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Applications of diagnostic ultrasonography in small ruminant reproductive management
Animal Reproduction Science 130 (2012) 184–186
Contents lists available at SciVerse ScienceDirect
Animal Reproduction Science journal homepage: www.elsevier.com/locate/anireprosci
Applications of diagnostic ultrasonography in small ruminant reproductive management夽 P.R. Scott University of Edinburgh, Easter Bush Veterinary Centre, Roslin, Midlothian, Scotland, United Kingdom
a r t i c l e
i n f o
Article history: Available online 25 January 2012 Keywords: Fertility Pregnancy diagnosis Reproduction Small ruminant Ultrasonography
a b s t r a c t Modern portable ultrasound machines provide the veterinary clinician with an inexpensive and non-invasive method to further examine the reproductive tract of both male and female sheep on farm which should take no more than 5 min with the results available immediately. Unlike cattle, ultrasound examination of the ovaries is not undertaken because failure to cycle during the normal season is rare in sheep and there are no common ovarian conditions causing acyclicity. Accurate diagnosis of foetal number has greatly improved the nutritional management of late gestation ewes over the past 30 years. Late gestation nutritional supply in response to foetal demand greatly reduces perinatal lamb mortality by ensuring lamb birthweight and ewe colostrum accumulation. The contents of vaginal prolapse have been determined using ultrasonography which has led to an improved method for correction. A retained foetus when second stage labour is considered to have been completed, and uterine torsion, can be identified during ultrasound examination allowing timely correction. Ultrasonographic examination of palpable scrotal abnormalities can provide much useful information particularly in the diagnosis of epididymitis, orchitis and testicular atrophy. © 2012 Elsevier B.V. All rights reserved.
1. Introduction Many veterinarians in cattle practice routinely employ ultrasonographic examination using 5 MHz linear array scanners transrectally for examination of the ovaries and uterus, as well as for the early detection, and possibly sexing, of bovine embryos. This equipment can also be employed to provide diagnostic quality ultrasound images of the gravid ovine or caprine uterus, yielding immediate results; in these species, examination of the ovaries is rarely undertaken. A 5 MHz linear array scanner can also be used for ultrasound examination of the scrotum.
夽 This paper is part of the special issue entitled: Reproductive Health Management of Sheep and Goats, Guest Edited by G.S. Amiridis and G.C. Fthenakis. E-mail address: [email protected] 0378-4320/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.anireprosci.2012.01.013
2. Methodologies for diagnostic ultrasonography in small ruminant reproduction 2.1. Bladder, uterus, vagina and ventral abdomen The absence of fleece in the ventral midline and inguinal area expedites preparation when examining the ventral and caudal abdomen in sheep. Ultrasonographic examination of the bladder and caudal abdomen are undertaken in the standing animal, by using either 5.0 MHz linear array or sector scanners (10 cm versus 20 field depth, respectively). The caudal abdomen is examined for the bladder and gravid uterus. The right inguinal region immediately cranial to the pubis is cleaned with a mild detergent solution diluted in warm tap water to remove superficial grease and debris. The right inguinal region is chosen, because the left side of the abdomen is largely occupied by the rumen. Ultrasound gel is liberally applied to the wet skin to ensure good contact. The transducer head is firmly held at right angles against the abdominal wall to image the uterus.
P.R. Scott / Animal Reproduction Science 130 (2012) 184–186
2.2. Obstetrical problems The contents of the vaginal prolapse can be readily determined using real-time B-mode ultrasonography with a 5 MHz transducer and either linear array or sector scanners (Scott and Gessert, 1998a,b). 2.3. Scrotal contents Sequential examination of the pampiniform plexus, the head of the epididymis, the testis and the tail of the epididymis is undertaken, as the linear array scanner is moved distally over the lateral aspect of the scrotum.
3. Findings in diagnostic ultrasonography in small ruminant reproduction 3.1. Pregnancy, gestation stage and foetal numbers Ultrasonography has been successfully employed in commercial flocks for the past 30 years to determine foetal numbers and gestation stage, permitting more precise feeding and management during late gestation (Fowler and Wilkins, 1984; White et al., 1984; Russel, 1985). Real time transrectal ultrasonographic scanning of sheep applied between 24th and 34th day of gestation offers a safe, accurate and practical means for diagnosing pregnancy (Garcia et al., 1993). Accuracies of diagnosis of pregnancy of over 99%, of differentiation of non-pregnant, singleand multiple-bearing ewes of 98% and of determination of actual foetal numbers of 97% can be achieved in practice at scanning rates of at least one ewe per minute (White et al., 1984). 3.2. Obstetrical problems Ultrasonographic examination is of particular value, when transabdominal ballotment suggests the presence of a foetus in utero after delivery of lamb(s) some 12–48 h previously, but contraction of the cervix prevents further manual examination of the uterus (Scott and Gessert, 2000). This situation may be compounded when the number of lambs delivered is less than the foetal number determined during a mid-pregnancy examination. It can prove difficult to differentiate the contracted uterus from a uterine horn containing a single lamb by transabdominal ballotment alone, but this problem can be easily resolved by ultrasonographic examination of the caudal abdomen. Ultrasonography has been used to monitor uterine involution post-partum, which was delayed in ewes after manual correction of dystocia and caesarean section (Hauser and Bostedt, 2002). Uterine torsion is a problematic diagnosis in sheep, because vaginal examination is restricted by the narrow diametre of the reproductive tract and will not identify a torsion involving the body of the uterus cranial to the cervix. Recent work has described the application of transabdominal ultrasound examination of the uterine wall as
185
close to the cervix as possible (ventral midline immediately cranial to the pelvic brim with the probe head directed vertically) as a non-invasive means of detecting uterine torsion in sheep (Wehrend et al., 2002). Oedema of the uterine wall following torsion resulted in a doubling of the thickness from 5 mm to over 10 mm. Whilst a 7.5 MHz scanner was used in this investigation, a 5 MHz linear scanner should provide diagnostic quality sonograms. The early recognition of this condition and delivery of the lambs by caesarean section should significantly improve the surgical outcome (Scott, 1989). Vaginal prolapse may contain the dorsal vaginal wall, urinary bladder, uterine horn(s) or both urinary bladder and uterine horn(s). Urinary bladder is readily identified as an anechoic (black) area on the sonogram, usually greater than 10 cm in diametre and compressed dorso-ventrally. A fold in the bladder wall, which presents as a hyperechoic (white) line, can often be visualized in the ventral one-third of the anechoic area. Sections through the tips of uterine horn(s) appear as anechoic circles measuring 3–5 cm in diametre bordered by the hyperechoic uterine wall; caruncles are not usually observed. 3.3. Scrotal contents The pampiniform plexus is clearly visible as a collection of thin walled vessels (anechoic cylinders and circles bordered by hyperechoic walls). The normal testis appears as a uniform hypoechoic area with a hyperechoic mediastinum clearly visible. The tail of the epididymis is distinct from the testis and considerably smaller in diametre (2–3 cm compared to 6–7 cm) with an obvious capsule. The testis is much reduced in size (normal: >7 cm in diametre, frequently 5 cm for atrophy cases) and appears more hypoechoic than normal and contains many hyperechoic dots. These hyperechoic dots are thought to represent the fibrous supporting architecture, now more obvious due to atrophy of the seminiferous tubules. Ultrasonography was reported to be useful for the diagnosis of intra-scrotal abnormalities after experimental inoculation with Arcanobacterium pyogenes into the testicle, especially during investigation of the long-standing stage of the disease after clinical findings had subsided (Gouletsou et al., 2004). Epididymitis caused by Brucella ovis or Actinobacillus seminis/Histophilus ovis is a major cause of ram infertility in many countries. Ultrasonographic examination in rams with epididymitis reveals a normal pampiniform plexus. Typically, the swollen scrotal contents frequently appear as multiple 1–5 cm diametre anechoic areas, containing many bright spots surrounded by broad hyperechoic lines (fibrous capsule), which extend up to 1 cm in thickness typical of thick-walled abscesses. The abscesses generally involve the tail of the epididymis, but may extend to involve the body and head of the epididymis, respectively. The testis is embedded within fibrous tissue reaction and is much reduced in size and appears more hypoechoic than normal and contains many hyperechoic spots consistent with testicular atrophy (Karaca et al., 1999). In unilateral epididymitis, the contralateral testicle is
186
P.R. Scott / Animal Reproduction Science 130 (2012) 184–186
much smaller than normal and appears more hypoechoic. 4. Concluding remarks Ultrasonography has been used most successfully in small ruminant reproductive management to determine foetal number in mid-pregnancy, thereby ensuring adequate energy supply during the final six weeks of gestation. The speed and very high accuracy of the operators have ensured the widespread uptake of this technique by sheep producers in many countries. Such targeted nutrition has major economic and animal welfare benefits. Combined with ewe energy status evaluation using hydroxybutyrate measurement (Russel, 1985), ultrasound examination to determine foetal load is the most important veterinary advice for farmers regarding the management of pregnant ewes and the benefits of such expertise cannot be over-emphasised. Moreover, use of ultrasonography during breeding evaluation of rams/buck offers an accurate, non-invasive technique additionally to the clinical examination of the genitalia. Finally, diagnostic ultrasonography (Scott and Sargison, 2010) can be employed successfully for disorders of the genital tract of female (particularly of obstetrical problems) and male animals. Conflict of interest statement The author has nothing to disclose.
References Fowler, D.G., Wilkins, J.F., 1984. Diagnosis of pregnancy and number of foetuses in sheep by real time ultrasound imaging. 1. Effect of number of foetuses, stage of gestation, operator, and breed of ewe on accuracy of diagnosis. Liv. Prod. Sci. 11, 437–450. Garcia, A., Neary, M.K., Kelly, G.R., Pierson, R.A., 1993. Accuracy of ultrasonography in early pregnancy diagnosis in the ewe. Theriogenology 39, 847–861. Gouletsou, P.G., Fthenakis, G.C., Cripps, P.J., Papaioannou, N., Lainas, T., Psalla, D., Amiridis, G.S., 2004. Experimentally induced orchitis associated with Arcanobacterium pyogenes: clinical, ultrasonographic, seminological and pathological features. Theriogenology 62, 1307–1328. Hauser, B., Bostedt, H., 2002. Ultrasonographic observations of the uterine regression in the ewe under different obstetrical conditions. J. Vet. Med. A 49, 511–516. Karaca, F., Aksoy, M., Kaya, A., Atsaman, M.B., Tekeli, T., 1999. Spermatic granuloma in the ram: diagnosis by ultrasonography and semen characteristics. Vet. Radiol. Ultrasound 40, 402–406. Russel, A., 1985. Nutrition of the pregnant ewe. In Pract. 7, 23–29. Scott, P.R., 1989. Ovine caesarean operations: a study of 137 field cases. Br. Vet. J. 145, 558–564. Scott, P.R., Gessert, M.E., 1998a. Management of ovine vaginal prolapse in general practice. In Pract. 20, 28–34. Scott, P.R., Gessert, M.E., 1998b. Ultrasonographic examination of 12 ovine vaginal prolapses. Vet. J. 155, 323–324. Scott, P.R., Gessert, M.E., 2000. Application of ultrasonographic examination of the ovine foetus in normal sheep and those presenting with obstetrical problems. Vet. J. 159, 291–292. Scott, P.R., Sargison, N.D., 2010. Ultrasonography as an adjunct to clinical examination in sheep. Small Rumin. Res. 92, 108–199. Wehrend, A., Bostedt, H., Burkhardt, E., 2002. The use of trans-Abdominal B mode ultrasonography to diagnose intra-partum uterine torsion in the ewe. Vet. J. 176, 69–70. White, I.R., Russel, A.J., Fowler, D.G., 1984. Real-time ultrasonic scanning in the diagnosis of pregnancy and the determination of fetal numbers in sheep. Vet. Rec. 115, 140–143.
Contents lists available at SciVerse ScienceDirect
Animal Reproduction Science journal homepage: www.elsevier.com/locate/anireprosci
Applications of diagnostic ultrasonography in small ruminant reproductive management夽 P.R. Scott University of Edinburgh, Easter Bush Veterinary Centre, Roslin, Midlothian, Scotland, United Kingdom
a r t i c l e
i n f o
Article history: Available online 25 January 2012 Keywords: Fertility Pregnancy diagnosis Reproduction Small ruminant Ultrasonography
a b s t r a c t Modern portable ultrasound machines provide the veterinary clinician with an inexpensive and non-invasive method to further examine the reproductive tract of both male and female sheep on farm which should take no more than 5 min with the results available immediately. Unlike cattle, ultrasound examination of the ovaries is not undertaken because failure to cycle during the normal season is rare in sheep and there are no common ovarian conditions causing acyclicity. Accurate diagnosis of foetal number has greatly improved the nutritional management of late gestation ewes over the past 30 years. Late gestation nutritional supply in response to foetal demand greatly reduces perinatal lamb mortality by ensuring lamb birthweight and ewe colostrum accumulation. The contents of vaginal prolapse have been determined using ultrasonography which has led to an improved method for correction. A retained foetus when second stage labour is considered to have been completed, and uterine torsion, can be identified during ultrasound examination allowing timely correction. Ultrasonographic examination of palpable scrotal abnormalities can provide much useful information particularly in the diagnosis of epididymitis, orchitis and testicular atrophy. © 2012 Elsevier B.V. All rights reserved.
1. Introduction Many veterinarians in cattle practice routinely employ ultrasonographic examination using 5 MHz linear array scanners transrectally for examination of the ovaries and uterus, as well as for the early detection, and possibly sexing, of bovine embryos. This equipment can also be employed to provide diagnostic quality ultrasound images of the gravid ovine or caprine uterus, yielding immediate results; in these species, examination of the ovaries is rarely undertaken. A 5 MHz linear array scanner can also be used for ultrasound examination of the scrotum.
夽 This paper is part of the special issue entitled: Reproductive Health Management of Sheep and Goats, Guest Edited by G.S. Amiridis and G.C. Fthenakis. E-mail address: [email protected] 0378-4320/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.anireprosci.2012.01.013
2. Methodologies for diagnostic ultrasonography in small ruminant reproduction 2.1. Bladder, uterus, vagina and ventral abdomen The absence of fleece in the ventral midline and inguinal area expedites preparation when examining the ventral and caudal abdomen in sheep. Ultrasonographic examination of the bladder and caudal abdomen are undertaken in the standing animal, by using either 5.0 MHz linear array or sector scanners (10 cm versus 20 field depth, respectively). The caudal abdomen is examined for the bladder and gravid uterus. The right inguinal region immediately cranial to the pubis is cleaned with a mild detergent solution diluted in warm tap water to remove superficial grease and debris. The right inguinal region is chosen, because the left side of the abdomen is largely occupied by the rumen. Ultrasound gel is liberally applied to the wet skin to ensure good contact. The transducer head is firmly held at right angles against the abdominal wall to image the uterus.
P.R. Scott / Animal Reproduction Science 130 (2012) 184–186
2.2. Obstetrical problems The contents of the vaginal prolapse can be readily determined using real-time B-mode ultrasonography with a 5 MHz transducer and either linear array or sector scanners (Scott and Gessert, 1998a,b). 2.3. Scrotal contents Sequential examination of the pampiniform plexus, the head of the epididymis, the testis and the tail of the epididymis is undertaken, as the linear array scanner is moved distally over the lateral aspect of the scrotum.
3. Findings in diagnostic ultrasonography in small ruminant reproduction 3.1. Pregnancy, gestation stage and foetal numbers Ultrasonography has been successfully employed in commercial flocks for the past 30 years to determine foetal numbers and gestation stage, permitting more precise feeding and management during late gestation (Fowler and Wilkins, 1984; White et al., 1984; Russel, 1985). Real time transrectal ultrasonographic scanning of sheep applied between 24th and 34th day of gestation offers a safe, accurate and practical means for diagnosing pregnancy (Garcia et al., 1993). Accuracies of diagnosis of pregnancy of over 99%, of differentiation of non-pregnant, singleand multiple-bearing ewes of 98% and of determination of actual foetal numbers of 97% can be achieved in practice at scanning rates of at least one ewe per minute (White et al., 1984). 3.2. Obstetrical problems Ultrasonographic examination is of particular value, when transabdominal ballotment suggests the presence of a foetus in utero after delivery of lamb(s) some 12–48 h previously, but contraction of the cervix prevents further manual examination of the uterus (Scott and Gessert, 2000). This situation may be compounded when the number of lambs delivered is less than the foetal number determined during a mid-pregnancy examination. It can prove difficult to differentiate the contracted uterus from a uterine horn containing a single lamb by transabdominal ballotment alone, but this problem can be easily resolved by ultrasonographic examination of the caudal abdomen. Ultrasonography has been used to monitor uterine involution post-partum, which was delayed in ewes after manual correction of dystocia and caesarean section (Hauser and Bostedt, 2002). Uterine torsion is a problematic diagnosis in sheep, because vaginal examination is restricted by the narrow diametre of the reproductive tract and will not identify a torsion involving the body of the uterus cranial to the cervix. Recent work has described the application of transabdominal ultrasound examination of the uterine wall as
185
close to the cervix as possible (ventral midline immediately cranial to the pelvic brim with the probe head directed vertically) as a non-invasive means of detecting uterine torsion in sheep (Wehrend et al., 2002). Oedema of the uterine wall following torsion resulted in a doubling of the thickness from 5 mm to over 10 mm. Whilst a 7.5 MHz scanner was used in this investigation, a 5 MHz linear scanner should provide diagnostic quality sonograms. The early recognition of this condition and delivery of the lambs by caesarean section should significantly improve the surgical outcome (Scott, 1989). Vaginal prolapse may contain the dorsal vaginal wall, urinary bladder, uterine horn(s) or both urinary bladder and uterine horn(s). Urinary bladder is readily identified as an anechoic (black) area on the sonogram, usually greater than 10 cm in diametre and compressed dorso-ventrally. A fold in the bladder wall, which presents as a hyperechoic (white) line, can often be visualized in the ventral one-third of the anechoic area. Sections through the tips of uterine horn(s) appear as anechoic circles measuring 3–5 cm in diametre bordered by the hyperechoic uterine wall; caruncles are not usually observed. 3.3. Scrotal contents The pampiniform plexus is clearly visible as a collection of thin walled vessels (anechoic cylinders and circles bordered by hyperechoic walls). The normal testis appears as a uniform hypoechoic area with a hyperechoic mediastinum clearly visible. The tail of the epididymis is distinct from the testis and considerably smaller in diametre (2–3 cm compared to 6–7 cm) with an obvious capsule. The testis is much reduced in size (normal: >7 cm in diametre, frequently 5 cm for atrophy cases) and appears more hypoechoic than normal and contains many hyperechoic dots. These hyperechoic dots are thought to represent the fibrous supporting architecture, now more obvious due to atrophy of the seminiferous tubules. Ultrasonography was reported to be useful for the diagnosis of intra-scrotal abnormalities after experimental inoculation with Arcanobacterium pyogenes into the testicle, especially during investigation of the long-standing stage of the disease after clinical findings had subsided (Gouletsou et al., 2004). Epididymitis caused by Brucella ovis or Actinobacillus seminis/Histophilus ovis is a major cause of ram infertility in many countries. Ultrasonographic examination in rams with epididymitis reveals a normal pampiniform plexus. Typically, the swollen scrotal contents frequently appear as multiple 1–5 cm diametre anechoic areas, containing many bright spots surrounded by broad hyperechoic lines (fibrous capsule), which extend up to 1 cm in thickness typical of thick-walled abscesses. The abscesses generally involve the tail of the epididymis, but may extend to involve the body and head of the epididymis, respectively. The testis is embedded within fibrous tissue reaction and is much reduced in size and appears more hypoechoic than normal and contains many hyperechoic spots consistent with testicular atrophy (Karaca et al., 1999). In unilateral epididymitis, the contralateral testicle is
186
P.R. Scott / Animal Reproduction Science 130 (2012) 184–186
much smaller than normal and appears more hypoechoic. 4. Concluding remarks Ultrasonography has been used most successfully in small ruminant reproductive management to determine foetal number in mid-pregnancy, thereby ensuring adequate energy supply during the final six weeks of gestation. The speed and very high accuracy of the operators have ensured the widespread uptake of this technique by sheep producers in many countries. Such targeted nutrition has major economic and animal welfare benefits. Combined with ewe energy status evaluation using hydroxybutyrate measurement (Russel, 1985), ultrasound examination to determine foetal load is the most important veterinary advice for farmers regarding the management of pregnant ewes and the benefits of such expertise cannot be over-emphasised. Moreover, use of ultrasonography during breeding evaluation of rams/buck offers an accurate, non-invasive technique additionally to the clinical examination of the genitalia. Finally, diagnostic ultrasonography (Scott and Sargison, 2010) can be employed successfully for disorders of the genital tract of female (particularly of obstetrical problems) and male animals. Conflict of interest statement The author has nothing to disclose.
References Fowler, D.G., Wilkins, J.F., 1984. Diagnosis of pregnancy and number of foetuses in sheep by real time ultrasound imaging. 1. Effect of number of foetuses, stage of gestation, operator, and breed of ewe on accuracy of diagnosis. Liv. Prod. Sci. 11, 437–450. Garcia, A., Neary, M.K., Kelly, G.R., Pierson, R.A., 1993. Accuracy of ultrasonography in early pregnancy diagnosis in the ewe. Theriogenology 39, 847–861. Gouletsou, P.G., Fthenakis, G.C., Cripps, P.J., Papaioannou, N., Lainas, T., Psalla, D., Amiridis, G.S., 2004. Experimentally induced orchitis associated with Arcanobacterium pyogenes: clinical, ultrasonographic, seminological and pathological features. Theriogenology 62, 1307–1328. Hauser, B., Bostedt, H., 2002. Ultrasonographic observations of the uterine regression in the ewe under different obstetrical conditions. J. Vet. Med. A 49, 511–516. Karaca, F., Aksoy, M., Kaya, A., Atsaman, M.B., Tekeli, T., 1999. Spermatic granuloma in the ram: diagnosis by ultrasonography and semen characteristics. Vet. Radiol. Ultrasound 40, 402–406. Russel, A., 1985. Nutrition of the pregnant ewe. In Pract. 7, 23–29. Scott, P.R., 1989. Ovine caesarean operations: a study of 137 field cases. Br. Vet. J. 145, 558–564. Scott, P.R., Gessert, M.E., 1998a. Management of ovine vaginal prolapse in general practice. In Pract. 20, 28–34. Scott, P.R., Gessert, M.E., 1998b. Ultrasonographic examination of 12 ovine vaginal prolapses. Vet. J. 155, 323–324. Scott, P.R., Gessert, M.E., 2000. Application of ultrasonographic examination of the ovine foetus in normal sheep and those presenting with obstetrical problems. Vet. J. 159, 291–292. Scott, P.R., Sargison, N.D., 2010. Ultrasonography as an adjunct to clinical examination in sheep. Small Rumin. Res. 92, 108–199. Wehrend, A., Bostedt, H., Burkhardt, E., 2002. The use of trans-Abdominal B mode ultrasonography to diagnose intra-partum uterine torsion in the ewe. Vet. J. 176, 69–70. White, I.R., Russel, A.J., Fowler, D.G., 1984. Real-time ultrasonic scanning in the diagnosis of pregnancy and the determination of fetal numbers in sheep. Vet. Rec. 115, 140–143.