The incidence of neoplasia in the canine and feline patient populations of private veterinary practices in southern Ontario.
This thesis is an investigation into the use of the computerized medical records of private veterinary practices for the collection of epidemiological information on canine and feline neoplasia. The patient populations of 5 veterinary practices in Ontario were characterized retrospectively over a 1 to 10 year period. The median age of both dogs and cats increased, the proportion of purebred dogs increased and the proportion of purebred cats decreased over the 10 year period. All neoplasms submitted for histopathological confirmation (HQ were identified retrospectively from histopathology records and compared with the corresponding patient populations in order to calculate the hospital-based prevalence of HC neoplasia over the 10 year period. All new neoplasms, both HC and non-HC, were identified prospectively over a 3 to 18 month period to determine the incidence of neoplasia for the 5 practices. The incidence rates of benign and malignant neoplasia in dogs were 3,965 and 852 neoplasms per 100,000 dog years respectively. The corresponding incidence rates in cats were 429 and 319 neoplasms per 100,000 cat years respectively. The most common malignancies of dogs and cats were mast cell tumour and squamous cell carcinoma respectively. Forty-nine percent of malignant neoplasms and 23% of benign neoplasms were HC in dogs. Differences in the proportions submitted for histopathology were evident between types of neoplasia. Intact dogs had a lower risk of benign neoplasia than neutered dogs. American Cocker Spaniels had an increased risk for both benign and malignant neoplasia, as compared with mixed breed dogs. Golden Retrievers were also at increased risk for malignant neoplasia, while Lhasa Apsos and Bichon Frises were at decreased risk for benign neoplasia. Using the computerized medical record systems of the participating practices proved to be a viable method for collecting data on patient populations and neoplasia occurrence. Future epidemiological studies of neoplasia in companion animals based on the patient populations of private veterinary practices will be facilitated by encouraging practitioners to more fully utilize their electronic medical record systems, by the development of a standardized nomenclature and coding scheme, and by a better understanding of how to effectively conduct practice-based research.