Signalment:  

Tissues are from a 4-year-old, intact male Poodle dog (Canis familiaris)Kennel History:
Patient History:
Infertility. Small soft testicles with firm epididymis bilateral. Left testicle had a fluid filled lesion on ultrasound. Prostate enlarged, fluctuant and painful, straining to defecate and blood in stool. Mild conjunctivitis.


Gross Description:  

Significant findings were restricted to the genital system. The prostate gland is mildly enlarged, but symmetrical. The testicles are atrophied and soft. They are slightly yellow-tan colored and lack normal lobular appearance. The right testicle contains a central, 0.5cm area of cavitation containing exudates or sequestered necrotic tissue. The epididymis (bilateral) is slightly firm, but no gross lesions are noted when incised.


Histopathologic Description:


Testicles: There is diffuse, severe atrophy of the seminiferous tubules. In several areas, there are small clusters of remaining tubules that are small, hypocellular and have thickened hyalinized basement membranes. There is no evidence of spermatogenesis. Conspicuous clusters of interstitial cells are present within the testicle. There is diffuse lymphohistiocytic infiltration throughout the parenchyma. In addition, there is one cavity containing ischemic necrotic tissue sequestrum surrounded by dense lymphohistiocytic infiltrates. 

Epididymis: The lesions are similar to those in the testicle with diffuse, dense sheets of lymphohistiocytic cells, atrophic tubules, inflammatory cell infiltrates in tubular walls, plus intense lymphohistiocytic clusters within tubules (Fig. 3-1). There are no spermatids in epididymal tubules. 

Prostate gland: The majority of the prostate gland examined is composed of hyperplastic acini lined with a single layer of tall, plump columnar epithelium with abundant eosinophilic cytoplasm. An occasional small lymphoid nodule is present within the interstitium of these areas. Within one lobe, there is marked acinar atrophy with reduction in the number of acini and diffuse, dense sheets of lymphocytes, plasma cells and macrophages. The remaining acinar walls are moderately infiltrated with primarily lymphocytes. 
*** Sections submitted will contain either testicle, testicle and epididymis, or prostate gland.


Morphologic Diagnosis:  


Testicles: Orchitis, lymphohistiocytic, chronic, severe, diffuse with marked seminiferous tubular atrophy and focal necrosis (Fig. 3-2)
Epididymis: Epididymitis, lymphohistiocytic, chronic, severe


Lab Results:  

Bacteriology Results; Aerobic Culture; Tissue: Testicle; Organism ID: Brucella canis


Condition:  

Brucella canis


Contributor Comment:  

This case represents one of several dogs seen from the same kennel with a history of infertility. Most of the patients either tested positive for Brucella canis by agar gel immunodiffusion or yielded positive bacterial cultures from either epididymis/testes, lymph nodes or prostate glands. In the male reproductive system, the classic appearance of canine brucellosis is a severe epididymitis that is accompanied by varying degrees of testicular atrophy. Inflammation of the testicles (orchitis) is infrequently seen. Therefore, the unique feature of this case is the level of inflammation/destruction in the testicle. When orchitis occurs secondary to B. canis, it can be severe and characterized by primarily lymphoplasmacytic infiltrates with destruction of seminiferous tubules and occasional foci of necrosis.(1,3) Inflammation can extend into the vaginal tunic with draining ulcers from the scrotum.(3)

Brucellosis in dogs has been described with B. melitensis, B. suis, B. abortus and B. canis; however, only B. canis is considered epidemiologically significant.(4) B. canis has been reportedly recovered from just about every bodily fluid and/or surface: vaginal secretions, semen, abortuses, milk, urine, saliva, ocular secretions and feces.(4) The organism is transmitted through venereal and/or oral routes. Following entry, the organism is taken up by the mononuclear-phagocytic system and distributed to the lymphoid and genital compartment where the organisms multiply.(4) Bacteremia develops and proliferation of the organism in the target organs results in the lesions typical of the disease: uterine infection and abortion in females, epididymitis and prostatitis in males, lymphadenitis, discospondylitis, anterior uveitis, dermatitis, meningoencephalitis (refer to nice flow chart, pg. 197 of Ref. #4). Diagnosis is achieved through serology, agglutination tests, agar gel immunodiffusion, ELISA, and immunofluorescence; however, definitive diagnosis can only be made through retrieval of the organism from bacterial culture.(4) Treatment is difficult, in part because of the intracellular nature of the organism. Many different drugs and drug combinations have been tried, but no combination has been found to be 100% effective.(4) Combination drug treatments have shown better efficacy than single antibiotic therapies.(4) Lastly, B. canis has zoonotic potential. The incidence of human infections is not known.(4) People contract the disease through contact with the organism shed during abortions or in research laboratories where people work directly with the organism.(4)


JPC Diagnosis:  


1. Testicle: Orchitis, lymphohistiocytic, chronic, diffuse, severe, with marked seminiferous tubular atrophy and loss, and interstitial cell hyperplasia
2. Epididymis: Epididymitis, lymphohistiocytic, chronic, diffuse, severe
3. Epididymis: Epithelial hyperplasia, diffuse, marked


Conference Comment:  

Considerable time was spent discussing the changes within the interstitial cell population (Fig. 3-3). Dr. Schlafer and the attendees discussed the proliferation of interstitial cells and debated hyperplasia versus neoplasia. The contributor mentioned a conspicuous cluster of interstitial cells when describing the proliferation, and at the end of the conference considerable disagreement still existed as to whether this change represented interstitial cell hyperplasia or an interstitial cell tumor.

Abortions caused by B. canis are normally late gestational abortions that occur after 50 days. As seen in this case, the usual sequelae to B. canis infection in male dogs is epididymitis and testicular degeneration. This often causes severe scrotal irritation and affected dogs often focus on this discomfort and lick the area until it is ulcerated. Lymphadenopathy of the mandibular and retropharyngeal lymph nodes is common. Placental lesions consist of necrosis of chorionic villi with a plethora of bacteria within infected trophoblastic cells. Infected females often discharge copious amounts of foul vaginal secretions after abortion, which is an excellent means of disease transmission. Fetal lesions are fatal and include pneumonia, endocarditis, and hepatitis.(2)

Brucella canis is caused by a mucoid strain of Brucella that is similar to Brucella suis. Because of its mucoid nature, B. canis lacks surface antigens that B. abortus and B. melitensis have, thus rendering conventional test methods ineffective.(2)


References:

1. Gleiser CA, Sheldon WG, VanHoosier GL, Hill WA. Pathologic changes in dogs infected with a Brucella organism. Lab Anim Sci. 21:540-545, 1971
2. Schlafer DH, Miller RB: Female genital system. In: Jubb, Kennedy, and Palmer's Pathology of Domestic Animals, ed. Maxie MG, vol. 3, pp. 484-489. Elsevier Limited, Philadelphia, PA, 2007
3. Schoeb TR, Morton B: Scrotal and testicular changes in canine brucellosis: a case report. J Am Vet Med Assoc. 172:598-600, 1978
4. Wanke, MM: Canine brucellosis. Anim Reprod Sci. 82-83:195-207, 2004


Click the slide to view.


3-1. Epididymis, dog


3-2. Testicle, dog.


3-3. Testicle, dog


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