Cancer in dogs and cats - can it be prevented?

BY Pete Wedderburn - ANimal Doctor

Published 07/07/2015 | 00:00

Cancer is expensive to diagnose and treat: prevention is better
Cancer is expensive to diagnose and treat: prevention is better

There have been great advances in the diagnosis and treatment of cancer in recent years, often by using the latest drugs and techniques available to modern medicine.

Yet cancer can still be very difficult, or impossible, to cure. And it's an expensive disease. It's costly to make the diagnosis (using techniques like MRI scans and biopsies) and it can be extremely expensive to treat (with techniques like intricate surgery, irradiation and high-priced chemotherapy drugs.  Many people have started to ask me a different question: is it possible to prevent cancer in the first place?

We all know some of the ways that we can prevent cancer in humans: obvious lifestyle changes can be made such as not smoking, avoiding too much processed meat, and protecting our skin from the sun's dangerous rays. But what about with pets? Can we prevent cancer by changing their daily habits?

The first thing to say is that "cancer" is not a single disease entity: it's a complex collection of diseases, caused by a multitude of factors, including genetics and environment. It's highly unlikely that any one thing will have broad and significant effects on the overall cancer risk. It's easy for onlookers to make claims for some dietary supplement, or nutritional strategy, but the truth is much more complicated. If there was a simple prevent-all-cancer method, we'd all know about it.

That said, I do know of eight specific ways that the incidence of some cancers in pets can be reduced.

First, malignant skin cancer of the tip of the ears and nose is common in white cats, because they have no pigment in these areas to protect the skin cells from the ultraviolet radiation in the sun's rays. The daily application of a total sun block to these areas of the body significantly reduces the risk of this cancer. All owners of cats with white ears and noses should be doing this every day just now, during the summer months.

Second, if a bitch is spayed before her first season, there is a dramatic reduction in the rate of mammary cancer, which is the most common cancer to affect female dogs. The female hormone, oestrogen, stimulates the cells in the mammary glands, priming them so that they are more likely to become cancerous. In countries where spaying is less common than in Ireland (such as Norway, where it is illegal), the incidence of mammary cancer is far, far higher. There are many reasons to get a bitch spayed, but prevention of mammary cancer is one of the most significant.

Third, castration removes the risk of testicular cancer, although some would argue that it's a radical way of dealing with a cancer risk. Cancer of anything can be prevented if you surgically excise the part of the body involved. Again, there are other reasons for castration (in particular, behavioural reasons, to stop dogs being so "male", preventing them from urinating in the house, being aggressive to other dogs and straying away from home).

In recent years, some research has suggested that spaying and neutering can have an effect on other, less common cancers, reducing the risk of some, but increasing the risk of others. It's too early to draw many definite conclusions from this research, other than to say that overall, on average, neutered/spayed pets live for longer than entire pets. So for most pets, spay/neuter is likely to be the best approach for a longer, healthier life.

Fourth, exposure to tobacco smoke in the environment increases the risk of nasal cancer in dogs, and gastrointestinal lymphoma in cats. Another reason not to smoke in your home.

Fifth, living in an urban environments seems to increase the risk of lymphoma in dogs. Moving to the countryside would be a radical way of protecting your pet against this condition, but it is something to reflect on.

Sixth, asbestos exposure increases the risk of mesothelioma in pets: just as we protect ourselves from asbestos, we should also protect our pets.

Seventh, there's one very specific anti-cancer fact: consumption of cruciferous vegetables (green-leaved vegetables such as cauliflower, cabbage,and broccoli) reduces the risk of bladder cancer in Scottish Terriers.

Which takes me on to my eighth, and final, anti-cancer tip. It's the most important one which can have the greatest impact on whether or not your pet gets cancer: choose your breed carefully. Just as bladder cancer is common in Scotties, there are many other cancers that are more common in specific breeds. This goes back to the genetic background to many cancers. Humans have created dog breeds with the aim of producing a predictable type of appearance and temperament, but sometimes not enough attention has been given to the side effects of concentrating the genes in this way. We now know that many illnesses are more common in certain breeds, and cancer is no exception. Every breed has different genetic predispositions, and you should not buy a breed of dog without first discovering the health issues that are common in that particular breed. To find out more, if you're considering a pedigree dog, visit where the pros and cons - including cancer risks - of every breed are listed. Or better again, choose a low-cancer-risk cross bred dog.

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