Diagnostic value of cytological analysis of tumours and tumour-like lesions of the oral cavity in dogs and cats: A prospective study on 114 cases

•Cytology was compared to histopathology for the diagnosis of masses of the oral cavity of dogs and cats.•FNI in dogs showed the highest sensitivity and specificity for oral tumours.•In cats all methods had high sensitivity and specificity for oral lesions.•Cytology is appropriate to correctly diagnose lesions of the oral cavity in dogs and cats.

Neoplastic or non-neoplastic masses are common findings in the oral cavity of cats and dogs. The aim of this prospective study was to compare the results of cytological examinations of lesions of the oral cavity following fine-needle aspiration (FNA), fine-needle insertion (FNI), and impression smear (IS) with histopathological results being considered as the diagnostic gold standard.In total, 85 dogs and 29 cats were included in the study. Cases were included when histology and cytology (FNA, FNI, and/or IS) were available from the same lesion; κ-agreement and accuracy between cytological and histopathological results were calculated. Eighteen cytological specimens were excluded, with a retrieval rate of 84.2%. Of the 96 samples analysed, FNA, FNI, and IS were available from 80, 76, and 73 animals, respectively. Overall, 60/67 (89.6%) and 21/29 (72.4%) lesions were neoplastic in dogs and cats, respectively, with the remaining being non-neoplastic. For all lesions, κ-values obtained by FNA, FNI, and IS were in dogs 0.83 (95% confidence interval [CI]: 0.77-0.90), 0.87 (95% CI: 0.81-0.93) and 0.75 (95% CI: 0.67-0.84), respectively, and in cats 0.92 (95% CI: 0.87-0.96), 0.92 (95% CI: 0.88-0.97) and 0.86 (95% CI: 0.79-0.92), respectively. The diagnostic accuracies of FNA, FNI, and IS in dogs with neoplasia were 98.2%, 98.1%, and 91.8%, respectively, and in cats with neoplasia were 95.6%, 95.6% and 95.8%, respectively. In conclusion, the high agreement with histopathology suggests that cytological examinations by FNI, FNA, and IS are all appropriate methods to correctly diagnose lesions of the oral cavity in dogs and cats.