Research Communications of the 24th ECVIM-CA Congress

This study received financial support from a company (Merial). Neuter status and risk of malignant neoplasia is not well evaluated in the canine population, when excluding neoplasia not normally believed to be sex-hormone dependent. Denmark and the Scandinavian countries have a high proportion of intact dogs compared to populations from other parts of the world. In the present study it was hypothesized that there would be no difference in gender and neuter status between the population of canine patients with a non-sex-hormone dependent malignant neoplasia reported to the Danish Veterinary Cancer Registry and a general population. From August 2005 to March 2014, 3801 canine neoplasms were reported to the Danish Veterinary Cancer Registry. The total number of malignant (1788) and benign (1953) were comparable (42% and 46%). Malignant neoplasms totalled 1262, when tumors from areas of distribution with known sex-hormone dependency (reproductive organs, mammary gland, perineal), and cases with unknown area of distribution were excluded. The overall distribution of malignant neoplasia was 481 (38%) intact male dogs, 157 (12.5%) neutered male dogs, 404 (32%) intact female dogs and 220 (17.5%) neutered female dogs. The distribution was even between male and female dogs (50.5% and 49.5%). Compared to a known standard population of dogs, there was an overall statistically significant association of malignant neoplasia with neuter status in both sexes. For both genders this was significant for lymphoma, mast cell tumors and osteosarcomas,. For neutered females, but not males, there was increased risk of hemangiosarcoma, squamous cell carcinoma and malignant melanoma. These findings indicate that there might be an association between neuter status and development of malignant neoplasia but larger prospective studies are needed to evaluate the risk of non-sex hormone dependent cancers in neutered dogs.