Morphological and molecular identification of Acanthocheilonema reconditum in a canine

Acanthocheilonema reconditum (A. reconditum) is a nematode with low pathogenicity that causes canine filariasis, without clinical signs. This filarid produces microfilariae that circulate in the blood of their natural hosts. Microfilariae of A. reconditum can be easily confused with microfilariae of Dirofilaria immitis (D. immitis) which causes a severe disease in dogs. The aim of this article is to describe a case of A. reconditum infection in a dog, diagnosed by fine needle aspiration cytology (FNAC) of two cutaneous nodules, blood smear examination, and further confirmed by molecular assay (PCR). This report alerts veterinarians to the presence of A. reconditum in the region of Santa Maria, Rio Grande do Sul, Brazil, and highlights the importance of performing the differentiation of microfilaria species. In addition, it demonstrates the importance of fine needle aspiration cytology as a diagnostic tool.