Use of a Cytobrush for Sampling the Ear Canal of Dogs With Otitis Externa

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.

To compare the cytobrush as a sampling tool for the ear canal of dogs with OE and compare it with the swab technique.

Thirty ears from 17 dogs with OE, presented at a veterinary teaching hospital, were included for sampling.

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.

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.

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.