Urologic Disorders of the Geriatric Dog

Geriatrics and Gerontology

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Urologic Disorders of the Geriatric Dog

Donald R. Krawiec, DVM, MS, PhD*

It is often said that old age is not a disease. It is, however, taken for granted that as animals get older their organ system functional ability will tend to deteriorate. This is certainly true of the urinary system. Renal failure has been reported to be the second leading cause of nonaccidental death in dogs, and the reported average age of onset of renal failure in dogs is 6. 95 years. 8• 25 Other urinary problems that are primarily seen in middle-aged or geriatric dogs are urinary incontinence, prostatic disease, and bladder tumors. Diagnosis of disease in older animals can be a real challenge because the manifestations of disease may differ between young and geriatric patients. Signs of disease are often more insidious, nonspecific, and atypical in older animals. 35 The first sign of renal failure in older animals may, for instance, be nocturia or urinary incontinence rather than polyuria. Polyuria of course will occur in any age animal with renal failure, but in older animals the increased urine output puts stress on a urethral sphincter that may be weakened or on a bladder that is no longer able to hold as much urine, both of which may be an age-related problem. Therefore, the polyuria may result in urinary incontinence and nocturia, which may be the first abnormality that the owner notices. Older animals are in general not as active as young ariimals, and owners are much more likely to pass off lethargy as an inevitable consequence of the aging process. As a result, if an animal has a disease process that results primarily in lethargy, owners are more likely to wait longer to seek veterinary attention after this problem is noticed. It also can be very difficult for a veterinarian to determine which identified problems in geriatric patients should be further evaluated. It would be rare not to find an abnormality on a clinical chemistry profile taken from a geriatric patient. Determining which of the abnormalities is actually affecting the animal's health and well-being and which, therefore, requires further examination *Associate Professor, Department of Veterinary Clinical Medicine, University of Illinois College of Veterinary Medicine, Urbana, Illinois Veterinary Clinics of North America: Small Animal Practice- Vol. 19, No. 1, January 1989

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is at best a very imprecise art. This is a major concern because of the fragile nature of geriatric animals and their inability to handle stressful situations. Hospitalizing a geriatric animal to pursue an inconsequential problem could severely affect the health of the patient. When evaluating geriatric animals, it is especially important to use all your diagnostic skills, including history taking, physical examination, and laboratory data interpretation, and common sense to determine the importance of an identified abnormality. RENAL FAILURE Kidneys of geriatric animals and humans are smaller in weight and size, have decreased glomerular numbers and decreased tubular size and weight, and have increased mesangium and fibrosis. 8· 36 This change in morphology is associated with decreases in renal blood flow, decreased glomerular filtration, decreased urinary concentration ability, and decreased ability to maintain sodium, water, and acid-base homeostasis. Decreased concentrations of renin, aldosterone, and activated vitamin D have also been found. 36 Decreasing renal function over time is likely due to a number of causes. One possible cause of decreased renal function over time is the regular consumption of high protein diets. One identifiable clinical sign of renal aging in rats is proteinuria. Proteinuria is associated with significant renal structural abnormalities.36 High protein meals cause a degree of glomerular hyperfiltration, which can damage the glomerular vascular endothelium. This damage will result in protein leakage into the glomerular space and proteinuria. 4 Protein in the glomerular space is irritating and will cause inflammation and sclerosis. The destruction of the glomerulus will eventually result in the destruction of its attached tubule. It has recently been shown that healthy people who eat meat as a part of their diet have significantly higher proteinuria and mean diastolic bloodpressures than do human vegetarians. 38 · · Fortunately, the kidney has a great reserve of nephrons. It is unlikely, therefore, that the slow deterioration of renal function over time, whether due to dietary protein or other causes, will by itself result in renal failure. However, geriatric animals will be less able to tolerate other types of renal insult because they have less renal reserve on account of this deterioration. It is therefore of upmost importance to identify and eliminate any potential reversible cause of renal disease in elderly animals as quickly as possible. Renal ischemia due to heart. failure, for instance, can result in ischemic renal disease and failure if not identified and treated. Hypercalcemia diabetes mellitus, urinary tract infection, and urinary obstructions are all potentially reversible diseases that may have serious impact on the kidneys if not identified and treated appropriately. These conditions pose an even greater threat to geriatric animals with reduced renal reserve. Veterinarians should also use caution when using nephrotoxic drugs in a geriatric animal. Because the geriatric kidney is much more fragile, it may be severely damaged even when using routinely recommended dosages.

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Because renal failure is primarily a disease of older animals, standard recommendations for the conservative treatment of renal failure were formulated with this in mind and can usually be followed when treating the geriatric animal. 33 Recommendations that are aimed at decreasing the progressive nature of chronic renal failure are to decrease dietary protein intake, to control hypertension, and to maintain normal serum phosphorus levels. Commercial diets that are available for feeding dogs and cats with renal failure should, therefore, have reduced protein, salt, and phosphorus (Prescription Diets kid, u/d, Hill's Pet Products, Topeka, KS) . Unfortunately, renal failure is a dynamic process that will occur in varying degrees of severity. It is, therefore, impossible to make recommendations concerning dietary protein intake that will cover every animal that you examine. In general, our therapeutic goal is to feed enough protein so that the patient does not start metabolizing endogenous proteins. It is recommended that dogs with serum creatinine levels less than 4.5 mg per dL be maintained on 2.0 to 2.2 g of high biologic quality dietary protein per kg per day. Dogs with serum creatinine levels greater than 4.5 mg per dL should be fed 1. 3 g of protein per kg per day. 33 Commercial dog foods that provide these levels of protein are available (Prescription Diets kid, u/ d). Animals on protein-restricted diets should have adequate amounts of dietary fat and carbohydrate to fulfill 100 per cent of their daily caloric needs. This will ensure that dietary protein is only used by the animals for anabolism and is not broken down for energy. Regardless of the amount of dietary protein restriction, the animal should be carefully monitored for excesses and deficiencies of dietary protein. Animals that are continuing to show signs of uremia that may be caused by catabolic products of dietary protein metabolism may have their protein further reduced. On the other hand, animals that are losing muscle mass as a result of decreased protein intake should have their protein intake increased. Hypertension is generally initially treated by restricting dietary salt intake. Recommendations for salt restriction based on experimental evidence using hypertensive dogs in renal failure are unfortunately not available. Currently available commercial diets that are formulated for animals in renal failure contain sodium at a level between 0.21 and 0.26 per cent of dry matter (Prescription Diets kid, u/d). Homemade diets that provide an animal with 35 mg sodium per kg per day would closely approximate the level found in commercial renal failure diets. 32 Other medications that have been advocated in the treatment of hype rtension in renal failure include diuretics, sympatholytic agents, and vasodilators. 7 Hyperphosphatemia is usually controlled by feeding low phosphorus diets. Most of the phosphorus in diets is found in the protein portion. Therefore, phosphorus is reduced in diets by decreasing the protein content. Renal failure diets that are low in protein will also be low in phosphorus. Oral phosphate binding agents, aluminum hydroxide and aluminum carbonate containing antacids at a dosage of 30 to 90 mg per kg per day, have been advocated as serum phosphorus reducing medications. 33 I only use these products as a last resort if protein restriction does not maintain normal serum phosphorus levels. Serum phosphorus levels should be maintained below 6 mg per dL, and fractional excretion of urinary

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phosphorus should be maintained below 30 per cent. 11 • 12 Hypophosphatemia should not be induced. Recommendations for treating animals with renal failure aimed at ameliorating the signs of uremia are to restrict dietary protein, to always make sure the patient has plenty of water, to avoid putting the animal in stressful situations, to administer water-soluble vitamins, to treat acidosis, to use anabolic steroids to treat the anemia associated with chronic renal failure, and to control hypocalcemia. Animals in renal failure cannot concentrate their urine and, therefore, cannot conserve water. Restricting water intake for even short periods of time could result in severe dehydration. Emotional stress will induce a catabolic state that will worsen the uremic state. Nonrenal diseases will induce a stress that can have devastating consequences on animals with renal failure. Disease states that induce mild anorexia and decreased water intake could result in severe uremic crisis _if they occur in animals in renal failure. Therefore, it is recommended that animals in renal failure be kept in as protected an environment as possible and that if the patients show any signs of illness their veterinarians should be contacted immediately. Oral supplementation of vitamins B and C is recommended because animals in renal failure cannot conserve water-soluble vitamins. 32 The acidosis of chronic renal failure is treated with oral sodium bicarbonate at a dose of 5 to 30 grains three times per day. Sodium bicarbonate therapy may be instituted if the urine pH is below 6.0 cir if plasma bicarbonate levels are below 18 mEq per L. 32 Urine pH should not be allowed to increase beyond 7.5, and plasma bicarbonate should not be allowed to increase beyond 26 mEq per L because this may mean alkalosis was induced. Ideally, hypocalcemia is treated by reducing serum phosphorus levels. In certain instances, however, oral calcium or vitamin D supplement must be used to maintain serum calcium levels. It is my experience that animals with renal .failure and clinically significa~t hypocalcemia have a very poor prognosis. Oral calcium can be given at i dqse of 100 mg per kg per day. The dosage of 1,25 vitamin Din humans has been reported to be 0. 25 J..Lg given daily or every other day. 32 A canine dosage is not available; therefore, the best dosage must be selected for each patient based on response to treatment.

URINARY INCONTINENCE The average age of dogs with acquired urinary incontinence (UI) is between 5.3 and 8.3 years. 10· 31 • 34 This would indicate that UI is primarily a disease of middle-aged or older animals. The most common causes of urinary incontinence in dogs are urethral incompetence, urinary tract infection, and polyuria/polydypsia. 23 Urethral incompetence is commonly referred to as hormone-responsive estrogendependent incontinence and is most often seen in spayed female dogs .23 It can, however, also be seen in intact females and in both neutered and intact males. Urinary tract infection usually causes urge incontinence and can be seen in both sexes. It appears, however, to be more common in

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females than in males. 29 Treating a urinary tract infection with an appropriate antibiotic will often eliminate the incontinence problem. Polyuria can be produced by a number of pathologic abnormalities and also by certain medications. 15• 16 It will place added stress on the urethral sphincter, which may result in incontinence. Eliminating or ameliorating the increased urine output may eliminate or substantially decrease the incontinence problem. Geriatric animals can also have either behavior problems or debilitating diseases that may be the cause of Ul. Older animals may become more dependent on their owners and may urinate when they get excited while greeting their owners. These dogs may have to be retrained to empty their bladders more frequently or to become less excited in stressful situations. Debilitated animals may have to be trained to use newspaper to urinate on or may require help to go outside to urinate. 24 Determination of the causes of UI requires careful evaluation of data obtained from the history, physical examination, and laboratory assays. The history should include information concerning previous illness or surgeries. It should also be determined if the patient is currently receiving any medications. The history should also include information on the circumstance of the incontinence. Urethral incompetence is most often seen while the animal is relaxing or asleep. A typical complaint for this problem is that the animal urinates in its bedding. An animal will almost never urinate in its bedding voluntarily. The physical examination should include a complete neurologic examination; abdominal palpation to evaluate the bladder for distention, tenderness, and irregularities; inspection and palpation of the external genitalia of both males and females; and a digital rectal examination of both males and females. The physical examination should also include an evaluation of urine stream and the patients behavior while urinating. Animals should also be interrupted while urinating to assess their ability to stop urinating midstream. This will help evaluate urethral tone. Residual urine volume should be de termined after they complete urination to determine if they have a problem completely emptying their bladder. Residual urine volumes should not be greater than 0. 2 to 0.4 ml per kg. 27 The minimum laboratory analysis of animals with UI should be a urinalysis. A urine culture should be performed if the urinalysis is consistent with a urinary tract infection. If evaluation of data from the history, physical examination, and urinalysis do not suggest a cause for the UI, further laboratory analysis may be required. Other laboratory assays that may be necessary include a complete blood count, serum chemistry analysis, abdominal radiographs, and ultrasound analysis. Some specialty clinics also have the ability to perform electromyography, cystometrography, and urethral pressure profiles. These assays may help localize the problem to the bladder or urethra. Ideally, therapy should be directed at the specific cause of the UI. Sometimes a specific cause cannot be ide ntified, and only nonspecific treatment of the sign of incontinence can be implemented. Medications that can increase or decrease bladder contraction or increase or decrease urethral contraction are available. 6• 23 • 24 In order to use these medications

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appropriately, it is imperative to localize the problem to the bladder or urethra and to determine if the problem is one of excessive contraction or relaxation. Cholinergic agents (bethanechol, 5 to 15 mg given orally 3 times a day) may be utilized to increase bladder tone. Anticholinergic agents (propantheline, 5 to 30 mg given orally three times a day) may be used to decrease the spastic contraction that might accompany urge incontinence. Phenoxybenzamine (2.5 to 30 mg to a maximum of 0.5 mg/kg given orally once a day), which is an a-adrenergic blocking agent, may be used to decrease urethral tone. Diethylstilbestrol (0.1 to 1 mg given orally once a day for 3 to 5 days, then no more than 1 mg per week) may be used in females, and testosterone cypionate (2.2 mg/kg given IM once every 30 days) may be used in males to increase urethral tone to treat cases of urethral incompetence. Also, a-adrenergic agents (ephedrine, 15 to 50 mg to a maximum or 4 mg/kg given orally three ~imes a day; phenylpropanolamine, 12.5 to 50 mg given orally three times a day) will directly stimulate urethral a-adrenergic receptors and therefore increase urethral tone. a-Adrenergic agents have been used successfully to treat urethral incompetence. BLADDER TUMORS Bladder tumors are the most common tumor of the urinary tract. 37 They occur primarily in older dogs, and the average age at diagnosis of dogs with this condition has been reported to be between 9.1 and 9.4 years. 5 · 30 Some reports indicate that bladde r neoplasia occurs more frequently in female dogs than in male dogs. 17 In humans, males are more prone to bladder tumors than are females. 37 Scottish Terrier, Shetland Sheepdog, Beagle, Collie, Cocker Spaniel, Springer Spaniel, Dachshund, Boxer, Labrador Retriever, West Highland White ' TEfrfier, and Cairn Terrier are the most common breeds diagnosed with bladder tumors.5 · 17· 30 There is evidence that industrial chemicals and normal urine substances may play a role in bladder carcinogenesis and tumor growth promotion. 37 Chronic irritation seems to be a predisposing factor for the development of bladder tumors along with urolithiasis, cyclophosphamide, beta naphthylamine, arylamines, benzidine, metabolites of tryptophan, virus bracken fern ingestion, and tobacco use. 14• 37 Dogs and humans seem to be similarly susceptible to bladder neoplasia, and there seems to be a positive correlation between numbers of bladder tumors in dogs and the overall industrial activity of the areas in which the dogs lived. Dogs, therefore , could be used as a sentinel for environmentally induced bladder cancer. 18 Bladder tumors occur more commonly in dogs than in cats. It. had been proposed that cats are either less susceptible to tryptophan metabolites or metabolize tryptophan differently than do dogs. Tryptophan metabolites are excreted in the urine and have been incriminated as a cause of transitional cell carcinoma in the dog. 14• 37 Transition cell carcinoma is the most common bladder tumor of dogs.

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It may be single, multiple, local, or diffuse. 5 •

17• 30• 37 It may occur as a papillary projection into the lumen of the bladder or it may infiltrate into the wall. Squamous cell carcinomas and adenocarcinomas also may occur and probably develop as a result of metaplasia of transitional cells. 5 • 17• 24• 37 Although some adenocarcinomas of urachal origin may occur in the dome of the bladder, most tumors are either widespread or occur in the neck region. 5 Bladder tumors should be staged according to the tumor, node, metastasis (TNM) system. 9 Poorly differentiated tumors with distant metastasis has the worst prognosis; superficial solitary well-differentiated tumors have the best prognosis. 9 · 37 Bladder tumors should be suspected in any older animal with hematuria, pollakiuria, dysuria, and/or incontinence that is not ·Tesponsive to antibiotic or other routine therapy. Bladder masses can be identified by contrast cystography or bladder ultrasonography. Definitive diagnosis is based on histopathologic evaluation of a bladder biopsy. This biopsy may be obtained via cystoscopy, laparoscopy, cystotomy, or by catheter biopsy. Cytologic evaluation of urine sediment or needle aspiration of the bladder mass may provide firm evidence of neoplasia. 9 Successful treatment of bladder tumors is primarily dependent on early diagnosis. Unfortunately, most of the time canine bladder tumors are not identified until the disease is well advanced. Therapy, therefore, is often aimed at relieving urinary discomfort, maintaining urinary continence, and preventing hydronephrosis and hydroureter. Curative treatment is rarely attainable. Surgically accessible tumors should be removed along with a wide zone of healthy tissue. Widespread tumors or tumors involving the neck region may be debulked. Total cystectomy with urinary diversion may be attempted, but in genera] it is not performed. Nonsurgical therapy includes radiation and chemotherapy. We are currently using, at the University of Illinois Veterinary Teaching Hospital, some combination of intravesicular and parenteral cisplatin and/or doxorubicin along with intravesicular hyperthermia. Symptomatic therapy includes the treatment of secondary urinary tract infection and urolithiasis and chemically cauterizing the bladder to stop bleeding. Methenamine mandelate (10 mg per kg given orally every 6 hours) or intravesicular instillation of a dilute formalin solution may cauterize the bladder. 9 • 26 Very little information is available concerning the life expectancy of dogs with bladder tumors that were treated with the newer chemotherapeutic modalities. Older information would indicate that life expectancy after diagnosis is less than 1 year. 5 However, in the one study that looked critically at life expectancy after diagnosis, only a small percentage of dogs were treated. 5 The majority were euthanized at diagnosis. As we start treating more of these dogs with appropriate and proven chemotherapeutic regimens, we will be better able to assess prognosis.

PROSTATE DISEASE Many prostate disorders occur in older animals. Prostate disease is most common in dogs older than 5 years. 20 Average age of occurrence has

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Table 1. Signs and Prostate Appearance Associated with Canine Prostate Diseases PROSTATE PROSTATE DISEASE

Benign hyperplasia Cystic hyperplasia

Acute bacterial prostatitis Chronic bacterial prostatitis Prostate abscessation

Prostatic neoplasia

SIGNS

None or straining to defecate, ribbonlike stools Urethral discharge, straining to defecate, ribbonlike stools, dysuria Fever, lethargy, painful urination and defecation Recurring urinary tract infections Recurring urinary tract infection, ribbonlike stools, painful defecation and urination, colon and urinary obstruction, fever, lethargy Colon and urinary obstruction, rear limb lameness

APPEARANCE

Symmetrically enlarged and firm Asymmetrically enlarged with fluctuant swelling Symmetrically enlarged and painful Symmetrically enlarged and nonpainful Asymmetrically enlarged, may contain a fluctuant swelling

Asymmetrically enlarged, firm, attached to pelvic canal

been reported to be 9. 3 years. 20 Prostatic cancer is seen primarily in dogs older than 10 years of age. 20 In general, the prostate responds to disease by becoming enlarged. Prostates can become enlarged as a result of hyperplasia, acute or chronic infection, abscessation, cyst formation (cystic hyperplasia and paraprostatic cyst), and neoplasia. 1• 13• 19· 20· 22 Enlarged prostates can produce disease by inducing either urinary pr Qolon obstruction due to pressure from the enlarged gland. Cystic hyperplasia and infection will often produce a urethral discharge. 1· 13· 19· 20· 22 Acute infection can result in septicemia, fever, and an extremely painful prostate. 1• 13· 19• 20• 22 Chronic bacterial prostate infections will often be found in animals being seen for the problem of recurring lower urinary tract infection. 1 Prostate abscesses must be differentiated from prostatic cysts in order to provide appropriate therapy. Prostate cancer can occur in either intact or neutered dogs .28 All adult male dogs should have a rectal examination to assess the prostate for size, shape, symmetry, surface contour, consistency, moveability, and pain. Findings will depend on the type of prostate disease (Table 1).1, 13, 19. 20. 22. 2s Prostate disease can be definitively identified by selecting the appropriate diagnostic evaluation. A complete blood count will aid in the diagnosis of acute prostatitis because this disease will produce systemic inflammation. Ultrasound evaluation of the prostate can identify cystic areas but cannot differentiate cyst formation from abscessation. Evaluating prostatic fluid by culture and cytology can be used to identify infectious inflammation and

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neoplasia. Prostate fluid can be obtained by collecting the third fraction of an ejaculation or by prostatic massage. 3 Needle aspiration, catheter biopsy, or surgical biopsy followed by cytologic or histologic evaluation can be used to identify prostatic neoplasia. Appropriate treatment of prostatic disease depends on the cause. Acute prostatitis is treated with an appropriate antibiotic as determined by a culture and sensitivity. The prostatic blood barrier is broken in this instance, so the antibiotic need not be one that can cross this barrier. Chronic prostatitis is also treated with an antibiotic chosen from a culture and sensitivity, but in this instance, the antibiotic must be one that will cross the prostatic blood barrier (trimethoprim plus sulfadiazine, erythromycin, chloramphenicol, lincomycin, clindamycin, oleandomycin). 1• 2• 20 Abscesses, cysts, and neoplasia must be treated surgically. Abscesses should be excised or drained. 2• 21 Cysts should be SQrgically resected. 19 Neoplasia should be treated with either partial or total prostatic resection. 19· 21 Castration is recommended for all dogs with prostate disease unless they are breeding animals. 1• 19 Prostatic hyperplasia will regress soon after neutering. Chronic and acute infection will often recur even with appropriate antibiotic therapy unless the animal is neutered and some prostatic neoplasia may grow under the influence of testosterone. However, even if dogs with prostate disease are castrated, serial follow-up examinations are indicated to ensure remission of the disease.

SUMMARY

Disorders of the urinary system are common in geriatric dogs. Common urinary disorders that are seen in older dogs include chronic renal failure, urinary incontinence, bladder tumors, and prostate problems. Therapy for chronic renal failure is aimed at both slowing the progression of the disease and ameliorating the signs of uremia. Therapeutic recommendations for the conservative medical management of chronic renal failure include reducing dietary protein, moderately reducing salt intake, maintaining normal serum phosphorus levels, providing free access to water, avoiding stress, supplementing water soluble vitamins, using anabolic steroids to treat the anemia of chronic renal failure, treating acidosis, and controlling hypocalcemia. Urinary incontinence can often be controlled or eliminated. The appropriate approach to management of this disorder is to identify and remove specific causes. Common causes of urinary incontinence are urethral incompetence, urinary tract infection, and polyuria and polydypsia. Bladder tumors are, fortunately, not a common tumor of dogs, but are more common in geriatric dogs than in the young. The most common bladder tumor is the transitional cell carcinoma. Therapy for this tumor is usually palliative because of its malignant nature and because it is usually located in the neck of the bladder. Its location in the bladder often makes it impossible to resect the tumor completely without removing the entire bladder and diverting the ureters. New chemotherapeutic modalities are being evaluated that may increase life expectancy after diagnosis and, therefore, improve prognosis.

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Prostate disease is also seen in older dogs. Types of prostate abnormalities seen in dogs include prostatic hyperplasia, oysts, abscesses, acute and chronic infection, and neoplasia. The institution of proper therapy requires an accurate diagnosis; neutering is often recommended as a part of therapy regardless of the type of prostatic disease present.

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Pract] 9:679-700, 1979 2. Barsanti JA, Finco DR: Treatment of bacterial prostatitis. In Kirk RW (ed): Current Veterinary Therapy VIII. Philadelphia, WB Saunders, 1983, pp 1101-1104 3. Barsanti JA, Prasse KW, Crowell WA, eta!: Evaluation of various techniques for diagnosis of chronic bacterial prostatitis in the dog. J Am Vet Med Assoc 183:219-224, 1983 4. Brenner BM, Meyer TW, Hostetter TH: Dietary protein intake and the progressive nature of kidney disease: The role of hemodynamically mediated glomerular injury in the pathogenesis of progressive glomerular sclerosis in aging, renal ablation and intrinsic renal disease. N Eng! J Med 307:652-659, 1982 5. Burnie AG, Weaver AD: Urinary bladder neoplasia in the dog: A review of seventy cases. J Small Anim Pract 24:129- 143, 1983 6. Chew DJ, DiBartola SP, Fenner WR: Pharmacologic manipulation of urination. In Kirk RW (ed): Current Veterinary Therapy IX. Philadelphia, WB Saunders, 1986, pp 12071212 7. Cowgill LD, Kallet AJ: Recognition and management of hypertension in the dog. In Kirk RW (ed): Current Veterinary Therapy XIII. Philadelphia, WB Saunders, 1983, pp 1025-1028 8. Cowgill LD, Spangler WL: Renal insufficiency in geriatric dogs. Vet Clin North Am [Small Anim Pract]11:727- 748, 1981 9. Crow SE, Klausner JS: Management of transitional cell carcinomas of the urinary bladder. In Kirk RW (ed): Current Veterinary Therapy VIII. Philadelphia, WB Saunders, 1983, pp 1119- 1121 10. DiBartola SP, Adams WM: Urinary incontinence associated with malposition of the urinary bladder. In Kirk RW (ed): Current Veterinary Therapy VIII. Philadelphia, WB . ... Saunders, 1983, pp 1089.,-1092 11. Fined DR: The role of phosphorus restriction in the managemenf':o(~bronic renal failure in the dog and cat. In The Seventh Annual Kal Kan Symposium fur the Treatment of Small Animal Diseases. Vernon, CA, Kal Kan Foods Inc. , 1983, !pp 131- 133 12. Finco DR, Barsanti JA: Treatment of mineral imbalances of chronic renal failure. In Kirk RW (ed): Current Veterinary Therapy XIII. Philadelphia, WB Saunders, 1983, pp 1019-1021 13. Greiner TP, Johnson RG: Diseases of the prostate gland. In Ettinger SJ (ed): Textbook of Veterinary Internal Medicine. Philadelphia, WB Saunders, 1983, pp 1459-1492 14. Grognet J: Transitional cell carcinoma and subsequent rupture of the canine bladder: A case report and review of the literature. Can Vet J 24:338-340, 1983 15. Hardy RM : Disorders of water metabolism. Vet Clin North Am [Small Anim Pract] 12:353-373, 1982 16. Hardy RM , Osborne CA: Water deprivation and vasopressin concentration tests in the differentiation of polyuric syndromes. In Kirk RW (ed): Current Veterinary Therapy VII. Philadelphia, WB Saunders, 1980, pp 1080- 1085 17. Hayes HM: Canine bladder cancer: Epidemiologic features. Am J Epidemiol 104:673677, 1976 18. Hayes HM, Hoover R, Tarone RE: Bladder cancer in pet dogs: A sentinel for environmental cancer? Am J Epidemiol 114:229- 233, 1981 19. Hornbuckle WE, Kleine LJ: Medical management of prostatic disease. In Kirk RW (ed): Current Veterinary Therapy VII. Philadelphia, WB Saunders, 1980, pp 1146- 1150 20. Hornbuckle WE, MacCoy DM, Allan GA, et al: Prostatic disease in the dog. Cornell Vet 68(suppl 7):284- 305, 1978

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21. Knecht CD: Diseases of the canine prostate gland (Part I). Compend Contin Ed Pract Vet 1:385-391, 1979 22. Knecht CD: Diseases of the canine prostate gland (Part II). Surgical Techniques. Compend Contin Ed Pract Vet 1:426-432, 1979 23. Krawiec DR: Diagnosis and treatment of acquired canine urinary incontinence. Comp Anim Pract, in press. 24. Krawiec, DR: Urinary incontinence in dogs and cats. Mod Vet Pract 69:17-24, 1988 25. Lewis LD, Morris ML Jr, Hand MS: Small Animal Nutrition Ill. Topeka, KS, Mark Morris Associates, 1987 26. Macy DW: Chemotherapeutic agents available for cancer treatment. ln Kirk RW (ed): Current Veterinary Therapy IX. Philadelphia, WB Saunders, 1986, pp 467-470 27. Moreau PM: Neurogenic disorders of micturition in the dog and cat. Compend Conlin Ed Pract Vet 4:12-21, 1982 28. Obradovich J, Walshaw R, Goullaud E: The influence of castration on the development of prostatic carcinoma in the dog. J Vet Intern Med 1:183- 187, 1987 29. Osborne CA, Klausner JS, Lees GE: Urinary tract infections: Normal and abnormal host defense mechanisms. Vet Clin North Am [Small Anim Pract] 9:587-609, 1979 30. Osborne CA, Low DC, Perman V, et a!: Neoplasms of the canine and feline urinary bladder: Incidence, etiologic factors , occurrence and pathologic features. Am J Vet Res 29:2041-2055, 1968 31. Osborne CA, Oliver JE, Polzin DE: Non-neurogenic urinary incontinence. In Kirk RW (ed): Current Veterinary Therapy VII. Philadelphia, WB Saunders, 1980, pp 1128-1136 32. Polzin DJ, Osborne CA: Conservative medical management of canine chronic polyuric renal failure. In Kirk RW (ed): Current Veterinary Therapy XIII. Philadelphia, WB Saunders, 1983, pp 997-1007 33. Polzin DJ, Osborne CA: Updat~onservative medical management of chronic renal failure. In Kirk RW (ed): Current Veterinary Therapy IX. Philadelphia, WB Saunders, 1986, pp 1167-1173 34. Rosin AE, Barsanti JA: Diagnosis of urinary incontinence in dogs: Role of the urethral pressure profile. JAm Vet Med Assoc 178:814-822, 1981 35. Samiy AH: Clinical manifestations of disease in the elderly. Med Clin North Am 67:333344, 1983 36. Samiy AH: Renal disease in the elderly. Med Clin North Am 67:463-480, 1983 37. Theilen GH, Madewell BR: Tumors of the urogen'ital tract. In Theilen GH, Madwell BR (eds): Veterinary Cancer Medicine. Philadelphia, Lea & Febiger, 1979, pp 357-367 38. Wiseman MJ, Hunt R, Goodwin A, et al: Dietary composition and renal function in healthy subjects. Nephron 46:37-42, 1987 Department of Veterinary Clinical Medicine College of Veterinary Medicine University of Illinois Urbana, IL 61801