A case of suspected vertical hepatozoonosis manifesting as severe anemia and gastroenteritis in a three-month-old puppy following vaccination.

purposeThis case report describes the diagnosis of Hepatozoon canis in a 3-month-old male mixed-breed puppy with acute symptoms of lethargy, mucous membrane pallor, and severe gastrointestinal symptoms. The symptoms developed after routine vaccination.

methodsA thorough clinical history was obtained, followed by a complete physical examination and hematological analysis. Blood smears were prepared, stained with Giemsa, and examined microscopically. Molecular confirmation of infection was performed via polymerase chain reaction (PCR) targeting the 18 S rRNA gene.

resultsHematological analysis showed normocytic normochromic anemia, thrombocytopenia, and a slight left shift. Microscopic examination of blood smears revealed multiple Hepatozoon gamonts in neutrophils, and molecular diagnosis was performed by PCR targeting the 18 S rRNA gene, which confirmed H. canis infection.

conclusionGiven the young age of the puppy, the lack of a possible history of exposure to ticks, and the observance of preventive care, vertical transmission from mother to fetus was likely. The acute onset of illness shortly after vaccination may indicate immune stress from the polyvalent vaccine and subsequent activation of a latent infection. This report suggests that H. canis should be considered as a possible diagnosis in young puppies presenting with severe gastrointestinal symptoms. The importance of vertical transmission and the role of immunological stressors, such as vaccination, in the emergence of acute disease from a dormant infection should be considered.