HEPATOZOONOSIS IN DOGS - 22 CASES (1989-1994)

Objective-To document hepatozoonosis in dogs from Alabama and Georgia and to report associated clinical signs, method of diagnosis, response to treatment, and course of disease. Design-Retrospective case series . Animals-22 dogs in which Hepatozoon canis was identified by microsco pic examination of skeletal muscle. Procedure-We reviewed medical reco rds of all dogs with a definitive diagnosis of hepatozoonosis that wer e referred to the Auburn University Small Animal Clinic between 1989 a nd 1994. Results-Diagnoses were confirmed by microscopic identificatio n of H canis schizont or merozoite stages in skeletal muscle. The game tocyte stage was not detected in smears of blood obtained from a perip heral vein, buffy-coat smears, or bone marrow evaluation. Common clini cal signs included fever, cachexia, ocular discharge, pain, stiffness, and paresis. Laboratory abnormalities included marked leukocytosis, h ypoglycemia, hypoalbuminemia, mild anemia, hyperphosphatemia, and high alkaline phosphatase activity. Periosteal bone proliferation was evid ent radiographically in 18 of 22 dogs. Renal lesions included amyloido sis (1 dog), interstitial nephritis (3), and mesangioproliferative glo merulonephritis (4). Treatment with the anticoccidial drug toltrazuril , despite an initial favorable response, failed to prevent relapse in all but 3 of 21 treated dogs. Mean survival time was 12.6 +/- 2.2 mont hs, with a mean time of remission before recurrence of clinical signs of 6 months. Clinical Implications-H canis infection in dogs can be as sociated with a distinct clinical syndrome that involves chronic myosi tis, debilitation, and death. The dogs of this report represent the fi rst substantial number of domestic dogs naturally infected with H cani s in the United Stares outside of the Texas Gulf Coast. Hepatozoon can is appears to be a serious pathogen in the United States that is becom ing more widespread geographically.