Ocular and encephalic toxoplasmosis in canaries

In this report we describe the lesions produced by the protozoal organism, Toxoplasma gondii, in the eyes and brain of the common yellow canary (Serin us canaria). Nine of 15 birds in a flock were affected with blindness, whic h developed over a 3-mo span, and two birds developed torticollis. Microsco pic alterations within the eye consisted of a nonsuppurative chorioretiniti s with large numbers of macrophages that contained the tachyzoite form of T . gondii in the subretinal space, and aggregates of tachyzoites were found in the nerve fiber layer of the retina with and without necrosis. Tissue cy sts with bradyzoites were scattered throughout the meninges and neuropil of the cerebrum and cerebellum. Both forms were confirmed by transmission ele ctron microscopy in the eye and brain. Frozen brain samples reacted with T: gondii-specific cat sera in indirect fluorescent antibody tests. The source of infection was hypothesized to be from a stray cat the owner kept chat h ad access to some of the bird feed. Treatment (trimethoprim 0.08 g/ml H2O a nd sulfadiazine 0.04 g/ml in water for 2 wk) was instituted by the referrin g veterinarian on the remaining birds. A second treatment regime was given for 3 wk. The owner of the canaries did not return for further treatment.