There is a growing interest of scientists in using various distribution models in the detection of incidence, management, and treatment success of cancers in both humans and animals. This study presents a new life model named Weibull-Rayleigh (WR) distribution for estimating the incidence of vaginal cancers in laboratory animals. The data is used for rats in which carcinoma was induced by using DMBA and the proposed distribution was applied to estimate detection accuracy. Several mathematical characteristics including moments, moment generating function, entropy, order statistics, and quantile functions were calculated. The method of maximum likelihood was followed to estimate the various model parameters. It was found that the newly proposed Weibull Rayleigh distribution was valid in all respects for the real lifetime data with much better accuracy. The newly proposed distribution will enable researchers to work out on the incidence of carcinomas among animals with more accuracy.