This page is part of the Veterinary Reproductive Pathology site and is dedicated to disease of the epididymis and deferent duct of the bull
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| Disease of the Epididymis Disease of the Deferent Duct |
The most important diseases of the epididymis of all species are involve inflammation. Infectious epididymitis is the most important but unlike the ram, is not well studied. One very important and often missed disease is spermatic granuloma of the epididymal head. This is an inflammatory (granulomatous inflammation to spermatozoa) disease with an anomalous and potentially genetic basis.
The presence of spermatozoa, which are antigenic and which also induces a foreign body type disease, within the lumen of the epididymal duct complicates the responses of this organ to injury. Spermatozoa induce a foreign body and immune mediated response and the character is typically granulomatous. Spermatozoa are continuously produced and move through the duct. Any obstruction of the duct of the epididymis results in increased pressure and the likelihood of rupture. A rupture or perforation of the tube will eventually lead to the formation of a cavity containing impacted spermatozoa. In severe cases, the spermatozoa will be released into the cavity surrounded by the vaginal tunics.
Spermatic granulomas thus formed develop anywhere that spermatozoa are found. Most cases occur because of
- blind efferent ductules
- abberent epididymal ducts
- adenomyosis of the epididymis
- infectious epididymitis (seen in dogs).
Viral causes of epididymitis are rare. Bulls in Kenya and South Africa developed a specific infectious epididymitis, called epididymitis-vaginitis (“epivag”). Lesions consist initially of soft swelling of the epididymis with subsequent enlargement and fibrosis. Other lesions include “abscess” formation, tunic adhesions, ampullitis, vesicular adenitis, and testicular degeneration. Sometimes, however, the vesicular glands only are affected. Bovine herpesvirus 4 is implicated in the disease.
Epididymitis in calves
Dobberstein (2020) reported on a 2 month old calf that had scrotal swelling and chronic epididymitis
Dobberstein R. Isolation of Histophilus somni and Trueperella pyogenes from a 2-month-old calf with chronic fibrosing and suppurative epididymitis. Can Vet J. 2020 Jul;61(7):776-778. PMID: 32655163; PMCID: PMC7313357.
Epididymitis in adults
Bacterial infection of the epididymis usually occurs via two main routes, ascending infection from the urethra via the deferent duct and accessory genital glands, or hematogenous spread. Descending infection from the testis, and direct penetrating injury are both theoretically possible, but much less likely.
Brucella abortus rarely causes epididymitis in the absence of orchitis.
Actinobacillus seminis, a frequent cause of epididymitis in rams, has been isolated from the semen of a bull with bilateral epididymitis.
Epididymitis is observed in bulls with vesicular adenitis induced by inoculation of Mycoplasma bovigenitalium, but the role of mycoplasmas and chlamydias in causing epididymitis await clarification.
Epididymitis may accompany orchitis, periorchitis, and testicular degeneration in cattle, horses, sheep, goats, and dogs infected with Trypanosoma brucei.
Spermatic granuloma of the epididymal head (SGEH)
As this is a congenital anomaly, it is discussed in Disorders of Sexual Development of bulls
Development of the epididymis parallels that of the testis, and in particular, the passage of spermatozoa. A small and hypoplastic epididymis occurs with concurrent testicular hypoplasia, or with obstruction to the flow of fluid (and spermatozoa) from the testis such as with segmental aplasia of the epididymis (upstream of the hypoplastic segment) or with spermatic granuloma of the epididymal head
Adenomyosis is when there is an outpouching of the epitheliium of the epididymis into the smooth muscle layer. This cavity can be a site of spermiostasis and subsequent spermatic granuloma formation. It can be induced by exposure to estrogens.
Neoplasms of the epididymis is extremely rare!
Epithelial neoplasms
Stromal neoplasms
Round cell neoplasmsLymphoma of the epididymis is reported
As this is a developmental/congenital condition because of blind ending efferent ductules, it is discussed in Disorders of Sexual Development in bulls