In cooperation with
Theriogenology Question of the Month History A 4-year-old 529-kg (1,164-lb) American Quarter Horse stallion was admitted on January 20, 2014, to the Texas Veterinary Medical Center at the Texas A&M University College of Veterinary Medicine for training to enable semen collection on a breeding dummy, a breeding soundness evaluation, and collection of ejaculates for semen cryopreservation. No abnormalities were noted during physical examination. The stallion displayed good libido toward an ovariectomized teaser mare, readily mounted a breeding dummy,a and ejaculated into a Missouri-model artificial vagina.b Two ejaculates were collected 1 hour apart. Results for the first and second ejaculates, respectively, were as follows: total spermatozoa motility (71% and 75%), progressive spermatozoa motility (56% and 58%), percentage of intact membranes (ie, viability; 64% and 73%), morphologically normal spermatozoa (57% and 81%), and total number of spermatozoa (2.66 X 109 and 3.83 X 109). The second ejaculate was believed to be a better representation of the quality of spermatozoa the stallion was capable of producing at that time. Manual examination of the external reproductive tract was performed following collection of the second ejaculate, and it revealed that the craniolateral portion of the right hemiscrotum was large. This enlargement was identified specifically as the right spermatic cord adjacent to the cranial half of the epididymis. The left hemiscrotum was unremarkable. Ultrasonographicc evaluation of the scrotal contents revealed that the right hemiscrotum contained a large, multiloculated, fluid-filled mass extending from the dorsocranial aspect of the testis along the spermatic cord to the right external inguinal ring. Doppler ultrasonography revealed that blood vessels in the spermatic cord were patent and appeared to be surrounded and compressed by fluid-filled structures (Figure 1). The cranial aspect of the parenchyma of the right testis had a moth-eaten polycystic pattern (ie, mixed echogenic pattern). The body and tail of the right epididymis appeared to be ultrasonographically normal, but the head of the right epididymis could not be identified and appeared to be continuous with the large, multiloculated mass. Volume of the left testis, estimated by use of ultrasonography, was 126.4 mL. Volume of the right testis was not measured. Daily sperm output for the left testis was estimated to be 1.77 X 109 spermatozoa to 2.27 X 109 spermatozoa. Transrectal palpation of the internal reproductive tract revealed that both internal inguinal rings were approximately 4.0 to 4.5 cm in diameter. No other abnormalities were detected. This report was submitted by Jared L. Voge, DVM, MS; John F. Edwards, DVM, PhD; Charles C. Love, DVM, PhD; and Terry L. Blanchard, DVM, MS; from the Departments of Large Animal Clinical Sciences (Voge, Love, Blanchard) and Veterinary Pathobiology (Edwards), College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843. Address correspondence to Dr. Voge ([email protected]). JAVMA, Vol 246, No. 8, April 15, 2015
Figure 1—Doppler ultrasonographic image of a multiloculated, fluid-filled mass compressing the blood vessels within the right spermatic cord of a 4-year-old American Quarter Horse stallion with a large right hemiscrotum. Tick marks at the bottom of the image are at intervals of 1 cm.
Eight additional ejaculates were collected over a period of 4 weeks for semen cryopreservation. The owner subsequently decided to use the stallion for breeding during the 2014 Northern Hemisphere breeding season. The stallion was discharged to the owner with a recommendation to monitor the right hemiscrotum for further enlargement as well as to have semen quality evaluated to detect any changes. Semen was collected multiple times from the stallion after it was discharged from our hospital (data on spermatozoa quality not available). The owner reported that an ejaculate collected at the farm 4 months after discharge from our hospital had no motile spermatozoa. On June 26, 2014 (1 week after collection of the semen sample with no motile spermatozoa), the stallion was readmitted to our hospital. Three ejaculates were collected, which had decreased spermatozoa quality (total spermatozoa motility, 48% to 57%; progressively motile spermatozoa, 38% to 51%; morphologically normal spermatozoa, 28% to 40%). However, total number of spermatozoa in the gel-free portion of the ejaculates (1.37 X 109 to 2.46 X 109) remained similar to results for the initial ejaculates. The moth-eaten appearance of the parenchyma of the right testis now extended over the entire dorsal surface of the testis, and the fluid-filled structures in the right hemiscrotum appeared larger and compressed the left testis. Question What are the most likely differential diagnoses for the enlarged scrotum of this stallion? Please turn the page. Vet Med Today: Theriogenology Question of the Month
847
Answer The list of differential diagnoses should include neoplasia (including mesothelioma), varicocele, spermatic cord torsion, or congenital malformation of the testicular or epididymal tubules. Results Six days after the stallion was readmitted to our hospital, surgery was performed. The stallion prophylactically received broad-spectrum antimicrobials (penicillin G procaine, 22,000 U/kg [10,000 U/lb], IM, once; and gentamicin, 6.6 mg/kg [3 mg/lb], IV, once) and flunixin meglumine (1.1 mg/kg [0.5 mg/lb], IV, q 24 h). Anesthesia was induced, and a right-side, open, unilateral orchiectomy was performed. Preanesthetic sedation and anesthesia were achieved with a combination of xylazine hydrochloride (1 mg/ kg [0.45 mg/lb, IV), diazepam (1 mg/kg, IV), and ketamine hydrochloride (2.2 mg/kg [1 mg/lb], IV). Sevoflurane in oxygen was used to maintain a surgical plane of anesthesia. A ligature of size-2 polyglactin 910d was placed around the cremaster muscle and spermatic cord. The cremaster muscle was transected distal to the ligature. An emasculatore was placed distal to the ligature but proximal to the enlarged spermatic cord. A second ligature of size-2 polyglactin 910 was placed on the spermatic cord proximal to the emasculatore but distal to the first ligature. The emasculator was removed 5 minutes after initial placement, and the spermatic cord was transected distal to the second ligature. Hemostasis was confirmed, and the remaining portion of the cremaster muscle and spermatic cord were placed into the abdomen through the right external inguinal ring. The external inguinal ring was closed with size2 polyglactin 910 in a simple continuous suture pattern. Subcutaneous tissues and the scrotal skin were closed with 2-0 poliglecapronef in a simple continuous suture pattern. After surgery, trimethoprim-sulfadiazine (5 mg of trimethoprim/kg [2.27 mg/lb] and 25 mg of sulfadiazine/kg [11.36 mg/lb], PO, q 24 h) was administered to the stallion. Twenty-four hours after surgery, moderate swelling of the prepuce was detected and treated with daily hand walking (15-minute sessions 3 times/d for 6 days). Administration of flunixin meglumine and trimethoprim-sulfadiazine was discontinued on days 3 and 5 after surgery, respectively. The right testis and spermatic cord were submitted for histologic examination. The right testis and spermatic cord measured 21 X 9.5 X 8 cm (Figure 2). Numerous variably sized, thin-walled, cystic structures filled with pale yellow fluid were located along the spermatic cord, head of the epididymis, and cranial portion of the testis, but they did not obstruct the epididymis. The epididymis appeared to be patent because spermatozoa were detected within the head and tail of the epididymis. The surgical procedure did not result in congestion of the fluid-filled areas; thus, it was assumed the cysts were not dilated veins or arteries. To differentiate lymphatic vessels (ie, endothelium) from testicular ducts, immunohistochemical 848
Vet Med Today: Theriogenology Question of the Month
analysis was performed with the markers factor VIII and cytokeratin. Most of the thin-walled cysts were lined by endothelium (factor VIII antigen-immunoreactive cells; Figure 3), which indicated that they were lymphatic vessels. However, scattered among the numerous lymphatic vessels were smaller, thin-walled, fluid-filled structures lined by a simple, cytokeratinimmunostained epithelium interpreted to be rete mediastinum without spermatids (Figure 4). Tissue containing the large and small fluid-filled cysts compressed the adjacent seminiferous tubules, which had mild degeneration (eg, many of the seminiferous tubules adjacent to the large and small fluid-filled cysts were devoid of germinal cells; Figure 5). Thus, it was presumed that degeneration was a result of compression by the cystic tissue; however, degeneration attributable to thermoregulatory problems could not be ruled out. Neoplasia was not observed. A histopathologic diagnosis of lymphangioma of the spermatic cord with secondary tubular ectasia of the rete mediastinum was made.
Figure 2—Photograph of the cross section of the right testis and spermatic cord of the stallion in Figure 1. Notice the cystic areas dorsal to the head of the epididymis. Bar = 1 cm. JAVMA, Vol 246, No. 8, April 15, 2015
Figure 5—Photomicrograph of lymphangioma cysts (L) with adjacent seminiferous tubules lacking round and elongated spermatids. H&E stain; bar = 500 µm.
Discussion Investigation of scrotal enlargement requires a thorough medical history and complete physical and reproductive examinations that include palpation and ultrasonography. In horses, a clinically normal scrotum has a distinct scrotal neck (ie, dorsal portion of the scrotum), and the testes and attached epididymides should be symmetric and freely movable within the scrotum. The tails of the epididymides should be positioned caudally within the scrotum, with the head and body of each epididymis located dorsolateral to the associated testis. Scrotal enlargement can originate from disease processes involving the scrotal skin, testes, epididymides, spermatic cords, or a combination of these structures or that involve the inguinal canals. In addition, extension of peritoneal processes to the scrotum via the inguinal canal should be considered. Thorough palpation and ultrasonographic evaluation of the scrotal contents should help differentiate the location from which the disease process originates. In the horse described here, the source of the scrotal enlargement (as determined on the basis of initial examination results) appeared to involve the right epididymis or spermatic cord. Disease processes that involve the epididymides or spermatic cords in stallions include inguinal herniation, varicocele, infectious or traumatic funiculitis or epididymitis, spermatic cord torsion, and neoplasia.1,2 The stallion described in the present report did not have a history of inguinal or scrotal injury; therefore, traumatic funiculitis or epididymitis were considered to be unlikely causes of the scrotal enlargement. In cases of acute or subacute infectious epididymitis, stallions usually have recurrent bouts of colic and palpation of the affected epididymis can elicit signs of pain.2 The stallion had no history of colic, the right epididymis was not excessively warm, and palpation of the right epididymis did not elicit signs of pain. Infectious funiculitis was considered unlikely because there were no signs of peritoneal involvement (ie, peritonitis). Inguinal herniation was ruled out because no intestinal loops were ultrasonographically visible in the scrotum or inguinal ring. Spermatic cord torsion, if severe (> 360º), can cause the testis, spermatic cord, and scrotum to enlarge because of venous congestion with resultant necrosis of the dependent testis.1 Spermatic cord torsion was ruled out on the basis of clinical findings and Doppler ultrasonographic detection of blood flow through the spermatic cord. On the basis of the stallion’s history and examination findings and the progressive nature of the lesion, the primary differential diagnoses prior to surgery were neoplasia (particularly mesothelioma), epididymal blockage, or varicocele. A definitive diagnosis could not be determined during the examinations. Because of the owner’s desire to use the stallion during the breeding season, and because the lesion did not appear to be affecting the quality of spermatozoa (which we assumed were produced by the contralateral testis), the owner elected to monitor the stallion’s condition. However, the lesion grew larger and presumably contributed to deterioration of spermatozoa quality; therefore, unilateral orchiectomy was performed. The testis and spermatic cord were sub-
JAVMA, Vol 246, No. 8, April 15, 2015
Vet Med Today: Theriogenology Question of the Month
Figure 3—Photomicrograph of factor VIII antigen–immunolabeled lymphangioma vessels that do not contain erythrocytes. Notice the blood vessel immunoreactive for factor VIII antigen (arrow). Factor VIII antigen immunolabel; bar = 40 µm.
Figure 4—Photomicrograph of cytokeratin-immunolabeled epithelial lining (arrow) of the rete testis that contains several spermatozoa heads surrounded by nonstaining lymphangioma vessels. Cytokeratin immunolabel; bar = 40 µm.
849
mitted for histologic examination, which yielded a diagnosis of lymphangioma. Lymphangiomas are rare in humans3,4 and hors5–8 es. Lymphangiomas in humans commonly occur as a result of congenital lymphatic malformation and typically develop in the head, axilla, or neck regions, but they can develop in other areas of the body. They usually are benign, do not cause pain, and are soft to semifirm masses, and most are not life-threatening. In humans, 80% of lymphoangiomas are detected by 2 years of age, but acquired lymphangiomas can occur in adults.3,4 Acquired lymphangiomas are usually secondary to trauma, infection, inflammation, or lymphatic obstructions.5 Treatment of choice for lymphangiomas is surgical excision.3,4,6,7 Lymphangiomas can recur after incomplete excision. To the authors’ knowledge, lymphangioma of the equine spermatic cord has not been reported previously, but lymphangioma in the inguinal region in a 3-yearold mare6 and lymphangioma in the pelvic cavity of a colt8 have been reported. Cutaneous lymphangiomas have also been reported in adult horses.5,7 Although rare, lymphangiomas can occur in the scrotum of humans.4 It is not known whether the lymphangioma in the stallion described here was congenital or acquired. Care was taken during surgery to remove all of the abnormal spermatic cord; therefore, the chance of recurrence was judged to be minimal.
Three months after surgery, the owner reported that the stallion did not have any postoperative complications and that the preputial swelling had subsided within a few days after hospital discharge. Semen has not been collected from the stallion since the surgery was performed. Thus, until semen collection and evaluation are performed for the stallion, the authors cannot state unequivocally that the spermatic cord lymphangioma was the cause for the decreased spermatozoa quality. a. b. c. d. e. f.
References 1.
2.
3. 4.
Outcome Six days after the unilateral orchiectomy, the stallion was discharged to the owner. Discharge instructions included daily hand walking or restricted activity in a small paddock for 15 minutes and hydrotherapy with cold water for 10 minutes 2 times/d until the preputial swelling subsided. It was recommended that the stallion be returned to our hospital for another complete breeding soundness examination prior to the 2015 Northern Hemisphere breeding season.
Phantom, Paulsonbilt Ltd, Coatesville, Pa. Nasco, Fort Atkinson, Wis. Aloka 3500, Hitachi Aloka Medical America Inc, Wallingford, Conn. Vicryl, Ethicon Inc, Somerville, NJ. Reimer emasculator, Patterson Veterinary Supply Inc, Devens, Mass. Monocryl, Ethicon Inc, Somerville, NJ.
5. 6. 7. 8.
Schumacher J, Varner DD. Abnormalities of the spermatic cord. In: McKinnon AO, Squires EL, Vaala WE, et al, eds. Equine reproduction. 2nd ed. Chichester, West Sussex, England: WileyBlackwell, 2011;1145–1155. Johnson AK, Love CC. Epididymal abnormalities. In: McKinnon AO, Squires EL, Vaala WE, et al, eds. Equine reproduction. 2nd ed. Chichester, West Sussex, England: Wiley-Blackwell, 2011;1156– 1160. Benson M, Zadvinskis D, Som PM, et al. Embryology and congenital cystic lesions. In: Som PM, Curtin HD, eds. Head and neck imaging. 3rd ed. St Louis: Mosby, 1996;763–769. Lee WC, Park SB, Lee JH, et al. Sonographic findings in a case of scrotal lymphangioma in a 68-year-old male. J Clin Ultrasound 2009;37:428–430. Junginger J, Rotting A, Staszyk C, et al. Identification of equine cutaneous lymphangioma by application of a lymphatic endothelial cell marker. J Comp Pathol 2010;143:57–60. Gehlen H, Wohlsein P. Cutaneous lymphangioma in a young Standardbred mare. Equine Vet J 2000;32:86–88. Hoepp NC, Kim DY, Berent LM, et al. What is your diagnosis? Fluid surrounding a submandibular mass from a horse. Vet Clin Pathol 2013;42:531–532. Turk JR, Gallina AM, Liu IM, et al. Cystic lymphangioma in a colt. J Am Vet Med Assoc 1979;174:1228–1230.
Correction: Comparison of anamnestic responses to rabies vaccination in dogs and cats with current and out-of-date vaccination status In the report “Comparison of anamnestic responses to rabies vaccination in dogs and cats with current and out-of-date vaccination status” (J Am Vet Med Assoc 2015;246:205–211), the name of the individual in footnote a who provided information regarding rabies vaccine formulations is incorrect. The correct individual is Richard Chambers of Zoetis. Also, some clarification is needed regarding the statement in the second paragraph of the section on “Classification of rabies vaccination status” that “A cutoff of 3 years since the last vaccination was used regardless of whether the last vaccine administered had been licensed for a 1-year or 3-year duration, because the antigenic mass, carrier, adjuvant, and other characteristics of 1-year and 3-year vaccines from 2 companies2,a were reportedly identical.” According to Merck Animal Health, although the formulations for their 1-year and 3-year rabies vaccines may be similar, the resultant potencies can differ and one should not assume that the performance of a 1-year vaccine will reliably be equivalent to the performance of a 3-year vaccine. Both vaccines are tested to ensure that they pass USDA-mandated potency requirements. 850
Vet Med Today: Theriogenology Question of the Month
JAVMA, Vol 246, No. 8, April 15, 2015
Theriogenology Question of the Month History A 4-year-old 529-kg (1,164-lb) American Quarter Horse stallion was admitted on January 20, 2014, to the Texas Veterinary Medical Center at the Texas A&M University College of Veterinary Medicine for training to enable semen collection on a breeding dummy, a breeding soundness evaluation, and collection of ejaculates for semen cryopreservation. No abnormalities were noted during physical examination. The stallion displayed good libido toward an ovariectomized teaser mare, readily mounted a breeding dummy,a and ejaculated into a Missouri-model artificial vagina.b Two ejaculates were collected 1 hour apart. Results for the first and second ejaculates, respectively, were as follows: total spermatozoa motility (71% and 75%), progressive spermatozoa motility (56% and 58%), percentage of intact membranes (ie, viability; 64% and 73%), morphologically normal spermatozoa (57% and 81%), and total number of spermatozoa (2.66 X 109 and 3.83 X 109). The second ejaculate was believed to be a better representation of the quality of spermatozoa the stallion was capable of producing at that time. Manual examination of the external reproductive tract was performed following collection of the second ejaculate, and it revealed that the craniolateral portion of the right hemiscrotum was large. This enlargement was identified specifically as the right spermatic cord adjacent to the cranial half of the epididymis. The left hemiscrotum was unremarkable. Ultrasonographicc evaluation of the scrotal contents revealed that the right hemiscrotum contained a large, multiloculated, fluid-filled mass extending from the dorsocranial aspect of the testis along the spermatic cord to the right external inguinal ring. Doppler ultrasonography revealed that blood vessels in the spermatic cord were patent and appeared to be surrounded and compressed by fluid-filled structures (Figure 1). The cranial aspect of the parenchyma of the right testis had a moth-eaten polycystic pattern (ie, mixed echogenic pattern). The body and tail of the right epididymis appeared to be ultrasonographically normal, but the head of the right epididymis could not be identified and appeared to be continuous with the large, multiloculated mass. Volume of the left testis, estimated by use of ultrasonography, was 126.4 mL. Volume of the right testis was not measured. Daily sperm output for the left testis was estimated to be 1.77 X 109 spermatozoa to 2.27 X 109 spermatozoa. Transrectal palpation of the internal reproductive tract revealed that both internal inguinal rings were approximately 4.0 to 4.5 cm in diameter. No other abnormalities were detected. This report was submitted by Jared L. Voge, DVM, MS; John F. Edwards, DVM, PhD; Charles C. Love, DVM, PhD; and Terry L. Blanchard, DVM, MS; from the Departments of Large Animal Clinical Sciences (Voge, Love, Blanchard) and Veterinary Pathobiology (Edwards), College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843. Address correspondence to Dr. Voge ([email protected]). JAVMA, Vol 246, No. 8, April 15, 2015
Figure 1—Doppler ultrasonographic image of a multiloculated, fluid-filled mass compressing the blood vessels within the right spermatic cord of a 4-year-old American Quarter Horse stallion with a large right hemiscrotum. Tick marks at the bottom of the image are at intervals of 1 cm.
Eight additional ejaculates were collected over a period of 4 weeks for semen cryopreservation. The owner subsequently decided to use the stallion for breeding during the 2014 Northern Hemisphere breeding season. The stallion was discharged to the owner with a recommendation to monitor the right hemiscrotum for further enlargement as well as to have semen quality evaluated to detect any changes. Semen was collected multiple times from the stallion after it was discharged from our hospital (data on spermatozoa quality not available). The owner reported that an ejaculate collected at the farm 4 months after discharge from our hospital had no motile spermatozoa. On June 26, 2014 (1 week after collection of the semen sample with no motile spermatozoa), the stallion was readmitted to our hospital. Three ejaculates were collected, which had decreased spermatozoa quality (total spermatozoa motility, 48% to 57%; progressively motile spermatozoa, 38% to 51%; morphologically normal spermatozoa, 28% to 40%). However, total number of spermatozoa in the gel-free portion of the ejaculates (1.37 X 109 to 2.46 X 109) remained similar to results for the initial ejaculates. The moth-eaten appearance of the parenchyma of the right testis now extended over the entire dorsal surface of the testis, and the fluid-filled structures in the right hemiscrotum appeared larger and compressed the left testis. Question What are the most likely differential diagnoses for the enlarged scrotum of this stallion? Please turn the page. Vet Med Today: Theriogenology Question of the Month
847
Answer The list of differential diagnoses should include neoplasia (including mesothelioma), varicocele, spermatic cord torsion, or congenital malformation of the testicular or epididymal tubules. Results Six days after the stallion was readmitted to our hospital, surgery was performed. The stallion prophylactically received broad-spectrum antimicrobials (penicillin G procaine, 22,000 U/kg [10,000 U/lb], IM, once; and gentamicin, 6.6 mg/kg [3 mg/lb], IV, once) and flunixin meglumine (1.1 mg/kg [0.5 mg/lb], IV, q 24 h). Anesthesia was induced, and a right-side, open, unilateral orchiectomy was performed. Preanesthetic sedation and anesthesia were achieved with a combination of xylazine hydrochloride (1 mg/ kg [0.45 mg/lb, IV), diazepam (1 mg/kg, IV), and ketamine hydrochloride (2.2 mg/kg [1 mg/lb], IV). Sevoflurane in oxygen was used to maintain a surgical plane of anesthesia. A ligature of size-2 polyglactin 910d was placed around the cremaster muscle and spermatic cord. The cremaster muscle was transected distal to the ligature. An emasculatore was placed distal to the ligature but proximal to the enlarged spermatic cord. A second ligature of size-2 polyglactin 910 was placed on the spermatic cord proximal to the emasculatore but distal to the first ligature. The emasculator was removed 5 minutes after initial placement, and the spermatic cord was transected distal to the second ligature. Hemostasis was confirmed, and the remaining portion of the cremaster muscle and spermatic cord were placed into the abdomen through the right external inguinal ring. The external inguinal ring was closed with size2 polyglactin 910 in a simple continuous suture pattern. Subcutaneous tissues and the scrotal skin were closed with 2-0 poliglecapronef in a simple continuous suture pattern. After surgery, trimethoprim-sulfadiazine (5 mg of trimethoprim/kg [2.27 mg/lb] and 25 mg of sulfadiazine/kg [11.36 mg/lb], PO, q 24 h) was administered to the stallion. Twenty-four hours after surgery, moderate swelling of the prepuce was detected and treated with daily hand walking (15-minute sessions 3 times/d for 6 days). Administration of flunixin meglumine and trimethoprim-sulfadiazine was discontinued on days 3 and 5 after surgery, respectively. The right testis and spermatic cord were submitted for histologic examination. The right testis and spermatic cord measured 21 X 9.5 X 8 cm (Figure 2). Numerous variably sized, thin-walled, cystic structures filled with pale yellow fluid were located along the spermatic cord, head of the epididymis, and cranial portion of the testis, but they did not obstruct the epididymis. The epididymis appeared to be patent because spermatozoa were detected within the head and tail of the epididymis. The surgical procedure did not result in congestion of the fluid-filled areas; thus, it was assumed the cysts were not dilated veins or arteries. To differentiate lymphatic vessels (ie, endothelium) from testicular ducts, immunohistochemical 848
Vet Med Today: Theriogenology Question of the Month
analysis was performed with the markers factor VIII and cytokeratin. Most of the thin-walled cysts were lined by endothelium (factor VIII antigen-immunoreactive cells; Figure 3), which indicated that they were lymphatic vessels. However, scattered among the numerous lymphatic vessels were smaller, thin-walled, fluid-filled structures lined by a simple, cytokeratinimmunostained epithelium interpreted to be rete mediastinum without spermatids (Figure 4). Tissue containing the large and small fluid-filled cysts compressed the adjacent seminiferous tubules, which had mild degeneration (eg, many of the seminiferous tubules adjacent to the large and small fluid-filled cysts were devoid of germinal cells; Figure 5). Thus, it was presumed that degeneration was a result of compression by the cystic tissue; however, degeneration attributable to thermoregulatory problems could not be ruled out. Neoplasia was not observed. A histopathologic diagnosis of lymphangioma of the spermatic cord with secondary tubular ectasia of the rete mediastinum was made.
Figure 2—Photograph of the cross section of the right testis and spermatic cord of the stallion in Figure 1. Notice the cystic areas dorsal to the head of the epididymis. Bar = 1 cm. JAVMA, Vol 246, No. 8, April 15, 2015
Figure 5—Photomicrograph of lymphangioma cysts (L) with adjacent seminiferous tubules lacking round and elongated spermatids. H&E stain; bar = 500 µm.
Discussion Investigation of scrotal enlargement requires a thorough medical history and complete physical and reproductive examinations that include palpation and ultrasonography. In horses, a clinically normal scrotum has a distinct scrotal neck (ie, dorsal portion of the scrotum), and the testes and attached epididymides should be symmetric and freely movable within the scrotum. The tails of the epididymides should be positioned caudally within the scrotum, with the head and body of each epididymis located dorsolateral to the associated testis. Scrotal enlargement can originate from disease processes involving the scrotal skin, testes, epididymides, spermatic cords, or a combination of these structures or that involve the inguinal canals. In addition, extension of peritoneal processes to the scrotum via the inguinal canal should be considered. Thorough palpation and ultrasonographic evaluation of the scrotal contents should help differentiate the location from which the disease process originates. In the horse described here, the source of the scrotal enlargement (as determined on the basis of initial examination results) appeared to involve the right epididymis or spermatic cord. Disease processes that involve the epididymides or spermatic cords in stallions include inguinal herniation, varicocele, infectious or traumatic funiculitis or epididymitis, spermatic cord torsion, and neoplasia.1,2 The stallion described in the present report did not have a history of inguinal or scrotal injury; therefore, traumatic funiculitis or epididymitis were considered to be unlikely causes of the scrotal enlargement. In cases of acute or subacute infectious epididymitis, stallions usually have recurrent bouts of colic and palpation of the affected epididymis can elicit signs of pain.2 The stallion had no history of colic, the right epididymis was not excessively warm, and palpation of the right epididymis did not elicit signs of pain. Infectious funiculitis was considered unlikely because there were no signs of peritoneal involvement (ie, peritonitis). Inguinal herniation was ruled out because no intestinal loops were ultrasonographically visible in the scrotum or inguinal ring. Spermatic cord torsion, if severe (> 360º), can cause the testis, spermatic cord, and scrotum to enlarge because of venous congestion with resultant necrosis of the dependent testis.1 Spermatic cord torsion was ruled out on the basis of clinical findings and Doppler ultrasonographic detection of blood flow through the spermatic cord. On the basis of the stallion’s history and examination findings and the progressive nature of the lesion, the primary differential diagnoses prior to surgery were neoplasia (particularly mesothelioma), epididymal blockage, or varicocele. A definitive diagnosis could not be determined during the examinations. Because of the owner’s desire to use the stallion during the breeding season, and because the lesion did not appear to be affecting the quality of spermatozoa (which we assumed were produced by the contralateral testis), the owner elected to monitor the stallion’s condition. However, the lesion grew larger and presumably contributed to deterioration of spermatozoa quality; therefore, unilateral orchiectomy was performed. The testis and spermatic cord were sub-
JAVMA, Vol 246, No. 8, April 15, 2015
Vet Med Today: Theriogenology Question of the Month
Figure 3—Photomicrograph of factor VIII antigen–immunolabeled lymphangioma vessels that do not contain erythrocytes. Notice the blood vessel immunoreactive for factor VIII antigen (arrow). Factor VIII antigen immunolabel; bar = 40 µm.
Figure 4—Photomicrograph of cytokeratin-immunolabeled epithelial lining (arrow) of the rete testis that contains several spermatozoa heads surrounded by nonstaining lymphangioma vessels. Cytokeratin immunolabel; bar = 40 µm.
849
mitted for histologic examination, which yielded a diagnosis of lymphangioma. Lymphangiomas are rare in humans3,4 and hors5–8 es. Lymphangiomas in humans commonly occur as a result of congenital lymphatic malformation and typically develop in the head, axilla, or neck regions, but they can develop in other areas of the body. They usually are benign, do not cause pain, and are soft to semifirm masses, and most are not life-threatening. In humans, 80% of lymphoangiomas are detected by 2 years of age, but acquired lymphangiomas can occur in adults.3,4 Acquired lymphangiomas are usually secondary to trauma, infection, inflammation, or lymphatic obstructions.5 Treatment of choice for lymphangiomas is surgical excision.3,4,6,7 Lymphangiomas can recur after incomplete excision. To the authors’ knowledge, lymphangioma of the equine spermatic cord has not been reported previously, but lymphangioma in the inguinal region in a 3-yearold mare6 and lymphangioma in the pelvic cavity of a colt8 have been reported. Cutaneous lymphangiomas have also been reported in adult horses.5,7 Although rare, lymphangiomas can occur in the scrotum of humans.4 It is not known whether the lymphangioma in the stallion described here was congenital or acquired. Care was taken during surgery to remove all of the abnormal spermatic cord; therefore, the chance of recurrence was judged to be minimal.
Three months after surgery, the owner reported that the stallion did not have any postoperative complications and that the preputial swelling had subsided within a few days after hospital discharge. Semen has not been collected from the stallion since the surgery was performed. Thus, until semen collection and evaluation are performed for the stallion, the authors cannot state unequivocally that the spermatic cord lymphangioma was the cause for the decreased spermatozoa quality. a. b. c. d. e. f.
References 1.
2.
3. 4.
Outcome Six days after the unilateral orchiectomy, the stallion was discharged to the owner. Discharge instructions included daily hand walking or restricted activity in a small paddock for 15 minutes and hydrotherapy with cold water for 10 minutes 2 times/d until the preputial swelling subsided. It was recommended that the stallion be returned to our hospital for another complete breeding soundness examination prior to the 2015 Northern Hemisphere breeding season.
Phantom, Paulsonbilt Ltd, Coatesville, Pa. Nasco, Fort Atkinson, Wis. Aloka 3500, Hitachi Aloka Medical America Inc, Wallingford, Conn. Vicryl, Ethicon Inc, Somerville, NJ. Reimer emasculator, Patterson Veterinary Supply Inc, Devens, Mass. Monocryl, Ethicon Inc, Somerville, NJ.
5. 6. 7. 8.
Schumacher J, Varner DD. Abnormalities of the spermatic cord. In: McKinnon AO, Squires EL, Vaala WE, et al, eds. Equine reproduction. 2nd ed. Chichester, West Sussex, England: WileyBlackwell, 2011;1145–1155. Johnson AK, Love CC. Epididymal abnormalities. In: McKinnon AO, Squires EL, Vaala WE, et al, eds. Equine reproduction. 2nd ed. Chichester, West Sussex, England: Wiley-Blackwell, 2011;1156– 1160. Benson M, Zadvinskis D, Som PM, et al. Embryology and congenital cystic lesions. In: Som PM, Curtin HD, eds. Head and neck imaging. 3rd ed. St Louis: Mosby, 1996;763–769. Lee WC, Park SB, Lee JH, et al. Sonographic findings in a case of scrotal lymphangioma in a 68-year-old male. J Clin Ultrasound 2009;37:428–430. Junginger J, Rotting A, Staszyk C, et al. Identification of equine cutaneous lymphangioma by application of a lymphatic endothelial cell marker. J Comp Pathol 2010;143:57–60. Gehlen H, Wohlsein P. Cutaneous lymphangioma in a young Standardbred mare. Equine Vet J 2000;32:86–88. Hoepp NC, Kim DY, Berent LM, et al. What is your diagnosis? Fluid surrounding a submandibular mass from a horse. Vet Clin Pathol 2013;42:531–532. Turk JR, Gallina AM, Liu IM, et al. Cystic lymphangioma in a colt. J Am Vet Med Assoc 1979;174:1228–1230.
Correction: Comparison of anamnestic responses to rabies vaccination in dogs and cats with current and out-of-date vaccination status In the report “Comparison of anamnestic responses to rabies vaccination in dogs and cats with current and out-of-date vaccination status” (J Am Vet Med Assoc 2015;246:205–211), the name of the individual in footnote a who provided information regarding rabies vaccine formulations is incorrect. The correct individual is Richard Chambers of Zoetis. Also, some clarification is needed regarding the statement in the second paragraph of the section on “Classification of rabies vaccination status” that “A cutoff of 3 years since the last vaccination was used regardless of whether the last vaccine administered had been licensed for a 1-year or 3-year duration, because the antigenic mass, carrier, adjuvant, and other characteristics of 1-year and 3-year vaccines from 2 companies2,a were reportedly identical.” According to Merck Animal Health, although the formulations for their 1-year and 3-year rabies vaccines may be similar, the resultant potencies can differ and one should not assume that the performance of a 1-year vaccine will reliably be equivalent to the performance of a 3-year vaccine. Both vaccines are tested to ensure that they pass USDA-mandated potency requirements. 850
Vet Med Today: Theriogenology Question of the Month
JAVMA, Vol 246, No. 8, April 15, 2015
