PCR amplification and DNA sequencing of D emodex injai from otic secretions of a dog

Background The identification of D emodex mites from dogs is usually based on morphology and location. Mites with uncharacteristic features or from unusual locations, hosts or disease manifestations could represent new species not previously described; however, this is difficult to determine based on morphology alone. Hypothesis/Objectives The goal of this study was to identify and confirm D emodex injai in association with otitis externa in a dog using PCR amplification and DNA sequencing. Methods Otic samples were obtained from a beagle in which a long‐bodied D emodex mite was identified. For comparison, D emodex mite samples were collected from a swab and scraping of the dorsal skin of a wire‐haired fox terrier and an otic sample from a dog with generalized and otic demodicosis. To identify the D emodex mite, DNA was extracted, and 16S r RNA was amplified by PCR , sequenced and compared with D emodex sequences available in public databases and from separate samples morphologically diagnosed as D . injai and D emodex canis . Results PCR amplification of the long‐bodied mite r RNA DNA obtained from otic samples was approximately 330 bp and was identical to that from the mite morphologically identified as D . injai obtained from the dorsal skin of a dog. Furthermore, the examined mite did not have any significant homology to any of the reported genes from D emodex spp. Conclusions These results confirmed that the demodex mites in this case were D . injai .