2025 - CO-INFECTION BY CANINE TRANSMISSIBLE VENEREAL TUMOR, HEPATOZOONOSIS, AND DIROFILARIASIS – A CLINICAL CHALLENGE IN DOGS – CASE REPORT

Canine transmissible venereal tumor (CTVT) is a round cell neoplasm of mesenchymal origin that is primarily transmitted through the coitus, affecting the genital mucosa of dogs. This study describes a case of co-infection with CTVT, canine hepatozoonosis, and dirofilariasis in a mixed-breed, intact male dog from the metropolitan region of Grande Vitória, Espírito Santo, Brazil. The patient presented with persistent penile bleeding and, after complementary examinations, was diagnosed with CTVT through fine-needle aspiration cytology, hepatozoonosis via blood smear, and dirofilariasis using the SNAP 4Dx® Plus test, which also revealed co-infection with Ehrlichia canis and Anaplasma spp. The therapeutic approaches included vincristine sulfate chemotherapy for CTVT, imidocarb dipropionate for hepatozoonosis, doxycycline for ehrlichiosis and anaplasmosis, and ivermectin for dirofilariasis. This case highlights the clinical challenge of managing co-infections in immunosuppressed patients due to chemotherapy, which facilitates the manifestation of opportunistic infections such as hepatozoonosis. The use of complementary diagnostic methods and continuous hematological monitoring is crucial for successful treatment. This report emphasizes the importance of an integrated clinical approach for diagnosing and managing co-infections, especially in regions endemic to vector-borne diseases, to optimize patient prognosis and quality of life.