More on pets: part 1

Previously I posted my letter about cat sterilisation, specifically saying that it wasn’t a decision to be taken lightly. Of course that sounds radical as nearly everyone would say you should have your cat sterilised, indeed that was the very message of the piece to which I was replying and a message endorsed by the respected SPCA. So I’m taking this opportunity, with considerably more space, to further expand on the reasons for writing what I did.

I’ll admit there was a slight problem in my reply, that being that I was not familiar with the literature on cat sterilisation. However cats are not the only animals that are sterilised and I was basing my letter on Laura J. Sanborn’s article, The Long Term Health Effects of Spay/Neuter in Dogs, which I had previously encountered. The article which I read came up with these, shocking to me at the time conclusions.

On balance, it appears that no compelling case can be made for neutering most male dogs, especially immature male dogs, in order to prevent future health problems. The number of health problems associated with neutering may exceed the associated health benefits in most cases.


For female dogs, the situation is more complex. The number of health benefits associated with spaying may exceed the associated health problems in some (not all) cases. On balance, whether spaying improves the odds of overall good health or degrades them probably depends on the age of the female dog and the relative risk of various diseases in the different breeds.

This was a major change from the sort of advice which is given by most organisations, pet books and brochures for new pet owners. Indeed when I then went back to look at what was said about sterilisation it was nearly all positive, saying how it reduced cancer, eliminated unwanted behaviours, prevented puppies and generally made out that doing it made you a good, responsible person.

There was almost no mention of negative side effects, and when there was it was vague and generally played down to seem insignificant. Laura’s article, however, mentioned three studies that had found sterilisation complications to occur approximately 20% of the time. Granted the complications were generally minor but it still seems like something people should know. That was my main motivation for writing the letter.

If you look at what the information that is generally available to the cat-owning public you will find that it too is biased in favour of sterilisation with almost no mention of any possible risks or adverse effects. Hill’s Pet Nutrition gives a better description as they actually mention the increased risk of obesity and urinary problems (which may be different to the urinary diseases mentioned later). However they still have a huge bias and attempt to appeal to people’s emotions with phrases such as “sterilisation (or neutering) is the best thing you can do” and “rest assured that you are doing the best thing for your cat.”

The Hill’s site also fails to correctly distinguish whether what you are doing is for your benefit or for the benefit of the cat. In their explanation of why sterilisation is best for the cat they say that:
“You avoid the worry of unwanted pregnancy.” That’s not something the cat worries about so that’s a benefit to the owner.
“A male cat will refrain from sexual behaviour such as spraying urine and howling.” Again, neither of which is beneficial to the cat.
They also claim it makes your cat more loyal and affectionate, which, whether true or not, is a benefit only to the owner. It’s only after these that they do get to points that are advantageous to the animal.

As for the effects of sterilisation in cats, I have summarised I. M. Reichler’s paper, Gonadectomy in Cats and Dogs: A Review of Risks and Benefits and Margaret V. Root Kustritz’s Determining the Optimal Age for Gonadectomy of Dogs and Cats. Unfortunately, there is relatively little on cats compared to dogs with possible risks and benefits which had to be excluded.

-Removal of gonads means no ovarian tumours or cysts though occurrence isn’t common and can usually be cured.
-Almost eliminates uterine diseases which are otherwise common.
-Reduces risk of mammary tumours (Occurs in 2.5% of cats with average age of detection being 10 years.) by 1/7 but timing of spaying is important (91% reduced risk of malignant tumours if spayed before 6 months. Effect decreases with time and no benefit if spayed after 2 years old.).
-Almost eliminates tumours of genital tracts in females.
-Better average health for males.
-In males it reduces several hormone-related diseases, however all of them are very rare.
-Increased life span, though uncertain how much is due to operation and how much is just due to better care that those animals generally receive.

-Juvenile development of vulva, though not causing clinical symptoms. No mention was made of cats but in dogs several diseases appeared more common when the vulva were not fully developed.
-Juvenile development of penis in male cats.
-Possible increase in lower urinary tract diseases.
-3.4X increased risk of obesity.
-up to 9X more likely to contract diabetes mellitus.
-Altered bone growth rate, possibly increasing the risk of fractures.

There are always also risks related to the surgery itself but those complications are usually minor with fatalities being extremely rare.

At present it looks as if sterilisation of cats is generally for the best in terms of their health. The caveat being that there is more data available for dogs and in dogs the situation is far less clear, a situation that I believe cats will be in as we learn more. There are still differences between breeds though and whether or not a cat should be sterilised should be looked at individually for each cat.

This post is long enough so I will continue further in a second post, looking more at the ethical issues of sterilisation.


1 thought on “More on pets: part 1

  1. Pingback: More on pets: part 2 | Evidence & Reason

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