Good general husbandry and regular veterinary care remains the most reasonable cancer-prevention approach for most pet owners

By Brennen McKenzie, MA, MSc, VMD, cVMA

One of the most common and dreaded diseases we see in small-animal patients is malignant neoplasia. While the data on exactly how many dogs and cats get cancer is complex and uncertain,1 there is no doubt it is common, especially in older animals.

It is often stated one out of four or even one out of three dogs will eventually get cancer, and perhaps one in five cats. The source for this estimate is hard to track down, and there is likely significant variation depending on region, breed, and other variables. However, clearly cancer is a significant cause of illness and death in companion animals.

There is no single reason why so many dogs and cats get cancer. It is rarely even useful to think of cancer in terms of single causes, since neoplastic transformation, and the survival and spread of neoplastic cells is a complex process, typically requiring multiple events at many different levels to occur.

Genetic and epigenetic factors may predispose to dysregulated cell proliferation or may impede the action of tumor-suppressing mechanisms. Environmental factors may further encourage the growth of cancer and damage an animal’s defenses. As clinicians and pet owners, we are better off thinking in terms of risk factors than causes. This helps us focus on which risk factors can potentially be modified to make cancer less likely to harm the health of our patients and pets.

There are a number of strategies that have proven effective in reducing cancer incidence in humans. Many of these may also be beneficial for companion animals, though often we lack the research evidence to demonstrate the true value of particular approaches. Judicious extrapolation from evidence in humans and lab animals is a necessary evil in veterinary medicine, and currently it is the foundation upon which we must build rational cancer prevention strategies.

The interventions we should consider fall into two broad categories: elimination of identifiable root cause for specific cancers, and general reduction of risk for one or more cancers through interventions that address contributory causes.


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