 910 (Vicryl, Ethicon, Somerville, NJ). If necessary, adjacent mucosa may be undermined and slid to provide closure with minimal tension on the mucosa. 7 If the defect created in removing the scar tissue mass is too large to close with minimal tension on the mucosa, the use of an implant should be considered if indicated economically. Because the use of an implant is not always successful, this possibility should be discussed with the owner prior to surgery and the prosthesis should be available in case it is needed.
TEAT PROSTHESIS
When the teat mucosa cannot be closed completely, it is advisable to place a teat implant. The teat implant consists of a piece of medical grade silastic tubing placed within the teat cistern. This tubing must be long enough to extend up into the gland cistern and the distal end of it must be rounded to minimize trauma to the rosette of Furstenberg and the teat sphincter. This piece of tubing gives the teat mucosa a template to form around, at the same time inhibiting formulation of granulation tissue by pressure. While the teat is open, the silastic tubing is sutured into place with nonabsorbable suture material in the mid teat cistern region. Three sutures usually are placed-one directly opposite the incision and two at 90 degrees from the original suture. These stay sutures should be placed so as to incorporate as much tissue as possible (without penetrating the skin). One of the main complications of teat implants is that they later dislodge and float free. Incorporating large amounts of tissue helps prevent this complication. This method leaves the area of the primary incision free of stay sutures and facilitates incision closure. The length of the silastic tubing to be used is debatable. A long tube that extends well into the gland cistern is less likely to float free over time, but it is more prone to "fracture" over time. At present, it seems advisable to use as long a tube as possible. It also is debatable whether the tube needs to be removed if and when it floats free. My personal preference at this time is to leave it alone unless it causes problems. The portion of the tube that will be within the gland cistern should be fenestrated to allow milk to enter the tube in more than one place. Care should be taken in making these fenestrations to avoid weakening the tube any more than necessary. Once the implant has been placed, the teat is closed in a routine manner, as described in the section on teat laceration. It should be noted that teat implants are only about 50% successful,
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whether used for teat spiders or for scar tissue in first-calf heifers. The failures occur after the implants float free or are removed; at that time, some teats again close with scar tissue. Any evidence of mastitis precludes the use of a teat implant. If one is suspicious that infection may be present or if the owner has attempted milking the cow with a teat cannula, the milk should be cultured before surgery or, if this is impossible, during surgery. Because the teat implant is a foreign body, any mastitis can lead to a disastrous result. OBSTRUCTION AT THE ANNULAR RING If an obstruction at the annular ring is a thin membrane, it can be incised through the streak canal using a sharp, pointed teat bistoury.8 The bistoury is inserted to the membranous obstruction and a large X is made in the membrane. Care is taken to avoid the vascular ring located within the annular ring. If the vascular ring is cut, it often is necessary to open the teat to control the resultant hemorrhage. In the case of a thin membrane, the flaps created by the X-shaped incision fall into the teat cistern and milk flow is obtained. Experience, however, indicates that the obstruction usually is not membranous, but rather a thick piece of tissue. In this case, a thelotomy must be performed and an implant placed if one is to hope for any chance of success. As previously mentioned, if this is the case, the milk must be evaluated for evidence of mastitis and the prognosis must be discussed with the owner.
FIBROSIS WITHIN THE GLAND CISTERN
Although fibrosis within the gland cistern can be suspected by palpation, it can be confirmed only by contrast radiography or, preferably, ultrasonographic evaluation. If fibrosis is detected within the gland cistern during the evaluation, the prognosis for surgical success is hopeless. If milk is not being produced or collected into a gland cistern, no surgical procedure exists at this time that will correct the problem. One should be aware that any congenital obstruction may be accompanied by fibrosis of the gland cistern, so careful evaluation of the entire quarter is necessary before performing any surgery. It is embarrassing to perform a nice piece of surgery to correct an obstruction within the teat cistern only to find out that the quarter does not milk. HARD MILKER (TIGHT TEAT SPHINCTER)
A hard milker usually is caused by trauma to the teat end. This trauma usually is in the form of a crushing injury and often is self inflicted; the cow crushes her own teat between her leg and the floor
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when trying to rise. Other causes for this trauma are poor milking machine function, delivering excess vacuum to the teat end, and frostbite of the teat end. Any traumatic insult to the area of the teat sphincter causes an increase of scar tissue, which leads to a small stream of milk and slow milking. As such, this type of injury often is self perpetuating. Obstructive lesions at the teat sphincter also can occur because of flaps in the area of the rosette of Furstenberg. The typical history is that one quarter takes a lot longer to milk out than the other three quarters. As already mentioned, this longer milking effort increases the trauma to the end of the teat and, in time, may increase the amount of scar tissue and make the cow even more difficult to milk. The trauma to the teat end, coupled with incomplete milking, often leads to mastitis. The traditional owner treatment for the hard milker is the use of a teat dilator, which over stretches the teat sphincter. Teat dilators may be successful, but more often fail or predispose to mastitis. Some types of teat dilators also are brittle and can break off, leading to intramammary foreign bodies which then must be removed. In order to be effective, a teat dilator must be used over a period of several days. Surgical intervention probably is more successful than dilators. There are many surgical instruments in the market specifically designed for the relief of a hard milker. All of these instruments either cut or stretch the teat sphincter. Before considering surgery on the teat sphincter, it is important to realize that the keratin lining of the streak canal is very important in preventing mastitis. Any disruption of this keratin lining (especially a disruption from the top to the bottom of the streak canal) will increase the chance of mastitis until a new keratin layer has been secreted. With this in mind, it probably is not wise to use any instrument that removes the keratin lining or damages it from the top to the bottom. Surgery for a stenotic teat sphincter should be performed before the morning milking so surgical response can be monitored and proper aftercare can be initiated. After surgical preparation of the teat, a teat knife is inserted through the streak canal, using care to avoid cutting the entire length of the streak canal. The knife is angled at 45 degrees and a cut is made at the rosette of Furstenberg (area of the sphincter muscle), and the knife is gently removed from the teat (Fig. 3). The teat is milked forcefully to assess progress. If necessary, the teat sphincter is cut again at 180 degrees from the first cut. Cuts can be repeated at 90 degrees if necessary. Milk flow should be evaluated after each cut. Evidence that the correct amount of cut has been made is provided when the teat drips a fine stream of milk for 1 or 2 minutes after a forceful stream of milk is expelled from the teat. After surgery, the quarter should have several streams of milk expressed every 15 minutes for the next 2 or 3 hours and then once every hour until the next milking. This stripping must be forceful; the goal is to prevent closure of the incisions. It may be necessary to roll the end of the teat between the thumb and finger to break down any fibrinous adhesions starting to form between the cut edges. If the oper-
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Figure 3. The use of the Lichty Teat Knife to open a "hard" milker is demonstrated. The knife is angled so that it cuts the sphincter muscle without cutting the entire length of the streak canal.
Figure 4. Teat "spider." Initially, the hematoma and later the scar tissue bulge into the teat cistern.
ated teat cannot be milked frequently, a dilator may be placed in the streak canal for a day or two. The results obtained with dilators are less satisfactory than frequent stripping. ENLARGED TEAT ORIFICE (DRIPPING MILK)
If one is overzealous in treating the "hard milker" a leaker may develop. Enlarged teat orifices are very difficult to treat. Using a TB syringe and a fine (27 gauge) needle, one can inject a drop of Lugol's iodine at four places (every 90 degrees) around the teat sphincter to create scar tissue in the hope of tightening the teat sphincter, but this often is unrewarding. s TEAT LACERATIONS
The prognosis in teat lacerations depends on several factors and can vary from good to hopeless. Needless to say, full-thickness lacerations (into the teat cistern) have a much poorer prognosis than partial-thick-
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ness lacerations. The fresher a laceration is when repaired, the better it heals. Prognosis drops in lacerations that are more than 4 hours old and, after about 12 hours, the prognosis is extremely poor. Because of the longitudinal blood supply of the teat, vertical lacerations heal far better than horizontal lacerations. Again, because of blood supply, lacerations that are near the base of the teat (its attachment to the udder), heal better than lacerations of the distal teat. Lacerations that involve the teat sphincter and streak canal have a much poorer prognosis than those that do not involve these structures because it is difficult to effect anatomic repair. Before attempting repair, one must clean and thoroughly evaluate the laceration for any small, deep holes that may be covered by a fibrin clot. Even small fistulas change the method of repair and the prognosis. If one is to attempt repair of a laceration of unknown duration or known to be over 4 hours old, extensive debridement is necessary. Any tissue that is infected, necrotic, or devitalized must be removed completely. There is, however, very little "extra" tissue available in the teats of today's dairy cow, so delicate dissection is necessary to remove desiccated tissue but to preserve all the normal tissue possible. Debridement should continue until fresh, bleeding tissue is obtained. Once anesthesia and debridement have been accomplished, suturing with fine (4-0 or smaller) absorbable suture increases the chance of success. If full-thickness lacerations are left to granulate rather than sutured, 60% to 75% will heal by second intention, with fistula formation.lO, 14 In the past few years, thoughts on the suture pattern for teat lacerations seem to have changed greatly. It seems that the mucosa should be sutured with a simple continuous pattern using fine (4-0 or 5-0) absorbable suture material with a swedged atraumatic needle. 12 The mucosa must be sutured carefully to obtain a milk-tight seaL After completely closing the mucosa, it is helpful to insert a teat cannula through the teat sphincter and gently "probe" the suture line to check for holes or weak areas. If the mucosa is not sutured, granulation tissue proliferates into the lumen of the teat cistern and later obstructs milk flow. 19 When biting full thickness in the mucosa, one is more certain to completely seal the mucosa and prevent milk fistulas. Because the mucosa is very thin and delicate, it should be supported by another simple continuous layer of fine absorbable suture placed in the submucosa. The remainder of the teat wall then should be closed with vertical mattress sutures of a noncapillary materiaL Vetafil (Bengen Company, Hanover, Germany) or Braunamid (B. Braun, Melsungen, Germany) are ideal sutures for this. The deep bite of the vertical mattress is placed adjacent to the submucosal suture line to give it support, whereas the shallow bite is very superficiaL Using this suture technique, we have successfully put cows back on machine milking at the next scheduled milking.12 Previously, Larson's teat cannulas have been used to achieve milk out. It now is recognized that the use of cannulas to drain the quarter is contraindicated because it increases the risk of mastitis and may damage the repair? Another approach used in the past was to not milk for 4 or
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5 days. Although this was not detrimental to production, it did greatly increase the tension on the suture line. It recently has been advocated that tissue adhesives be used to repair teat lacerations. 10, 14, 19 From the research that has been done, it appears that tissue adhesives give very satisfactory healing results. Research also has shown that tissue adhesives cause a rather severe tissue reaction, characterized by a marked foreign body reaction.lO In addition, it has been shown that, if tissue adhesives are to be used, they should be used independently and not in combination with suture material. 14 In the normal course of events, the tissue adhesive is extruded as healing takes place. Suturing in conjunction with tissue adhesives prevents this extrusion and increases the foreign body reaction.
Special Care Teat Lacerations If a non-full-thickness horizontal laceration results in a ventrally based skin flap, the blood supply should be evaluated carefully. If the blood supply is inadequate, the flap should be trimmed to healthy tissue. The remaining wound may be closed in some cases or left to granulate if the remaining tissue is inadequate for closure. A teat occasionally is stepped on in such a manner that the teat sphincter is totally separated from the surrounding skin. Upon examination of this wound, it appears that there is no teat sphincter and the end of the teat is raw. Closer examination reveals that, in reality, a large hematoma is held in place by a flap of skin and the teat sphincter and streak canal are recessed above this hematoma. This type of laceration is painful, difficult to manage, and often leads to mastitis. Although it seems radical, the best way to handle these lacerations is to remove all of the undermined skin with a pair of sharp scissors.13 When removing the skin, one should exercise caution to avoid the teat sphincter and streak canal. Although this leaves a raw teat end, the resultant lesion is much less painful than the undermined skin and hematoma. In addition, this procedure greatly reduces the risk of mastitis. The resultant wound is treated as an open wound and allowed to heal by second intention.
Teat Laceration Aftercare
Any full-thickness teat laceration or one that damages the teat end should be treated as if it were a case of mastitis. Culture and sensitivities probably are indicated and, certainly, appropriate antibiotics should be employed, both intramammary and systemically. Care should be taken with intramammary infusion to avoid damage to the repair. Because the teat has an excellent blood supply, skin sutures can be removed in 10 days.
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TEAT FISTULA
Although teat fistulas may be congenital, they usually follow the unsuccessful repair of a teat laceration or are the end result of a laceration in which no repair was attempted. When attempted repair fails, the laceration should be allowed to granulate until the swelling and infection subside. This usually takes 2 to 4 weeks. While waiting, the wound should be cleaned daily and mastitis prevention should be instituted. Once the wound has granulated to an end-stage fistula, surgery should be performed to correct the fistula. After preparation and a ring block, the entire fistulous tract is dissected out. The fistula is dissected out with an elliptical incision around the fistula that is parallel to the long axis of the teat. This dissection must be carried down all the way into the teat cistern, exposing healthy teat mucosa. Once the dissection has been completed, the resultant hole is closed as described for teat lacerations (three-layer closure). TEAT SPIDER
A teat spider can be defined as a mass of scar tissue protruding from the mucosal surface of the teat and into the teat cistern (Fig. 4). It usually is caused by an injury and initially is a large hematoma that causes the loosely attached mucosa to bulge into the teat cistern. This hematoma later organizes into scar tissue and the mass of scar tissue impedes milk flow through the affected teat. Teat spiders traditionally have been extracted through the streak canal. Certainly, for pedunculated masses or free floating masses of scar tissue, this probably is still the method of choice. In working with mural plaques of scar tissue, however, the end result after using a Hugg's tumor extractor (Jorgensen Laboratories, Loveland, CO) or a Cornell teat curette (Jorgensen Laboratories, Loveland, CO) often is worse than the initial obstruction. 2o With pedunculated teat spiders, one can palpate the mass within the teat cistern and, by working through the streak canal with an alligator forceps, the mass can be grasped, broken loose from its stalk, and extracted through the streak canal (while squeezing the teat above to help force the fibrotic mass out with hydrostatic pressure at the same time). If the pedicle already has broken and the mass of scar tissue is floating free within the lumen of the teat cistern, it can be removed in a similar fashion. When the teat spider is a mural-like plaque, the traditional method has been to remove it through the streak canal with various curettes or tumor extractors. The teat mucosa is very loosely attached and has a rich blood supply. These two factors make it especially prone to the formation of granulation tissue. Although removal of a plaque of scar tissue through the streak canal often is successful initially, in many cases it later (2-3 days) obstructs with granulation tissue and milk flow ceases again. It therefore probably is preferable to open the teat (vertically) on
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the side opposite the scar tissue mass. The mass of scar tissue then can be gently dissected free and the mucosa over the defect closed with a simple continuous layer of fine absorbable suture material. 1 If the mucosa is difficult to close, it can be undermined before closure, as mentioned in the section on scar tissue obstruction. Also, as with congenital obstructions, if the mucosa cannot be closed, the use of an implant should be considered. This approach (thelotomy) allows for careful inspection of the teat, meticulous dissection, and hemostasis. After closing the defect, the primary incision is closed in three layers in the same manner as for any other teat laceration. There seems to be a lot of reluctance to approach teat spiders in this manner, for fear of primary wound dehiscence. The reference point for most bovine practitioners is the fact that many teat lacerations do not heal well, but fresh, noncontaminated vertical teat incisions heal very well. TEAT AMPUTATION
Teat amputation usually is performed in cases of irreversible damage to the teat, which may be caused by gangrenous mastitis or severe trauma. In cases of gangrenous mastitis, the teat may be amputated without use of an anesthetic agent. In the case of severe trauma, the teat must be blocked (ring block) before amputation. An emasculatome should be placed across the teat at the junction of the proximal and middle thirds. This avoids the vascular ring at the annular ring and provides good hemostasis to the distal teat. The teat then is dissected sharply distal to the emasculatome. Some recommend opening the teat cistern to provide better drainage of the gland cistern. If this is the case, it is advisable to suture the mucosa to the skin with overlapping horizontal mattress sutures to help ensure hemostasis. Although the quarter will continue to secrete milk for a period of time (except in cases of gangrenous mastitis), it will dry up due to secondary infection and mastitis. Some prefer to try to dry the quarter off before teat amputation, but that usually is difficult because the damage to the teat is too severe to retain the sclerosing agents within the udder. UDDER AMPUTATION
Udder amputation is indicated in individuals of extremely valuable genetic potential with chronic mastitis that is debilitating enough to render them unsuitable for embryo transfer. Although udder amputation has been suggested as a treatment for toxic mastitis, that is not a good application for this procedure. Udder amputation should be performed after mastitis has been treated and the udder is in a state of remission, if at all possible. Experience has shown that removal of actively infected udders results in a much lower success rate, so vigorous medical therapy should be undertaken before surgical intervention in any potential case of udder amputation.
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After the decision has been made to amputate the udder and the animal is a good surgical candidate, one must decide on an anesthetic regime. Although amputation of udders has been described using a large volume epidural (50-100 mL),3 it probably is preferable to amputate udders under general anesthesia, if at all possible. It also is recommended that a blood donor be available or even that blood be drawn and banked for a transfusion in case it is needed. This recommendation probably is more applicable to the bovine than to the ovine or caprine. If possible, the animal should be positioned in dorsal recumbency. This facilitates working on both sides of the udder. If dorsal recumbency is not possible, the animal will need to be rolled from one side to the other during surgery and the appropriate preparations should be made. The external pudendal artery should be ligated before any of the venous system is ligated. This gives the blood in the udder some chance to drain back into the circulation before the udder is removed. A skin incision is made parallel to the base of the udder and about 3 to 5 cm ventral to the dorsal edge of the mammary tissue. This incision eventually extends completely around the udder in an elliptical manner. Hemorrhage should be controlled by cautery or ligation. -Once through the skin, the incision is carefully extended through the lateral suspensory ligament of the udder. Care should be taken because the external pudendal artery and vein lie directly beneath the lateral suspensory. The external pudendal artery and vein can be found coursing from the inguinal ring in a tortuous manner to the juncture of the front and rear quarters of the udder, where both the artery and vein bifurcate. They should be ligated as they exit the inguinal ring and before they bifurcate. It has been recommended that the artery and vein be separated from each other and ligated separately. If this is attempted, extreme care must be taken during this procedure. In practice, the artery and vein often are ligated together. This certainly leaves the possibility of an arteriovenous shunt, but in reality, that rarely occurs. Once the artery and vein have been ligated on one side, the procedure should be repeated on the opposite side unless a hemimastectomy is being performed. At this point, the incisions (each side) are extended anteriorly and the subcutaneous abdominal veins are ligated. It should be noted that although textbooks and articles report that there is one subcutaneous abdominal vein for each half of the udder, in reality, these veins have multiple branches as they approach the udder.l1 Each branch must be double ligated individually. Once the subcutaneous abdominal veins have been ligated, the skin incisions are extended posteriorly and the perineal veins are ligated. There should be one perineal vein on each side, although this is somewhat variable. After ligating all the major vessels, the median suspensory ligament is cut near the body wall. Ideally, about 1 to 2 cm of medial suspensory should remain on the body to give a place to anchor the skin and help obliterate dead space during closure. If only a hemimastectomy is being performed, the right and left half of the median suspensory ligament
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can be separated and only the half of the median suspensory involved with the amputated half is severed. Once the udder has been amputated, the skin is closed. In performing the skin closure, the dead space is obliterated, if possible. This usually includes taking bites of the median suspensory ligament as the skin is closed. Postoperatively, we should hope for first-intention healing, although second intention seems to be more common. Although umbilical tape has been recommended in the literature as the ligature of choice, postoperative infection is much less of a problem if absorbable ligatures are used. If absorbable sutures are used, one should be aware of the large vessels that are being ligated and appropriately sized suture should be used.
References 1. Aher VD, Bhokre AP, Usturge SM: Open teat surgery in bovine and caprine. Indian Vet J 67:469-471 2. Arighi M, Ducharme NG, Horney FD, et al: Invasive teat surgery in dairy cattle, II. Long-term follow-up and complications. Can Vet J 28:763-767, 1987 3. Brewer RL: Mammary vessel ligation for gangrenous mastitis. J Am Vet Med Assoc 143:44-45, 1963 4. Bristol DG: Teat and udder surgery in dairy cattle-Part I. Compendium 11:868-873, 1989 5. Bristol DG: Teat and udder surgery in dairy cattle-Part II. Compendium 11:983-988, 1989 6. Cartee RE, Ibrahim AK, McLeary D: B-Mode ultrasonography of the bovine udder and teat. J Am Vet Med Assoc 188:1284-1287, 1986 7. Ducharme NG, Arighi M, Homey FD, et al: Invasive teat surgery in dairy cattle, I. Surgical procedures, and classification of lesions. Can Vet J 28:757-762, 1987 8. Fox FH: Teat surgery. Iowa State University, Iowa Veterinarian, November-December, 1966, pp. 22-24 9. Gaymer J: The use of tissue adhesives in teat surgery. In Proceedings of the 16th Bovine Practitioner, Stillwater, OK, 1984, pp 175-176 10. Gaymer J, Watson WL, Coy CH, et al: Healing of experimentally induced wounds of mammary papilla (teat) of the cow: Comparison of closure with tissue adhesive versus nonsutured sounds. Am J Vet Res 45:1979-1983, 1984 11. Guard WF: Surgical Principles and Techniques. Columbus, OH, WF Guard, 1953 12. Hull BL: Teat and udder surgery. In Proceedings of the Annual Veterinary Surgery Forum, Chicago, IL, 1985, pp 67-71 13. Lloyd K: Teat end injuries-A surgical procedure. Agri Practice, 1994 14. Makady FM, Whitmore HL, Nelson DR, et al: Effect of tissue adhesives and suture patterns on experimentally induced teat lacerations in lactating dairy cattle. J Am Vet Med Assoc 198:1932-1934, 1991 15. Modransky P, Welker B: Management of teat lacerations and fistula. Vet Med 88:9951000, 1993 16. Rijkenhuizen ABM, Hemeth F: Een chirurgische behandeling voor twee met elkar vergroeide spenen. Tijdschr Diergeneeskd 109:389-393, 1984 17. Shappell KK, Schneider T: Surgical treatment of accessory teat and gland complexes in three cows. J Am Vet Med Assoc 195:623-626, 1989 18. Surborg VH: Regionale Intravenose Anasthesie in der Zitzenchirugie des Rindes. Dtsch Tierarztl Wschr 87:333-335, 1980 19. Tulleners E, Hamir A: Effects of teat cistern mural biopsy and teatoscopy stab versus
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longitudinal incision with or without tube implant on incisional healing in lactating dairy cattle. Am J Vet Res 51:1257-1266, 1990 20. Weaver AD: Teat surgery in cattle. Veterinary Annual 107-112, 1982 21. Wright JG, Hall LW: Veterinary Anaesthesia and Analgesia, ed 5. Baltimore, Williams and Wilkins, 1961
Address reprint requests to Bruce L. Hull, DVM, MS Department of Veterinary Clinical Sciences The Ohio State University College of Veterinary Medicine 601 Vernon L. Tharp Street Columbus, OH 43210-1089
0749-0720/95 $0.00 + .20
TEAT AND UDDER SURGERY Bruce L. Hull, DVM, MS
ANATOMY
The principal support for the udder is the medial and lateral suspensory ligaments. The medial suspensory ligament is elastic in nature, and although each half of the udder has a medial suspensory ligament, they are tightly adherent to each other. The lateral suspensory arises from the subpelvic tendon and prepubic tendon and is located lateral to the inguinal canal. The two halves of the udder are distinctly separate from each other and are supplied by separate arteries, veins, and nerves. Although the front and rear quarters are separate from each other, as far as secretory tissue is concerned, the secretory tissues of the front and rear quarters interdigitate and cannot be separated from each other, as the halves of the udder can. The front and rear quarters of a given side share a common blood and nerve supply. The main blood supply to the udder is via the external pudendal artery, which courses through the inguinal ring and divides into cranial and caudal mammary arteries. There also is a small perineal artery, but its contribution to the blood supply of the udder is minimal. The udder is drained by the perineal veins, the external pudendal veins, and the subcutaneous abdominal veins. The teat wall is composed of five layers. The inner-most layer is composed of a very thin mucosa followed by the submucosa. The next layer is connective tissue, which is rich in blood supply. External to the connective tissue layer is the muscular layer, composed of both circular and longitudinal muscle fibers. Externally, the teat is covered by stratified squamous epithelium. From the Food Animal Section, Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio
VETERINARY CLINICS OF NORTH AMERICA: FOOD ANIMAL PRACTICE VOLUME 11 • NUMBER 1 • MARCH 1995
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The teat mucosa surrounds a teat cistern that, during lactation, is filled with milk. The teat cistern is continuous proximally with the gland cistern. A distinct annular ring demarcates the teat cistern from the gland cistern (Fig. 1). This annular ring is of significance because it usually contains a large vein that encircles the base of the teat. Located at the distal end of the teat and connecting the teat cistern to the outside is the streak canal (papillary duct). At the junction of the teat cistern and the streak canal is the rosette of Furstenberg. This rosette is created when the mucosa of the teat cistern meets the stratified squamous epithelium of the streak canal. The circular teat sphincter muscle lies directly beneath the rosette of Furstenberg at the proximal end of the streak canal. The streak canal varies from 0.5 to 1 cm in length, and ends externally at the teat orifice. RESTRAINT AND ANESTHESIA
Over the years, many teat surgeries either have not been completed or have been completed in a less than satisfactory manner due to inadequate restraint and anesthesia. Successful outcome depends on meticulous suturing under aseptic conditions. IS Adequate restraint, tran-
Figure 1. The teat cistern, which is separated from the gland cistern by the annular ring, is shown. Note the large vein at the annular ring.
Figure 2. "Web" teat. Note the small bulge on the side of the primary teat. This bulge surrounds the teat sphincter of the web teat.
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quilization (if indicated), and anesthesia are necessary to perform teat and udder surgery in a manner that leads to a successful outcome. For simple procedures such as relieving a "hard milker," tailing the cow up (tail jack or tail hold) may be all that is required. This often can be combined with infusion of a small amount (3-5 mL) of local anesthetic agent into the teat cistern through the streak canal. This infusion anesthetizes the mucosa and submucosa, but is not adequate for repair of a teat laceration. For more complicated procedures, the cow should be restrained in lateral or dorsal recumbency. Although a surgery table provides ideal restraint for teat and udder surgery, one often is not available in a practice situation. General anesthesia occasionally is indicated, but most teat surgery can be performed under heavy tranquilization and a local block. Today, the tranquilizer of choice would seem to be xylazine (0.05-0.1 mg/lb) given intravenously. It should be noted that the use of xylazine in cattle has not been approved by the Food and Drug Administration. Xylazine often causes cattle to become recumbent and the practitioner should be prepared for recumbency if it is to be given. Once down, the animal can be furthe~ restrained with ropes, if indicated. Xylazine alone is not sufficient for teat surgery and a local block with lidocaine or xylocaine generally is used. An intravenous block has been described for anesthesia of the teat but it has not been widely accepted. I8 The local block usually is a ring block placed at the junction of the teat and udder. A volume of 10 mL usually is sufficient and a fine-gauge (23-25) needle is used. This ring block is simple to perform, does not interfere with healing because it is a regional block, and generally is sufficient for most teat procedures. For udder amputation, either general anesthesia or a large (50-100 mL) epidural can be used. 21 This large-volume epidural is necessary both to maintain recumbency and to provide anesthesia to the entire udder.
SUPERNUMERARY TEATS
Supernumerary teats are the most common congenital anomaly in cattle. 4 Supernumerary teats should be removed for cosmetic purposes and to prevent mastitis. This surgery ideally should be performed at 4 to 6 months of age. At this age, the animal is old enough for the practitioner to distinguish which teats are the primary teats and which, indeed, are supernumerary, yet the teats are small enough that bleeding is minimal and the site heals without complication. At this age, supernumerary teats can be removed with a serrated scissors. Teats always should be removed so the resultant cut is craniocaudal in orientation so the resultant scar blends with the normal folds of the udder. If supernumerary teats are large or if they are not removed until an older age, they will need to be damped with an emasculatome at the base of the teat prior to removal. If supernumerary teats are not removed before the animal is
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"springing," they should be dissected surgically or left until the animal is dry because udder edema may interfere with healing. To remove supernumerary teats in the "springer" or during lactation, the animal should be tranquilized and a local block placed. The teat then should be dissected surgically with an elliptical incision (craniocaudal orientation). This dissection should provide visualization of the mucosa of the accessory gland from which the supernumerary teat arose. This mucosa should be closed with a simple continuous suture of fine absorbable suture. The connective tissue should be closed in a similar manner. Last, the skin should be closed with interrupted sutures of nonabsorbable material.
"WEB" TEATS (CONJOINED TEATS)
A supernumerary teat occasionally is attached to the side of a primary teat. When this is the case, it may be visible as a bulge or bump on the side of the primary teat or merely as an extra teat orifice on the side of the teat (Fig. 2). In this case one, first must evaluate the situation carefully to be sure it, indeed, is a supernumerary teat with a separate gland and not a teat fistula connected to the primary teat cistern. This evaluation can be performed best by injecting dye into the orifice of the suspected supernumerary teat and milking the primary teat to check for the presence of dye. The dye normally used is 30 mL of new methylene blue (Fisher Scientific, Fairlawn, NJ). Treatment of a fistula into the teat cistern of the primary teat is the same as that discussed in the section on repair of teat fistula following teat laceration. The amount of secretory tissue in the accessory teat normally is of little or no consequence. If in doubt, one can milk or drain the accessory teat to determine its volume, or ascertain volume with the aid of contrast radiology or ultrasonography. Contrast radiography can be performed by injecting 10 mL of contrast material into the fistula and taking a radiograph of the affected teat and quarter. s, 7 Ultrasonography (if available) probably is the method of choice for evaluation of the udder.6 Surgery is indicated for accessory teats attached to the side of normal teats because incomplete milking of the accessory gland and trauma to its orifice often lead to mastitis, which is difficult to treat and may spread to the primary gland. Surgery usually is accomplished by an elliptical dissection around the mass of the supernumerary teat or, in the absence of a teat, dissection around the orifice (of the accessory gland). This elliptical incision must be parallel to the long axis of the primary teat. Dissection is carried deeper and the teat cistern of the accessory teat carefully is dissected free. This dissection can be aided by a side opening teat cannula inserted into the accessory teat orifice. Care should be used in this dissection to avoid opening the teat cistern of the primary teat~ Once the teat cistern has been isolated, it is removed at its junction with its gland cistern
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(gland cistern of the accessory teat). The wound then is closed in three layers, as described for removal of supernumerary teats in springing heifers or lactating animals. If one finds significant milk in the glandular tissue of the accessory teat, a procedure has been described for connecting the teat cistern of the accessory teat to the gland cistern of the primary teat. 16, 17 Once the teat cistern of the accessory teat has been exposed, as previously described, a side opening teat cannula is inserted into the primary teat and the tissue between the primary teat cistern and the accessory teat cistern is incised for a distance of 2 to 3 cm without entering the annular ring (large vein and excessive bleeding) between the teat cistern and gland cistern. The mucosa of the primary teat and accessory teat are opposed with a simple continuous suture of .4-0 polydioxanone (PDS, Ethic on, Somerville, NJ). Although this step may seem unnecessary, unsutured mucosal wounds of the teat have a strong tendency for excessive granulation tissue. This granulation tissue becomes so excessive it occludes the opening between the two teat cisterns if suturing is not performed. The incision into the teat then is closed in three layers, as described for teat lacerations.
CONGENITAL ATRESIA ("BLIND QUARTER")
Atresia usually is not observed until the onset of lactation. It often is considered to be congenital but it may be caused by trauma before the first lactation. Both trauma from being sucked and infection spread by flies have been mentioned as causes of "blind quarters." The indication of atresia is the heifer that freshens with minimal or no milk from one or more quarters. Atresia can occur in four 10cations-(1) the distal end of the teat (no teat orifice), (2) the teat cistern, (3) at the annular ring (junction of the teat cistern and gland cistern), and (4) fibrosis within the gland cistern. Careful evaluation is essential to determine the cause and extent of the problem. Physical examination, especially careful palpation, often reveals the cause of the problem. If not, contrast radiology or ultrasonography are very useful diagnostic tools. Heifers presenting with atresia should be evaluated with ultrasonography or radiography (contrast or double contrast). Contrast radiography is performed by injecting 10 mL of an iodine-based radiopaque material through the streak canal and into the teat and gland cisterns after aseptic preparation of the teat end. 5, 7 A film then is taken and compared with normal radiographic anatomy. Ultrasonography, if available, probably is more useful in evaluating normal interior teat structure. 6 Again, one must be familiar with the normal in order to interpret the abnormal. We use ultrasonography almost exclusively as the diagnostic tool to evaluate quarters that will not milk, not only in first-calf heifers, but also with "teat spiders"
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to evaluate the extent of the spider and amount of teat cistern wall involved. It should be noted that an obstructive lesion may be present for 6 days with very little, if any, decrease in milk flow for the lactation. After 6 days of obstruction, the gland begins to involute and production from the quarter in question will be decreased for the lactation in question. It should return to normal in subsequent lactations, however, if there is no scar tissue within the gland cistern.
OBSTRUCTION AT THE DISTAL END OF THE TEAT
Obstruction (atresia) at the distal end of the teat often is just imperforate skin. In this case, one often can squeeze the teat and observe a bulge over the area of the teat orifice. This bulge can be opened with a large (12-14) gauge needle or #11 scalpel blade. The end of the teat usually needs to be rolled between the thumb and finger before milking for several days. This serves to break down any small fibrinous adhesions that may be forming and helps keep the teat orifice patent until healing is complete. This surgery usually is very successful.
CONGENITAL OBSTRUCTION OF THE TEAT CISTERN If the teat cistern is obstructed by scar tissue, the amount and location of the scar tissue must be evaluated. In this case, sonography is far more helpful than contrast radiography because the contrast material used in radiography cannot penetrate the scar tissue and the extent of the scar tissue cannot be evaluated fully. If the teat is obstructed by a small bridge of scar tissue, it may be opened or removed through the teat orifice. If the obstruction is more than just a membrane, however, the results obtained through the teat orifice often are disappointing. When opened through the distal orifice and streak canal, a good milk flow is obtained initially, but decreases and eventually ceases over a period of several days. New obstruction may be caused by incomplete removal of the offending scar tissue but usually is due to the formation of excessive granulation tissue. The teat cistern is very prone to granulation tissue formation because the mucosa is very loosely attached and the blood supply is rich. If tissue removal is anticipated, it is advisable to perform a thelotomy. Over the years, there has been a great reluctance on the part of veterinary practitioners to open teats for fear of poor results (dehiscence). This fear is acquired through experience with teat lacerations that do not heal. There is a big difference in healing between a fresh teat incision and an old, contaminated laceration. The use of a thelotomy should not be feared. 2 A thelotomy should be performed parallel to the long axis of the teat and care should be taken to avoid the streak canal and distal 1 cm
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of the teat cistern as well as the annular ring at the base of the teat. Inserting a side-opening teat cannula into the teat cistern, if possible, often is helpful when opening the teat. Once the teat has been opened, the obstruction can be visualized and carefully dissected free. After removing the obstruction, the mucosa must be sutured carefully with 4-0 polydioxanone or polyglactin 910 (Vicryl, Ethicon, Somerville, NJ). If necessary, adjacent mucosa may be undermined and slid to provide closure with minimal tension on the mucosa. 7 If the defect created in removing the scar tissue mass is too large to close with minimal tension on the mucosa, the use of an implant should be considered if indicated economically. Because the use of an implant is not always successful, this possibility should be discussed with the owner prior to surgery and the prosthesis should be available in case it is needed.
TEAT PROSTHESIS
When the teat mucosa cannot be closed completely, it is advisable to place a teat implant. The teat implant consists of a piece of medical grade silastic tubing placed within the teat cistern. This tubing must be long enough to extend up into the gland cistern and the distal end of it must be rounded to minimize trauma to the rosette of Furstenberg and the teat sphincter. This piece of tubing gives the teat mucosa a template to form around, at the same time inhibiting formulation of granulation tissue by pressure. While the teat is open, the silastic tubing is sutured into place with nonabsorbable suture material in the mid teat cistern region. Three sutures usually are placed-one directly opposite the incision and two at 90 degrees from the original suture. These stay sutures should be placed so as to incorporate as much tissue as possible (without penetrating the skin). One of the main complications of teat implants is that they later dislodge and float free. Incorporating large amounts of tissue helps prevent this complication. This method leaves the area of the primary incision free of stay sutures and facilitates incision closure. The length of the silastic tubing to be used is debatable. A long tube that extends well into the gland cistern is less likely to float free over time, but it is more prone to "fracture" over time. At present, it seems advisable to use as long a tube as possible. It also is debatable whether the tube needs to be removed if and when it floats free. My personal preference at this time is to leave it alone unless it causes problems. The portion of the tube that will be within the gland cistern should be fenestrated to allow milk to enter the tube in more than one place. Care should be taken in making these fenestrations to avoid weakening the tube any more than necessary. Once the implant has been placed, the teat is closed in a routine manner, as described in the section on teat laceration. It should be noted that teat implants are only about 50% successful,
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whether used for teat spiders or for scar tissue in first-calf heifers. The failures occur after the implants float free or are removed; at that time, some teats again close with scar tissue. Any evidence of mastitis precludes the use of a teat implant. If one is suspicious that infection may be present or if the owner has attempted milking the cow with a teat cannula, the milk should be cultured before surgery or, if this is impossible, during surgery. Because the teat implant is a foreign body, any mastitis can lead to a disastrous result. OBSTRUCTION AT THE ANNULAR RING If an obstruction at the annular ring is a thin membrane, it can be incised through the streak canal using a sharp, pointed teat bistoury.8 The bistoury is inserted to the membranous obstruction and a large X is made in the membrane. Care is taken to avoid the vascular ring located within the annular ring. If the vascular ring is cut, it often is necessary to open the teat to control the resultant hemorrhage. In the case of a thin membrane, the flaps created by the X-shaped incision fall into the teat cistern and milk flow is obtained. Experience, however, indicates that the obstruction usually is not membranous, but rather a thick piece of tissue. In this case, a thelotomy must be performed and an implant placed if one is to hope for any chance of success. As previously mentioned, if this is the case, the milk must be evaluated for evidence of mastitis and the prognosis must be discussed with the owner.
FIBROSIS WITHIN THE GLAND CISTERN
Although fibrosis within the gland cistern can be suspected by palpation, it can be confirmed only by contrast radiography or, preferably, ultrasonographic evaluation. If fibrosis is detected within the gland cistern during the evaluation, the prognosis for surgical success is hopeless. If milk is not being produced or collected into a gland cistern, no surgical procedure exists at this time that will correct the problem. One should be aware that any congenital obstruction may be accompanied by fibrosis of the gland cistern, so careful evaluation of the entire quarter is necessary before performing any surgery. It is embarrassing to perform a nice piece of surgery to correct an obstruction within the teat cistern only to find out that the quarter does not milk. HARD MILKER (TIGHT TEAT SPHINCTER)
A hard milker usually is caused by trauma to the teat end. This trauma usually is in the form of a crushing injury and often is self inflicted; the cow crushes her own teat between her leg and the floor
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when trying to rise. Other causes for this trauma are poor milking machine function, delivering excess vacuum to the teat end, and frostbite of the teat end. Any traumatic insult to the area of the teat sphincter causes an increase of scar tissue, which leads to a small stream of milk and slow milking. As such, this type of injury often is self perpetuating. Obstructive lesions at the teat sphincter also can occur because of flaps in the area of the rosette of Furstenberg. The typical history is that one quarter takes a lot longer to milk out than the other three quarters. As already mentioned, this longer milking effort increases the trauma to the end of the teat and, in time, may increase the amount of scar tissue and make the cow even more difficult to milk. The trauma to the teat end, coupled with incomplete milking, often leads to mastitis. The traditional owner treatment for the hard milker is the use of a teat dilator, which over stretches the teat sphincter. Teat dilators may be successful, but more often fail or predispose to mastitis. Some types of teat dilators also are brittle and can break off, leading to intramammary foreign bodies which then must be removed. In order to be effective, a teat dilator must be used over a period of several days. Surgical intervention probably is more successful than dilators. There are many surgical instruments in the market specifically designed for the relief of a hard milker. All of these instruments either cut or stretch the teat sphincter. Before considering surgery on the teat sphincter, it is important to realize that the keratin lining of the streak canal is very important in preventing mastitis. Any disruption of this keratin lining (especially a disruption from the top to the bottom of the streak canal) will increase the chance of mastitis until a new keratin layer has been secreted. With this in mind, it probably is not wise to use any instrument that removes the keratin lining or damages it from the top to the bottom. Surgery for a stenotic teat sphincter should be performed before the morning milking so surgical response can be monitored and proper aftercare can be initiated. After surgical preparation of the teat, a teat knife is inserted through the streak canal, using care to avoid cutting the entire length of the streak canal. The knife is angled at 45 degrees and a cut is made at the rosette of Furstenberg (area of the sphincter muscle), and the knife is gently removed from the teat (Fig. 3). The teat is milked forcefully to assess progress. If necessary, the teat sphincter is cut again at 180 degrees from the first cut. Cuts can be repeated at 90 degrees if necessary. Milk flow should be evaluated after each cut. Evidence that the correct amount of cut has been made is provided when the teat drips a fine stream of milk for 1 or 2 minutes after a forceful stream of milk is expelled from the teat. After surgery, the quarter should have several streams of milk expressed every 15 minutes for the next 2 or 3 hours and then once every hour until the next milking. This stripping must be forceful; the goal is to prevent closure of the incisions. It may be necessary to roll the end of the teat between the thumb and finger to break down any fibrinous adhesions starting to form between the cut edges. If the oper-
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Figure 3. The use of the Lichty Teat Knife to open a "hard" milker is demonstrated. The knife is angled so that it cuts the sphincter muscle without cutting the entire length of the streak canal.
Figure 4. Teat "spider." Initially, the hematoma and later the scar tissue bulge into the teat cistern.
ated teat cannot be milked frequently, a dilator may be placed in the streak canal for a day or two. The results obtained with dilators are less satisfactory than frequent stripping. ENLARGED TEAT ORIFICE (DRIPPING MILK)
If one is overzealous in treating the "hard milker" a leaker may develop. Enlarged teat orifices are very difficult to treat. Using a TB syringe and a fine (27 gauge) needle, one can inject a drop of Lugol's iodine at four places (every 90 degrees) around the teat sphincter to create scar tissue in the hope of tightening the teat sphincter, but this often is unrewarding. s TEAT LACERATIONS
The prognosis in teat lacerations depends on several factors and can vary from good to hopeless. Needless to say, full-thickness lacerations (into the teat cistern) have a much poorer prognosis than partial-thick-
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ness lacerations. The fresher a laceration is when repaired, the better it heals. Prognosis drops in lacerations that are more than 4 hours old and, after about 12 hours, the prognosis is extremely poor. Because of the longitudinal blood supply of the teat, vertical lacerations heal far better than horizontal lacerations. Again, because of blood supply, lacerations that are near the base of the teat (its attachment to the udder), heal better than lacerations of the distal teat. Lacerations that involve the teat sphincter and streak canal have a much poorer prognosis than those that do not involve these structures because it is difficult to effect anatomic repair. Before attempting repair, one must clean and thoroughly evaluate the laceration for any small, deep holes that may be covered by a fibrin clot. Even small fistulas change the method of repair and the prognosis. If one is to attempt repair of a laceration of unknown duration or known to be over 4 hours old, extensive debridement is necessary. Any tissue that is infected, necrotic, or devitalized must be removed completely. There is, however, very little "extra" tissue available in the teats of today's dairy cow, so delicate dissection is necessary to remove desiccated tissue but to preserve all the normal tissue possible. Debridement should continue until fresh, bleeding tissue is obtained. Once anesthesia and debridement have been accomplished, suturing with fine (4-0 or smaller) absorbable suture increases the chance of success. If full-thickness lacerations are left to granulate rather than sutured, 60% to 75% will heal by second intention, with fistula formation.lO, 14 In the past few years, thoughts on the suture pattern for teat lacerations seem to have changed greatly. It seems that the mucosa should be sutured with a simple continuous pattern using fine (4-0 or 5-0) absorbable suture material with a swedged atraumatic needle. 12 The mucosa must be sutured carefully to obtain a milk-tight seaL After completely closing the mucosa, it is helpful to insert a teat cannula through the teat sphincter and gently "probe" the suture line to check for holes or weak areas. If the mucosa is not sutured, granulation tissue proliferates into the lumen of the teat cistern and later obstructs milk flow. 19 When biting full thickness in the mucosa, one is more certain to completely seal the mucosa and prevent milk fistulas. Because the mucosa is very thin and delicate, it should be supported by another simple continuous layer of fine absorbable suture placed in the submucosa. The remainder of the teat wall then should be closed with vertical mattress sutures of a noncapillary materiaL Vetafil (Bengen Company, Hanover, Germany) or Braunamid (B. Braun, Melsungen, Germany) are ideal sutures for this. The deep bite of the vertical mattress is placed adjacent to the submucosal suture line to give it support, whereas the shallow bite is very superficiaL Using this suture technique, we have successfully put cows back on machine milking at the next scheduled milking.12 Previously, Larson's teat cannulas have been used to achieve milk out. It now is recognized that the use of cannulas to drain the quarter is contraindicated because it increases the risk of mastitis and may damage the repair? Another approach used in the past was to not milk for 4 or
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5 days. Although this was not detrimental to production, it did greatly increase the tension on the suture line. It recently has been advocated that tissue adhesives be used to repair teat lacerations. 10, 14, 19 From the research that has been done, it appears that tissue adhesives give very satisfactory healing results. Research also has shown that tissue adhesives cause a rather severe tissue reaction, characterized by a marked foreign body reaction.lO In addition, it has been shown that, if tissue adhesives are to be used, they should be used independently and not in combination with suture material. 14 In the normal course of events, the tissue adhesive is extruded as healing takes place. Suturing in conjunction with tissue adhesives prevents this extrusion and increases the foreign body reaction.
Special Care Teat Lacerations If a non-full-thickness horizontal laceration results in a ventrally based skin flap, the blood supply should be evaluated carefully. If the blood supply is inadequate, the flap should be trimmed to healthy tissue. The remaining wound may be closed in some cases or left to granulate if the remaining tissue is inadequate for closure. A teat occasionally is stepped on in such a manner that the teat sphincter is totally separated from the surrounding skin. Upon examination of this wound, it appears that there is no teat sphincter and the end of the teat is raw. Closer examination reveals that, in reality, a large hematoma is held in place by a flap of skin and the teat sphincter and streak canal are recessed above this hematoma. This type of laceration is painful, difficult to manage, and often leads to mastitis. Although it seems radical, the best way to handle these lacerations is to remove all of the undermined skin with a pair of sharp scissors.13 When removing the skin, one should exercise caution to avoid the teat sphincter and streak canal. Although this leaves a raw teat end, the resultant lesion is much less painful than the undermined skin and hematoma. In addition, this procedure greatly reduces the risk of mastitis. The resultant wound is treated as an open wound and allowed to heal by second intention.
Teat Laceration Aftercare
Any full-thickness teat laceration or one that damages the teat end should be treated as if it were a case of mastitis. Culture and sensitivities probably are indicated and, certainly, appropriate antibiotics should be employed, both intramammary and systemically. Care should be taken with intramammary infusion to avoid damage to the repair. Because the teat has an excellent blood supply, skin sutures can be removed in 10 days.
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TEAT FISTULA
Although teat fistulas may be congenital, they usually follow the unsuccessful repair of a teat laceration or are the end result of a laceration in which no repair was attempted. When attempted repair fails, the laceration should be allowed to granulate until the swelling and infection subside. This usually takes 2 to 4 weeks. While waiting, the wound should be cleaned daily and mastitis prevention should be instituted. Once the wound has granulated to an end-stage fistula, surgery should be performed to correct the fistula. After preparation and a ring block, the entire fistulous tract is dissected out. The fistula is dissected out with an elliptical incision around the fistula that is parallel to the long axis of the teat. This dissection must be carried down all the way into the teat cistern, exposing healthy teat mucosa. Once the dissection has been completed, the resultant hole is closed as described for teat lacerations (three-layer closure). TEAT SPIDER
A teat spider can be defined as a mass of scar tissue protruding from the mucosal surface of the teat and into the teat cistern (Fig. 4). It usually is caused by an injury and initially is a large hematoma that causes the loosely attached mucosa to bulge into the teat cistern. This hematoma later organizes into scar tissue and the mass of scar tissue impedes milk flow through the affected teat. Teat spiders traditionally have been extracted through the streak canal. Certainly, for pedunculated masses or free floating masses of scar tissue, this probably is still the method of choice. In working with mural plaques of scar tissue, however, the end result after using a Hugg's tumor extractor (Jorgensen Laboratories, Loveland, CO) or a Cornell teat curette (Jorgensen Laboratories, Loveland, CO) often is worse than the initial obstruction. 2o With pedunculated teat spiders, one can palpate the mass within the teat cistern and, by working through the streak canal with an alligator forceps, the mass can be grasped, broken loose from its stalk, and extracted through the streak canal (while squeezing the teat above to help force the fibrotic mass out with hydrostatic pressure at the same time). If the pedicle already has broken and the mass of scar tissue is floating free within the lumen of the teat cistern, it can be removed in a similar fashion. When the teat spider is a mural-like plaque, the traditional method has been to remove it through the streak canal with various curettes or tumor extractors. The teat mucosa is very loosely attached and has a rich blood supply. These two factors make it especially prone to the formation of granulation tissue. Although removal of a plaque of scar tissue through the streak canal often is successful initially, in many cases it later (2-3 days) obstructs with granulation tissue and milk flow ceases again. It therefore probably is preferable to open the teat (vertically) on
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the side opposite the scar tissue mass. The mass of scar tissue then can be gently dissected free and the mucosa over the defect closed with a simple continuous layer of fine absorbable suture material. 1 If the mucosa is difficult to close, it can be undermined before closure, as mentioned in the section on scar tissue obstruction. Also, as with congenital obstructions, if the mucosa cannot be closed, the use of an implant should be considered. This approach (thelotomy) allows for careful inspection of the teat, meticulous dissection, and hemostasis. After closing the defect, the primary incision is closed in three layers in the same manner as for any other teat laceration. There seems to be a lot of reluctance to approach teat spiders in this manner, for fear of primary wound dehiscence. The reference point for most bovine practitioners is the fact that many teat lacerations do not heal well, but fresh, noncontaminated vertical teat incisions heal very well. TEAT AMPUTATION
Teat amputation usually is performed in cases of irreversible damage to the teat, which may be caused by gangrenous mastitis or severe trauma. In cases of gangrenous mastitis, the teat may be amputated without use of an anesthetic agent. In the case of severe trauma, the teat must be blocked (ring block) before amputation. An emasculatome should be placed across the teat at the junction of the proximal and middle thirds. This avoids the vascular ring at the annular ring and provides good hemostasis to the distal teat. The teat then is dissected sharply distal to the emasculatome. Some recommend opening the teat cistern to provide better drainage of the gland cistern. If this is the case, it is advisable to suture the mucosa to the skin with overlapping horizontal mattress sutures to help ensure hemostasis. Although the quarter will continue to secrete milk for a period of time (except in cases of gangrenous mastitis), it will dry up due to secondary infection and mastitis. Some prefer to try to dry the quarter off before teat amputation, but that usually is difficult because the damage to the teat is too severe to retain the sclerosing agents within the udder. UDDER AMPUTATION
Udder amputation is indicated in individuals of extremely valuable genetic potential with chronic mastitis that is debilitating enough to render them unsuitable for embryo transfer. Although udder amputation has been suggested as a treatment for toxic mastitis, that is not a good application for this procedure. Udder amputation should be performed after mastitis has been treated and the udder is in a state of remission, if at all possible. Experience has shown that removal of actively infected udders results in a much lower success rate, so vigorous medical therapy should be undertaken before surgical intervention in any potential case of udder amputation.
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After the decision has been made to amputate the udder and the animal is a good surgical candidate, one must decide on an anesthetic regime. Although amputation of udders has been described using a large volume epidural (50-100 mL),3 it probably is preferable to amputate udders under general anesthesia, if at all possible. It also is recommended that a blood donor be available or even that blood be drawn and banked for a transfusion in case it is needed. This recommendation probably is more applicable to the bovine than to the ovine or caprine. If possible, the animal should be positioned in dorsal recumbency. This facilitates working on both sides of the udder. If dorsal recumbency is not possible, the animal will need to be rolled from one side to the other during surgery and the appropriate preparations should be made. The external pudendal artery should be ligated before any of the venous system is ligated. This gives the blood in the udder some chance to drain back into the circulation before the udder is removed. A skin incision is made parallel to the base of the udder and about 3 to 5 cm ventral to the dorsal edge of the mammary tissue. This incision eventually extends completely around the udder in an elliptical manner. Hemorrhage should be controlled by cautery or ligation. -Once through the skin, the incision is carefully extended through the lateral suspensory ligament of the udder. Care should be taken because the external pudendal artery and vein lie directly beneath the lateral suspensory. The external pudendal artery and vein can be found coursing from the inguinal ring in a tortuous manner to the juncture of the front and rear quarters of the udder, where both the artery and vein bifurcate. They should be ligated as they exit the inguinal ring and before they bifurcate. It has been recommended that the artery and vein be separated from each other and ligated separately. If this is attempted, extreme care must be taken during this procedure. In practice, the artery and vein often are ligated together. This certainly leaves the possibility of an arteriovenous shunt, but in reality, that rarely occurs. Once the artery and vein have been ligated on one side, the procedure should be repeated on the opposite side unless a hemimastectomy is being performed. At this point, the incisions (each side) are extended anteriorly and the subcutaneous abdominal veins are ligated. It should be noted that although textbooks and articles report that there is one subcutaneous abdominal vein for each half of the udder, in reality, these veins have multiple branches as they approach the udder.l1 Each branch must be double ligated individually. Once the subcutaneous abdominal veins have been ligated, the skin incisions are extended posteriorly and the perineal veins are ligated. There should be one perineal vein on each side, although this is somewhat variable. After ligating all the major vessels, the median suspensory ligament is cut near the body wall. Ideally, about 1 to 2 cm of medial suspensory should remain on the body to give a place to anchor the skin and help obliterate dead space during closure. If only a hemimastectomy is being performed, the right and left half of the median suspensory ligament
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can be separated and only the half of the median suspensory involved with the amputated half is severed. Once the udder has been amputated, the skin is closed. In performing the skin closure, the dead space is obliterated, if possible. This usually includes taking bites of the median suspensory ligament as the skin is closed. Postoperatively, we should hope for first-intention healing, although second intention seems to be more common. Although umbilical tape has been recommended in the literature as the ligature of choice, postoperative infection is much less of a problem if absorbable ligatures are used. If absorbable sutures are used, one should be aware of the large vessels that are being ligated and appropriately sized suture should be used.
References 1. Aher VD, Bhokre AP, Usturge SM: Open teat surgery in bovine and caprine. Indian Vet J 67:469-471 2. Arighi M, Ducharme NG, Horney FD, et al: Invasive teat surgery in dairy cattle, II. Long-term follow-up and complications. Can Vet J 28:763-767, 1987 3. Brewer RL: Mammary vessel ligation for gangrenous mastitis. J Am Vet Med Assoc 143:44-45, 1963 4. Bristol DG: Teat and udder surgery in dairy cattle-Part I. Compendium 11:868-873, 1989 5. Bristol DG: Teat and udder surgery in dairy cattle-Part II. Compendium 11:983-988, 1989 6. Cartee RE, Ibrahim AK, McLeary D: B-Mode ultrasonography of the bovine udder and teat. J Am Vet Med Assoc 188:1284-1287, 1986 7. Ducharme NG, Arighi M, Homey FD, et al: Invasive teat surgery in dairy cattle, I. Surgical procedures, and classification of lesions. Can Vet J 28:757-762, 1987 8. Fox FH: Teat surgery. Iowa State University, Iowa Veterinarian, November-December, 1966, pp. 22-24 9. Gaymer J: The use of tissue adhesives in teat surgery. In Proceedings of the 16th Bovine Practitioner, Stillwater, OK, 1984, pp 175-176 10. Gaymer J, Watson WL, Coy CH, et al: Healing of experimentally induced wounds of mammary papilla (teat) of the cow: Comparison of closure with tissue adhesive versus nonsutured sounds. Am J Vet Res 45:1979-1983, 1984 11. Guard WF: Surgical Principles and Techniques. Columbus, OH, WF Guard, 1953 12. Hull BL: Teat and udder surgery. In Proceedings of the Annual Veterinary Surgery Forum, Chicago, IL, 1985, pp 67-71 13. Lloyd K: Teat end injuries-A surgical procedure. Agri Practice, 1994 14. Makady FM, Whitmore HL, Nelson DR, et al: Effect of tissue adhesives and suture patterns on experimentally induced teat lacerations in lactating dairy cattle. J Am Vet Med Assoc 198:1932-1934, 1991 15. Modransky P, Welker B: Management of teat lacerations and fistula. Vet Med 88:9951000, 1993 16. Rijkenhuizen ABM, Hemeth F: Een chirurgische behandeling voor twee met elkar vergroeide spenen. Tijdschr Diergeneeskd 109:389-393, 1984 17. Shappell KK, Schneider T: Surgical treatment of accessory teat and gland complexes in three cows. J Am Vet Med Assoc 195:623-626, 1989 18. Surborg VH: Regionale Intravenose Anasthesie in der Zitzenchirugie des Rindes. Dtsch Tierarztl Wschr 87:333-335, 1980 19. Tulleners E, Hamir A: Effects of teat cistern mural biopsy and teatoscopy stab versus
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longitudinal incision with or without tube implant on incisional healing in lactating dairy cattle. Am J Vet Res 51:1257-1266, 1990 20. Weaver AD: Teat surgery in cattle. Veterinary Annual 107-112, 1982 21. Wright JG, Hall LW: Veterinary Anaesthesia and Analgesia, ed 5. Baltimore, Williams and Wilkins, 1961
Address reprint requests to Bruce L. Hull, DVM, MS Department of Veterinary Clinical Sciences The Ohio State University College of Veterinary Medicine 601 Vernon L. Tharp Street Columbus, OH 43210-1089