Challenges in diagnosing respiratory capillarioses in dogs and cats

Respiratory capillarioses is caused by Capillaria aerophila, which leads to pulmonary infections in dogs and cats, and Capillaria boehmi, which results in nasal infections in dogs, are emerging yet underdiagnosed parasitic diseases. Capillarioses may be subclinical or manifest with different respiratory and non-specific clinical signs. Occasionally, neurological signs may occur in dogs infected with C. boehmi. A clinical diagnosis is not possible because of the lack of specificity of clinical signs. The parasitological diagnosis can be complicated by the microscopic similarities between the eggs of C. aerophila and C. boehmi, those of non-respiratory or pseudoparasitic Capillaria spp. and those of Trichuris spp., especially in mixed infections. Additionally, co-infections may complicate the clinical picture, hindering the aetiological diagnosis. This article describes the main practical features of respiratory capillarioses of dogs and cats, focusing on the challenges in the diagnostic approach. The appropriate application of different diagnostic tools is discussed.