Myxomatosis

 

Myxomatosis is caused by the myxoma virus, a poxvirus specific for rabbits.

It is transmitted by mosquitoes, biting flies and direct contact. Several strains are pathogenic.

Symptoms

The first characteristic sign is conjunctivitis that rapidly becomes more marked and accompanied by a milky discharge from the inflamed eyes. The animal is listless and anorectic, and the temperature frequently reaches 42° C. In acute outbreaks, some animals may die within 48 hours after showing signs. Those that survive become progressively depressed, develop a rough coat, and the eyelids, nose, lips, and ears become oedematous, giving a swollen appearance to the head. The vent becomes inflamed and oedematous, and in the male, the scrotum swells. A characteristic sign at this stage is drooping of the oedematous ears. A purulent nasal discharge invariably appears, breathing becomes labored, and the animal goes into a coma just before death, which usually occurs within 1-2 weeks after the appearance of clinical signs.


Diagnosis

Few characteristic lesions are found at necropsy. The spleen is occasionally enlarged and is almost always devoid of lymphocytes when examined histologically. The seasonal incidence of the disease, the clinical appearance of infected animals, and the high mortality are all of diagnostic significance. Large eosinophilic cytoplasmic inclusion bodies in the conjunctival epithelial cells are also helpful.


Treatment

There is no effective treatment.

Prophylactic vaccination is possible.