Survival and projection analyses of the effect of radiation on beagle dogs

The Cox proportional hazard model is used to identify important covariates related to survival for this beagle dog study. The Weibull and the Gompertz parametric probability models are used to fit the survival curves for 1680 beagle dogs given whole body Co-60 gamma radiation or sham irradiation and held for life-span observation. Deaths from cancer and noncancer are the primary diagnoses. Of dogs dying from cancer, female dogs showed significantly greater cancer mortality (p < 0.0001) than did males, and irradiated dogs had significantly greater cancer mortality (p = 0.022) than did the unexposed dogs, by either the Weibull or the Cox model. However, there were no sex and exposure differences in mortality for dogs dying from noncancer causes. The fitted Weibull and Gompertz models have been successful in projecting the actual mortality experience in this experiment and could be used for similar life-span experiences.