Hey everyone,
Said I'd post the response from one of the articles biased toward spaying and nuetoring brought up in a previous thread. It was so long ago I don't even remember what it said...memory serves me it was more opionionitive then statistical. I'm not saying I'm either way on the subject....just sticking to my word to post a response for your reading if they responded. My question to them was for their opionion on an article source sited and based on studies and statistics leaning toward mainly not nuetoring male dogs. Here is their response...take it as you wish.
In a message dated 6/19/08 2:45:12 PM,
Feedback@veterinarypartner.com writes:
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Sent: Tuesday, June 17, 2008 5:33 PM
Subject: Veterinary Partner Feedback
>A visitor to VeterinaryPartner has submitted the following feedback.
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> User's Name: Jami
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> Question:
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http://www.naiaonline.org/pdfs/LongT...uterInDogs.pdf
> What do you think about this article that is source sited and based on
> statistics?
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> URL:
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Spay/Neuter Behavior Benefits - VeterinaryPartner.com - a VIN company!
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> HTTP_USER_AGENT: <%= HTTP_USER_AGENT %>
It has been a while since I read this completely and it is similar to a review published in the Journal of the American Veterinary Medical Association. The conclusion of the two analyses seems to be very different. The bottom line comes down to a principle of basic scientific analysis: Correlation does not imply Causality. There are a number of retrospective studies that look at a broad statistical analysis of dogs or cats presenting to a university or universities and end up with a specific diagnosis. This group is broken into breed, age, sex, prior medication history and whatever categories the researcher can think of that might provide a pattern. This is all well and good and can provide some insight but there is a bias always because these are animals that were referred to a teaching hospital meaning that the group of dogs with that disease that recovered, died or were euthanized at their regular vet's office are not included in this group. It is common to se a bias towards animals being diagnosed with disease if they live primarily indoors which some would like to interpret as meaning the disease in question is associated with some sort of toxin (fire retardants or whatever) when more likely it means that animals living primarily indoors are observed more closely and are more likely to see the vet. Another example is the possible increased susceptibility of the Labrador Retriever to rimadyl related liver disease. The lion's share of case reports are in this breed; however, it turns out the lion's share of rimadyl users are also this breed. Probably we are just seeing the same incidence of the problem in this breed but so many more Labrador's are exposed that it looks like there is a sensitivity there. Again, correlation does not imply causality.
The spay/neuter information presented in these articles is the same. As an example let's make up a disease, say something as rare as most of the conditions mentioned in this article. Let's say 90% of the dogs diagnosed are neutered or spayed. Does that mean that there is a causal factor at work or does it mean that the unneutered animals with the disease never entered the study for an assortment of reasons. There is also the issue of small groups reviewed: let's say out of 18 dogs with some disease 12 were neutered and 6 were unneutered. That means twice as many dogs with that disease were neutered but it is fairly easy to see with such a small number examined this is a misleading way to summarize the information.
In the JAVMA review it was pointed out that it is not really worth trying to reduce a dog's chance of getting a rare disease to even rarer if in doing so you are sacrificing an greatly increased risk of a common disease. Mammary tumors in the female dog have a 25% incidence in unspayed dogs (a huge incidence). Is it really worth dropping your dog's risk of X cancer from 1% to 0.5% and increasing the risk of mammary tumor development from 0.5% to 25%? Of course it isn't. In the end these little statistical variances that may not even represent a true cause-effect relationship between disease and sterilization are not worth having a pet with unacceptable behaviors (the chance of an unsterilized dog dying in the shelter is higher than the chance of a sterlized dog getting any of the diseases you could ever study), a pet with mammary cancer or prostate hyperplasia (likely sequellae of being unsterilized), and probably not worth paying the increase in taxes that comes from the city having to euthanize all the unwanted dogs and cats in the shelter annually. In the end only one medical condition w/an increased incidence in sterilized animals was common enough to warrant a second look and that is the ruptured cruciate ligament but this is such a multifactorial problem that even that is worth trading increased risk in one of the factors for all the benefits of sterilization.
hope this helps w/perspective.
AltheaVet