Pancitopenia induzida em um cão pelo uso concomitante de fármacos mielotóxicos / Pancytopenia in a dog induced by concomitant use of myelotoxic drugs

ABSTRACT

Background: The indiscriminate use of drugs is an issue in Veterinary Medicine, as it has serious consequences for theanimals. Many drugs are myelotoxic and cause a decrease in the production of blood cells, which may be irreversible insome cases. The present work reports a case of pancytopenia induced by the concomitant use of myelotoxic drugs (estrogen, metamizole and phenobarbital) in a dog and describes findings on myelotoxicity, hematological alterations andtreatment success.Case A 7-year-old Lhasa Apso bitch was referred to the Veterinary Hospital of Federal University of Paraná, Curitibacampus, with hematuria and a history of treatment with phenobarbital [2 mg/kg twice a day (bis in die, BID)], metamizole[25 mg/kg 3 times a day (ter in die, TID)], and use of estrogen hormone (estradiol cypionate). At physical examination, theanimal was normohydrated and exhibited normal palpable lymph nodes, pale mucous membranes, galactorrhea, and a bodytemperature of 36°C. A complete blood count including reticulocyte count and a total plasma protein (TPP) exam wererequested. The results revealed pancytopenia (18% hematocrit, 1,400 total leucocytes/µL, and 22,000 reticulocytes/µL).An abdominal ultrasound exam did not detect any relevant alterations. In view of the results obtained, medullary aplasiawas suspected. A bone marrow aspiration was performed. A myelogram revealed a decrease in cellularity (erythrocyticand granulocytic hypoplasia), with presence of rare erythroid and granulocytic precursors. The diagnosis was medullaryaplasia. The animal was treated, and the evolution of the hematological alterations was monitored. The treatment consistedof administration of erythropoietin (100UI/kg subcutaneously every 48 h), prednisone (2 mg/kg BID), Leucogen (3 mg/kg BID), interferon (0.2 IU/kg BID) and Eritrós Dog Tabs [1 tablet once a day (semel in die, SID)]. After 5 days of treatment, the...