Our Archives: cancer

A surprising question……. 

Since the 1970’s vets have advocated neutering for prevention of cancer in dogs and cats. There is evidence for a reduction in breast cancer in neutered female dogs⁽¹⁾ and cats ⁽²⁾. Surgical neutering also eliminates the risk of testicular or ovarian cancer. 

When talking about neutering, vets often list a series of diseases that neutering can help prevent. Prostate disease is often near the top of that list - but is it true? What are the impacts of neutering on prostate disease in dogs? Our vet blogger Sian has been digging into the science in this, the first of our "Neutering Week" posts.

Brain tumours can occur in dogs, just as in people, and account for 2-5% of all canine cancers. When they happen, they can be devastating, as although there are many different types of tumour, most are eventually fatal, with or without treatment. Here we will cover some basics about brain tumours, which enable us to later navigate some of the difficulties associated with picking up the signs and diagnosing them.  

It happens to most of us at some time or another. You bend down to give your pet an absent-minded stroke, or a tickle behind the ear, or a tummy-rub perhaps, and your fingers close on something - a bit of pet - that wasn't there before: a lump. And of course, once you've found it, you can’t un-find it. Your mind begins to whirl. Supposing - just supposing - that the lump is actually cancer?

It can be very worrying when you notice your cat to start to lose weight, especially if they’re an older cat. Weight loss conjures up terrible thoughts and googling often makes things worse - a symptom as vague as weight loss can mean so many different things it’s bound to be a scary page of results. We tend to notice problems in cats slowly. They’re masters at hiding signs of illness and disease and often live very independent lifestyles, some even going for several days without being seen. The fact that most cats toilet outdoors, unaccompanied, means that you may not notice symptoms such as diarrhoea or producing large volumes of urine. And since many cats have dried food down all day, changes in appetite can be hard to spot at first. This means that weight loss is often the first symptom that people notice in their cats, with other symptoms only coming after you start to keep a closer eye.

I knew I wasn't going to breed from my Hungarian Viszla so I made the decision to have him neutered which I did at six months old. Since then I have been told by the breeding fraternity that neutering at such an early age is a factor in dogs getting bone cancer. I cannot bear that I may have done something in good faith that could affect my beloved dog's future health. What is the truth?

This question from a VetHelpDirect reader is an increasingly common query from pet owners responding to internet rumours and discussions that are doing the rounds. As is often the case, the truth is complicated: we still do not know everything about the impact of spay/neutering, but we do know that there are pluses and minuses to having the operations done.

In the past, it was more-or-less universally agreed that early spay/neuter was the best choice for all dogs and cats. New information from recent studies means that this one-size-fits-all advice now needs to be modified. It seems that spay/neuter of some breeds of young dogs may increase the risk of some some types of cancer. At the same time, it should not be forgotten that the operation also reduces the risk of other (common) cancers. A balanced view now may be that the decision needs to be made for an individual, after considering all factors, rather than just saying "early neutering is always best".

It does sound to me as in your case, with a Viszla, it was the correct decision. Early neutering is still strongly recommended for nearly all dogs as the best way to ensure that a dog is a good family pet. There are many behavioural advantages, such as stopping male dogs showing sexual behaviour, urine marking etc. And there are many health benefits too - reducing prostate disease, reducing certain types of cancer etc. And bone cancer is rare in Viszlas.

For female dogs, there are also many benefits from spaying. The operation eliminates the risk of unwanted pregnancy, dystocia and the physiological and behavioural changes associated with the six-monthly reproductive cycle. It eliminates the risk of pyometra, which occurs in 23% of intact females and kills approximately 1% of intact females. Mammary tumours are the most common malignant tumours in female dogs, and spaying before 2½ years of age greatly reduces the likelihood of this cancer.

Neutering and spaying has other beneficial effects on a society-wide basis: it prevents dogs from straying and dramatically reduces the problem of unwanted pups.

What about the negative aspects? A comprehensive review paper published in 2007 provides a detailed catalogue of the potential negative risks which seem to be more in some breeds and some cancers than others (e.g. more osteosarcoma in giant breeds like Newfoundlands and St Bernards). A more recent study on Golden Retrievers found an increased risk from other cancers and some joint diseases from early neutering but the study has been criticised by statisticians and other scientists as being potentially biased and not representative of the general population of dogs. It's likely that other studies are in the pipeline, so it's worth keeping an eye out for these in the coming years.

When reading these studies, it needs to be remembered that a big increase in the risk of a rare cancer may not be as significant to a pet as a small decrease in the risk of a common cancer. It is not easy for pet owners, unfamiliar with judging medical data, to assess these types of situations. What should pet owners do? Refuse to spay/neuter their pet, then blame themselves when their male dog develops anal tumours or when mammary cancer affects their female dog? Or go ahead and spay/neuter, then beat themselves up when their pet develops osteosarcoma?

The best answer is that there is no perfect choice. The take home message is that you should not ignore the subject: all pet owners should discuss this with their vet. A decision should be made after addressing all of the issues above. Only in the fullness of time will you know whether it was the right or wrong choice.

The most important issue is that you carefully consider the various implications: at least then, regardless of the outcome, you will be able to look back and say " I did my best to do the right thing".