Cancer occurs commonly and spontaneously in pet cats and dogs. Canine and feline tumors share morphologic, etiologic, clinical, and molecular features with human tumors. Thus companion animal cancer models are at least as relevant and, in some ways, more so than the popular and pervasive rodent models.

Opportunities exist to utilize spontaneous cancers in dogs and cats in basic, epidemiologic, and preclinical investigations. We have been studying comparative carcinogenesis using canine and feline tumors, including gastric, mammary, bladder, head and neck, and bone cancers. The development of an epidemiologic component to this work is a natural extension of our investigations for many reasons:

1. There are almost 70 million pet cats and over 60 million pet dogs in the United States making pet animals widespread, potential environmental sentinels. At least 30% of dogs and cats will develop cancer.
2. Humans share their lifestyle and environment with their pets.
3. Existing studies suggest that humans and pets share certain environmental risk factors for cancer, such as environmental tobacco smoke.
4. Risk of cancer varies based on dog breed, thus canine studies can be designed to investigate gene-environment interactions.
5. Life span and latency periods are short compared to humans, permitting studies of lifetime risk and the effects of intervention that can be completed in relatively short time frames.
6. Pet owners are highly motivated to take part and are extremely compliant.
7. Studies of pet animals in clinical settings are subject to limited regulation and are viewed favorably by IACUCs.
8. Shorter studies coupled with the lower costs of veterinary care makes companion animal studies relatively inexpensive.

As one of only a few institutions in North America that contains a cancer center as well as a veterinary school on the same campus, the University of Minnesota is uniquely situated to exploit the pet animal cancer resource to benefit both people and animals. The University of Minnesota Veterinary Medical Center (VMC) is the only veterinary referral center in the Twin Cities metropolitan area and has a referral base of 500 small animal practices in the region. The veterinary staff of the VMC, which includes about 50 board-certified specialists, evaluates over 40,000 cats and dogs and diagnoses thousands of new cancers each year. The pet population has great potential to expand the capability of the animal model armamentarium and provide a platform for interdisciplinary research.