Retrospective case-control study of hepatozoonosis in dogs in Israel.

Signalment, clinical signs, and physical examination and clinicopathologic findings in dogs diagnosed with Hepatozoon canis parasitemia (n = 100) were compared with those in Hepatozoon-negative dogs (n = 180). A subset (n = 15) of Hepatozoon-positive dogs with unusually high (> 800 H canis gametocytes/microL of whole blood) parasitemia was compared with dogs that had low parasitemia (n = 85) and with Hepatozoon-negative dogs (n = 180). Hepatozoon-positive dogs significantly differed from Hepatozoon-negative dogs in body temperature, total red blood cell count, hemoglobin concentration, hematocrit, and platelet count. Dogs with high H canis parasitemia significantly differed from those with low parasitemia in hemoglobin concentration, hematocrit, and total neutrophil count. Clinical findings from dogs with high H canis parasitemia included emaciation, lethargy, hyperglobulinemia, hypoalbuminemia, and increased serum alkaline phosphatase and creatine kinase activities. Findings at necropsy included hepatitis, pneumonia, and glomerulonephritis associated with H canis schizonts and extensive parasitism of bone marrow, spleen, and lymph nodes. Low hemoglobin concentration, low platelet count, and concurrent parvovirus infection together represented the best predictor variables for Hepatozoon positivity in dogs presenting to the hospital.