Reproductive Capability Is Associated with Lifespan ...

[minkee]

Reproductive Capability Is Associated with Lifespan and Cause of Death in Companion Dogs

It's way too early for me to try and read & decipher this, but based solely on the title I thought it something worth sharing

Reproduction is a risky affair; a lifespan cost of maintaining reproductive capability, and of reproduction itself, has been demonstrated in a wide range of animal species. However, little is understood about the mechanisms underlying this relationship. Most cost-of-reproduction studies simply ask how reproduction influences age at death, but are blind to the subjects' actual causes of death. Lifespan is a composite variable of myriad causes of death and it has not been clear whether the consequences of reproduction or of reproductive capability influence all causes of death equally. To address this gap in understanding, we compared causes of death among over 40,000 sterilized and reproductively intact domestic dogs, Canis lupus familiaris. We found that sterilization was strongly associated with an increase in lifespan, and while it decreased risk of death from some causes, such as infectious disease, it actually increased risk of death from others, such as cancer. These findings suggest that to understand how reproduction affects lifespan, a shift in research focus is needed. Beyond the impact of reproduction on when individuals die, we must investigate its impact on why individuals die, and subsequently must identify the mechanisms by which these causes of death are influenced by the physiology associated with reproductive capability. Such an approach may also clarify the effects of reproduction on lifespan in people.

[Nettle]

I love these, Minkee- they really make us think.


That summary seems a very long-winded way of saying absolutely nothing



It would be an interesting study if all the variables (diet, exercise, expected lifespan, general care) were taken into account, but not one to affect humans. Because humans go out of season: they don't come into season. And humans have a menopause which other mammals don't (may be an exception for apes - I have conflicting info here). Most male scientists never 'get' this important difference.

The other caveat is - it is very difficult to prove a negative. In this case, how long would this mammal have lived if it had done the other thing?

It's good that they differentiate between being capable of breeding and actually having bred. A lot of agencies don't do this.

But to me, husbandry is the vital component - the animals that have the best care are most likely to live longer.

[gwd]

It would be an interesting study if all the variables (diet, exercise, expected lifespan, general care) were taken into account,

another variable with b*tches would be were they ever bred and if so, how many litters. .......

[Nettle]

It would be an interesting study if all the variables (diet, exercise, expected lifespan, general care) were taken into account,

another variable with b*tches would be were they ever bred and if so, how many litters. .......

Not to mention how many pups each litter, how easy/difficult were the births, was there any illness eg eclampsia..........

[jacksdad]

I finally got a chance to read the actual study the other day. For me, it actually raised many questions, while answering none. And depending on what information a follow up study finds in regards to why spayed/neutered dogs seem live longer, there might be some uncomfortable ethical questions that result. The study really and truly does not offer proof that spayed or neutered dogs live longer do to being spayed or neutered, a point they go to great lengths to avoid and only address in a couple sentences at the end.

As to the uncomfortable ethical questions, the one that came to my mind was the result of hearing a claim (I don't have any proof to back this claim up, just illustrating a possible ethical issue) that 50% of all dogs over 10 will die of cancer.

IF spaying and neutering does in fact cause unnaturally longer life (remember natural life span has to be bench marked off of intact dogs since they are as nature meant them to be), and it is an established and accepted fact that 50% of dogs over 10 die of cancer..... that raises some potentially uncomfortable ethical issues with spay/neuter IF intact dogs are not dieing of cancers in significant numbers due to unnatural life spans.

To me, just illustrates how we need to read studies critically and carefully. In this studies case, I am thinking it might just need to be filed under interesting but provides no actionable data or information to make a choice or advice regarding spay or neuter. there are many, many possible other cause of longer life or shorter life that one needs to take into an account, that this study does not before you can truly draw a conclusion. An example is this study covers 1984 to 2004. In 1984 what percentage of dogs were spayed and neutered verse not would need to be taking into an account. as would medical advances. So, for example, if MOST dogs in 1984 were not spayed/neutered and veterinary medicine didn't have cures for some of the things they do now, that could create one impression. If in 2004 MOST dogs ARE spayed/neutered, and Veterinary medicine now has cures for somethings that killed in 1984, that also needs to be taken into an account.

So this study really does create a lot more questions than it answers. nd it also illustrates how much we do not know about the effects of spay and neuter on a "massive" scale to the dog population as a whole as well as the individual.

Just so people who may not know my general position on "things". More often than not, I will choose to come down on the side of the individual over the "community". and that is how I view the spay/neuter question. I am NOT overly concerned about the "community", I am GREATLY concerned about developing good data to help a dog owner make the best choice possible about the dog they are responsible for. And right now, spay/neuter is WAY slanted in favor of the "community" at expense of the individual.

[Nettle]

From a nutritional point of view, the beginning of this study covers a period of years where dried processed food was very much the norm, and only in the 2000s has natural feeding made a significant comeback (I started raw feeding in the mid 1980s and it was as if I was advocating witchcraft). So on nutritional grounds alone this could do with investigation.

If 50% of dogs die of cancer, what do the other 50% die of? We need to know. We also need to know which cancers.