Orchitis

Inflammation of the testes can be caused by many bacteria and viruses. The inflammation is often followed by destruction of sperm-producing capacity of the infected testis. In dogs, orchitis is a common disease and is generally accompanied by epididymitis (inflammation of an oblong structure at the side of the testicle consisting of a tightly coiled tube connected to sperm tubes).

Bacterial Orchitis

In bacterial orchitis, the most common route of infection is via reflux from the bladder. In these cases, E.coli and Proteus vulgaris are the most commonly isolated organisms. Brucella canis bacteria that causes brucellosis can cause a severe orchitis in dogs.

Lymphocytic Orchitis

Lymphocytic orchitis is caused by failure of the animal's immune system to recognize the testis as "self" and it results from and autoimmune reaction. Eventual destruction of the testis usually follows. The immunologic attack is often triggered following testicular trauma, infection or inflammation in dogs with a genetic predisposition. The primary clinical sign is infertility and lack of sperm in the semen when both testes are involved. Because of the progressive nature of this condition, the prognosis for return of fertility is poor.

Signs of Orchitis

Clinical signs include sudden pain, scrotal swelling, lethargy, and reluctance to stand or walk. Such dogs should be examined by a veterinarian immediately. Because of the pain, dogs often resist physical examination.

Treatment of Orchitis

Complete resolution or cure of orchitis is rare without removal of the affected tissue. Bilateral orchiectomy is the recommended treatment. Unilateral castration, sparing the unaffected testis, may be the only hope of retaining fertility in affected male dogs that have great breeding value, but is not usually recommended. Antimicrobial drugs alone are rarely effective in dogs but are often included in the treatment regimen.

Prognosis for Orchitis

Prognosis is good for dogs not infected with Brucella canis that undergo bilateral orchiectomy.

References:
1. Clinicopathologic Principles for Veterinary Medicine By Wayne F. Robinson, Clive R. R.
2. Small animal theriogenology By Margaret V. Root Kustritz
3. UC Davis Book of Dogs By Mordecai Siegal, Jeffrey E. Barlough, University of California, Davis