Sporotrichosis Outburst after Cancer Chemotherapy in a Dog

Abstract

Background: Sporotrichosis is a dermatozoonosis that affects mammals in general, with the domestic feline (Felis catus) being the most epidemiologically important species. However, diagnosis of this disease in dogs is important considering the proximity with people and with other communicants. The epidemiology of sporotrichosis is already known in some states of Brazil, especially in the southeast region, but to the best of our knowledge there are no reports of sporotrichosis in non-human species in the state of Espírito Santo. This paper aimed at describing the first case of canine sporotrichosis in Espírito Santo, Brazil.Case: A 10 year-old Bull Terrier male dog was presented with nodular non-ulcerated lesions on the head and nodular ulcerated lesion on the nasal planum. The dog had a previous diagnosis of a low-grade mast cell tumour and palpebral melanoma. Mast cell tumour was treated with scrotum ablation (and orchiectomy) and bilateral inguinal lymph node removal, followed by chemotherapy with twelve intravenous infusion of vinblastine, along with prednisolone. Cutaneous lesions in the head and nasal planum appeared two months after finishing chemotherapy. At further anamnesis, the pet´s responsible reported that the dog had the habit of hunting cats that entered the residence, which raised the hypothesis of sporotrichosis. An undiagnostic cytology was performed, followed by a fungal culture, positive for Sporothrix schenckii. Treatment was then initiated with itraconazol (Oficial generic drug), at a dose of 10mg/kg/SID, until clinical remission, obtained after 60 days, maintaining it for 60 more days. Patient showed completed recovery, with no further complatints after a follow-up of more than 220 days.Discussion: Sporotrichosis is considered a rare disease in dogs, with isolated cases in the literature. The dog of the present report was diagnosed with sporotrichosis two months after the end of a chemotherapy treatment for a mast cell tumour. Therefore, it is suggested that the patient in this study was infected during an immunosuppressive phase. The same can occur with other immunosuppressive treatments, such as glucocorticoid, also included in the chemotherapy treatment of this patient, calcineurin inhibitors (cyclosporine) and mercaptopurine derivatives (azathioprine). Cytology is usually unconclusive for such lesions in dogs, once only a few yeast might be present. Nevertheless, the definitive diagnosis was obtained through fungal microculture. Treatment with itraconazol was successful but dogs might also present favorable responses to ioidine. Itraconazole is a fungistatic drug, fungicidal only in high doses. For this reason, if the fungistatic dose is not administered for sufficient time, recurrences may occur. In the last three years, Espirito Santo has become a new epidemiological scenario for sporotrichosis, and it is placed in the route of transmission, closely to Rio de Janeiro. Cats are the most affected animals and are commonly responsible for transmission to other species, including humans. The increase in cases of canine sporotrichosis requires its inclusion in the differential diagnosis of nodular-ulcerative lesions, along with cutaneous neoplasias and immune-mediated diseases.