Comparing cytobrush and swab for sampling dog ear infections

Abstract

BACKGROUND: Cytological examination of the ear canal is essential for evaluating dogs with otitis externa (OE). The conventional sampling method uses a swab. However, the cytobrush (gynaecological cervical brush), already used for cytological collection from other anatomical sites, has not been adequately investigated for this purpose in dogs with OE. OBJECTIVES: To compare the cytobrush as a sampling tool for the ear canal of dogs with OE and compare it with the swab technique. ANIMALS: Thirty ears from 17 dogs with OE, presented at a veterinary teaching hospital, were included for sampling. MATERIALS AND METHODS: Cytological samples were collected using both a cytobrush and a swab in random order. Two independent and blinded evaluators quantified micro-organisms (cocci, bacilli, yeasts), mononuclear cells, polymorphonuclear cells and epithelial cells. Animal discomfort during sampling was assessed using a scoring system. RESULTS: No significant differences were found between the methods regarding the presence of micro-organisms or inflammatory and epithelial cells (p > 0.05), indicating equivalence between techniques. The intraclass correlation coefficient (ICC > 0.9) demonstrated high reproducibility between evaluators. Although the oto-podal reflex was more frequent with the cytobrush, it did not significantly impact overall animal discomfort. CONCLUSIONS AND CLINICAL RELEVANCE: The cytobrush is an effective, safe and well-tolerated sampling method, and may be considered a viable alternative to the swab for collecting samples from the ear canal of dogs with OE.