Coccidioides immitis Encephalitis in Two Dogs

SUMMARY Two adult dogs were purchased in southern Arizona for use in institutional research. Both dogs were normal during a quarantine and standardization period and were subsequently assigned to specific projects. Twelve months (dog 1) and 9 months (dog 2) after purchase, the dogs developed signs of central nervous system disease; one dog had tetanic seizures, incoordination, and coma; the other, epileptiform seizures and limb spasms. Both dogs were euthanatized. Histologic examination of dog 1 revealed numerous granulomas in the cerebrum, midbrain, lungs, heart, testicles, liver, and kidneys. The second dog had granulomas only of the cerebrum. In both cases many of the granulomas contained periodic acid-Schiff (pas)-positive refractile organisms. Coccidioides immitis infection was diagnosed in each case on the basis of microscopic findings.