By Dr. Alison Book, DACVIM Oncology

This is the question pet owners are most likely to ask, and often the most important questions are the most difficult to answer. This question is no exception. As pet owners and veterinarians, we understand how important it is to you to know how long you can expect your loved pet to live, and our goal is to give you the most accurate estimate possible. Here are some things we want you to keep in mind in order to best understand your dog’s or cat’s prognosis.

When we give a number of months or years as a time frame for life expectancy, we are usually referring to something called the “median survival time”. So what is a median survival time?

What Is a Median Survival Time—and What Does it Mean for My Dog or Cat?

Well, from a scientist’s perspective, if you took a group of dogs that all have the same type of cancer and recorded the amount of time each of them lived from the time of diagnosis to death, the median would be the middle number in that group. What this tells you as a pet owner is that, in reality, there is a range of survival times that can occur depending on certain factors that are individual to each dog or cat and their particular cancer. While we want to provide you with the most accurate assessment that we can, the truth is that anytime we are talking statistics (ack! Don’t be scared!), we need to remember that the quality of the information can vary. As a general rule, the numbers are more solid for cancers that are more common and have been studied more extensively.

So, what does this mean for the life expectancy of your dog or cat?

It means that if your pet has a common cancer, chances are, we are going to be better at determining their prognosis. And if your pet has a rare cancer, we don’t have as much data on which to base our answer, so our estimate may not be as accurate. Veterinary oncology is an evolving field and the “numbers” continue to change as we learn and advance.

Factors that Affect Life Expectancy

When treating pets for cancer, many factors affect the range of possible survival times. Some factors are specific to the pet such as overall health, general life expectancy, or specific circumstances known to affect the prognosis of a cancer. Some factors are related to the individual cancer, such as rate of growth or susceptibility to treatment. It is also important to realize that individual families will choose different treatments for their pets and have diverse ideas about when it is time to stop treatment or elect humane euthanasia. We would be happy to sit down with you and talk about the factors that specifically affect your dog or cat.