An epidemiological analysis of a canine-biopsies database compiled by a diagnostic histopathology service.

A case-control study was carried out on data from 21,371 canine tissue biopsies submitted to the external histopathology diagnostic service at the University of Glasgow Veterinary School (GUVS) over a 12.5-year period. Biopsies were received from 545 privately owned and charity veterinary practices located throughout the UK. The overall prevalence of neoplasia in samples with a confirmed diagnosis was 58.7%. A total of 156 pure breeds were represented in the dataset, with 22.2% of samples originating from mixed-breed dogs. Univariable and multivariable analyses assessed the effects of sex, breed, age and site on the likelihood of a diagnosis of neoplasia. Logistic regression showed that the highest odds ratio was associated with the mammary gland (OR=6.53;skin=the referent category). Using the Labrador retriever as the referent breed, Boxers had increased odds of neoplasia; the German shepherd dog and Doberman were among breeds with decreased odds ratios. Intact females and dogs over the age of 10 years were (unsurprisingly) also high-risk groups. Potential sources of bias influencing the dataset include the relative ease with which clinical abnormalities of the skin and mammary gland initially are detected by sight and/or palpation, compared with other organs. The high prevalence of biopsies originating from the skin and mammary gland is also likely to reflect the readiness of the veterinarian to biopsy lesions in these sites, compared with sites within the body cavities. The findings confirm many of the perceived risks for neoplasia based on previous clinical descriptive and univariable investigations. The results might also assist the pathologist in prioritisation of biopsy examination in busy histopathology laboratories.