Characterisation of Liver Pathology in Dogs with Canine Hepatozoonosis in Calabar, Cross River State

Canine hepatozoonosis caused by Hepatozoon canis is a tick-transmitted protozoan infection increasingly recognised as a cause of debilitating disease in domestic dogs in the South South geopolitical zone of Nigeria. This study characterised the haematological and histopathological features of hepatozoonosis in dogs attending veterinary clinics in Calabar, Cross River State, from February to October 2023. Thirty-eight dogs with clinical signs of fever, weight loss, reluctance to move, and generalised weakness were recruited. Peripheral blood smears stained with Giemsa were examined for gamonts within neutrophils and monocytes. Tissue samples from the liver, spleen, skeletal muscle, and bone marrow were collected during necropsy of eight animals that died and processed histologically. Peripheral blood examination confirmed Hepatozoon canis gamonts in neutrophils in 94.7 percent of cases. Haematological findings included lymphopaenia, neutrophilia, and anaemia. Histopathologically, meronts and macro-gamonts were identified in hepatic and splenic parenchyma within mononuclear phagocytic cells. Periportal lymphoplasmacytic hepatitis and splenic lymphoid hyperplasia were the predominant lesions. Myositis with intramuscular cyst formation was observed in skeletal muscle. These findings are consistent with current documentation of H. canis pathology in tropical West Africa. Improved tick control, owner awareness, and access to anti-parasitic treatment are essential management strategies. Keywords: Hepatozoon canis, hepatozoonosis, histopathology, dogs, Calabar