Canine tumor development and crude incidence of tumors by breed based on domestic dogs in Gifu prefecture

Abstract

We analyzed the status of tumor development in dogs by breed based on tumor cases that presented to the Department of Veterinary Pathology of the Gifu University for diagnostic examinations over eight years (2005-2012). We also calculated the crude incidence of tumors in dogs by breed based on the results of a survey conducted in 2011 in Gifu Prefecture. The most common sites of tumor development included the skin, digestive organs and mammary glands. Smaller dogs showed a tendency to have a higher incidence of breast tumors. We thus identified dog breeds with a higher crude incidence of tumors (Bernese mountain dog, golden retriever, corgi, etc.) and those with a lower crude incidence of tumors (Pomeranian, poodle, Chihuahua, etc.). Unlike the current trends for domestic dogs in the US and Europe, Japan has a higher number of small dogs as pets; it is therefore necessary to develop a policy for canine cancer specific to Japan.

Fig. 1.

Questionnaire regarding domestic dogs receiving RV in 2011 in Gifu Prefecture.

Fig. 2.

Distribution of the age at the time of diagnosis of tumor cases classified by sex. The age of the dogs diagnosed as tumor cases at the time of the examination request is shown in the graph classified by sex. Analysis of age of the samples by pathological classification revealed that the mean age of developing tumors in male dogs was 10.4 ± 3.0 years (mean ± S.D.) and that in female dogs was 10.4 ± 2.8 (mean ± S.D.), showing no significant difference in the age between males and females.

Fig. 3.

Ratio of benign and malignant tumors by dog breed. The ratio of tumor and malignant tumors by dog breed was statistically calculated by the chi-square test. The result was “chi-squared=130.65, P-value <2.2e-16”. These results indicate that between each dog species and whole dog species has a significant difference in Fig. 3 (P<0.05). Additionally, we performed residual analysis to clarify and confirm this further. The bold black line shows the mean of the ratio of malignant tumors in all dogs. ★: The ratio of malignant tumors was significantly lower in the following five dog breeds: YT (32.1%), MAR (42.4%), PD (44.4%), SZ (48.0%) and DAX (48.2%) (P<0.05), while the ratio of malignant tumors was significantly higher in the following seven dog breeds: LR (63.2%), CG (65.9%), SIB (68.1%), SSD (69.0%), CW (70.0%), BG (73.4%) and BMD (80.0%) (P<0.05).