Having looked at your post further, I forgot to address this issue of diagnosis bias. Of course the mortality study looked at dogs that were diagnosed with cancer, since mammary masses that are not cancerous of course don’t kill the patients, so they don’t have a mortality rate. Other research shows that about 50% of mammary masses are benign, so we have to make sure we are talking about the same things. If you ignore a breast tumor in a bitch, half the time it will be benign and will grow slowly but never spread or kill the dog. Unfortunately, unless you biopsy the tumor you have now way of knowing if it’s cancerous, so you’re just rolling the dice.

The statistics above refer only to malignant or cancerous tumors, so the fact that you see lots of lumps which don’t kill the dogs doesn’t change the numbers as far as how common true cancers are or what their mortality rate is. All it means is tat if we were counting benign lumps, we’d see twice as many tumors in intact females as the numbers above indicate, but only have of them would be serious.

The underlying issue, of course, is whether the risks of spaying outweigh the benefits overall. I consider mammary cancer itself a significant factor since it is common and deadly. However, as you admit, pyometra and other factors argue for spaying even if we ignore the issue of mammary cancer, and as I illustrate in detail in the reference I link to above, the risks of spaying are far less than the benefits, so we must not lose sight of the total picture and the overall welfare of our dogs.

As for how common the disease is, here’s some information:
“A study in Norway, where almost all female dogs are intact, found an overall incidence of malignant mammary tumors of 53.3%, with significant variation in risk by breed.[14] A UK study found mammary tumors to be the second most common type of tumor, with an incidence 205 tumor per 100,000 dogs per year.[15] A Swedish study found an incidence in intact females of 1% at 6yrs of age, 6% at 8yrs, and 13% at 10 years when the study was terminated[16]”
14. Moe L. Population-based incidence of mammary tumors in some dog breeds. Journal of Reproduction and Fertility 2001;57:439-43.
15. Dobson JM, Samuel S, Milstein H, Rogers K, Wood JL. Canine neoplasia in the UK: estimates of incidence from a population of insured dogs. Journal of Small Animal Practice 2002;43(6);240-6.
16. Egenvall A, Bonnett BN, Ohagen P, Olson P, Hedhammar A, von Euler H. Incidence of and survival after mammary tumors in a population of over 80,000 insured female dogs in Sweden from 1995 to 2002. Preventative Veterinary Medicine 2002;69:109-27.

These are not studies of severe cases with metastasis, these are surveys of populations of dogs over long periods of time, and they show the rate at which dogs that are intact and healthy at the beginning eventually develop mammary cancer.

I know it is difficult to believe that a disease could be so comon when you personally aren’t aware of a lot of cases, but unfortunately our personal experience is often unreliable at making such mathematical estimates, which is why we need scientific research.

The population of show breeders is *obsessed* with disease, and I am very serious about that. If there were a lot of bitches dying of mammary cancers or their sequelae we would not only know about it, we’d be funding studies.

Ms. Kimball,
If you look at this article (Sorenmo KU, Shofer FS, Goldschmidt MH. Effect of spaying and timing of spaying on survival of dogs with mammary carcinoma. Journal of Veterinary Internal Medicine 2000;14:266-70.) you will see that 59% of the dogs with mammary cancer eventually died from their disease despite treatment. Dogs spayed before 2 1/2 years of age were far less likely to develop cancer and survived longer if they did than dogs left intact or spayed later, though spaying also had some benefit in terms of survival if done at the time the cancer was diagnosed.

As for your personal experience of almost never seeing an intact female with mammary cancer, I understand why it gives you the impression the disease isn’t that common, but such anecdotes aren’t as reliable as good epidemiologic evidence, and the evidence shows that mammary cancer IS very common in intact bitches.

Finally, the risk of mammary cancer is FAR greater than that of osteosarcoma, so recommending waiting for 1 or 2 heats before spaying will result in far more deaths from mammary cancer than will be prevented by the possible decrease in osteosarcoma rates.

I suggest you look at the details in the article I linked to above, which also cites the specific studies the numbers come from so you can read them for yourself.

Aren’t heat cycles taxing & stressful on animals (& not just their owners/guardians!)?

I noticed our foster cat (a pregnant stray that walked in) not eating or sleeping regularly, loosing weight and shedding a lot when she was in heat.

She was also urinating outside the litter box, mostly up high on the wall near and on the bathroom vanity. This stopped after spaying. I’m guessing she was trying to attract a male. Her two kittens were the only intact males in the house.

Wish our local vets were pro early spay/neuter – it would have made it easier for me to find new homes for the kittens. I was told to wait until they were six months old, so that’s when I had it done.

I think Dr. Root-Kustritz’s report for the CHF is better than the NAIA’s. It’s here: http://www.akcchf.org/pdfs/whitepapers/3-23-08DiscoveriesArticle.pdf

It’s rather inescapable at this point that neutering males is actually harmful on balance, not helpful. The research has actually prompted me to remove my neuter requirement from my puppy contract; they are still obligated to not breed but they do not have to neuter. Spaying bitches still wins because of pyometra, but in large-breed dogs the benefit of waiting until after the first heat (or sometimes the second or third) in terms of protecting against osteosarcoma is DEFINITELY going to win over the relatively minor risk of mammary tumors.

I did a huge amount of research on mammary tumors and found no indication that mammary cancers have a 50% mortality rate. What I found was a study that said that the survival rate was low if the cancer had substantially metastasized to the lymph nodes and had broken through the skin. That I believe; you ignore ANYTHING that long and it’s going to kill your dog. However, as a show breeder I know and know of hundreds if not thousands of intact bitches, most intact into good old age, and have never heard of a single one with fatal mammary cancer. We know they occasionally get the little lumps, we watch them carefully, and if they look like they’re growing we take them out. However, even those are (in my experience) rare. Rarer than lipomas, FAR rarer than pyometra.

I’ve always found it fascinating that of all the ways you can prevent dogs from breeding, the one that’s the Savior Of The Whole World is spay/neuter. Why not fences? Leashes? Training? Why is neutering more responsible than a leash and some common sense?

If you don’t have any of those things, and are unwilling to put them into place, by all means neuter. I’d say that most pet owners would be well-served to spay even WITH those things, because of the pyometra risk. But there’s really no reason to demonize testicles; they seem to be very protective to the dog and intact dogs are, by and large, absolutely lovely to live with.

I’ve found that more and more serious performance owners are keeping their dogs intact because of the protective nature of testosterone on, among many other things, ACL/CCL injuries. These dogs are, by and large, never bred (of course, neither are most conformation-bred intact dogs!) and have a happy life, including interacting with a ton of other intact dogs and even in-heat bitches.

Oh, and having lived through a ton of heat cycles, there’s no howling. If you don’t have an intact male in your house, a heat cycle is one big snooze-fest. No behavioral changes to speak of, most bitches don’t even need diapers. And I’ve *never,* no matter where we lived, from super-rural WV to urban Chicago, had a male dog show up. When we do have stud dogs in the house, they are only agitated if they can’t be near whoever is in heat. Experienced stud dogs only get worried on the actual day or two of fertility anyway. So we crate them next to each other, he licks the bars and breathes heavily for a night or two, and then it’s over.

If someone is enough of an idiot to not even know if their dog is pregnant, widespread spay/neuter is not going to save them. That’s a stupidity problem, not a genital problem.

I’m going to risk speaking against s/n (gasp!). Let me preface this by saying all three of my (rescue) animals are spayed/neutered – but I will think carefully before doing this to my next one. Here’s why.

I’m a natural cynic – when I see everyone saying something is good, I automatically go looking for evidence. It’s not easy (for me, a non-vet) to find evidence against s/n. It’s very trendy. And for good reason – no one wants to see unnecessary euthanasias, crowded shelters and unwanted litters of adorable kittens.

But I don’t think spaying/neutering every animal is the answer. I think it’s a band-aid. The answer is to educate people into becoming responsible pet owners.

Unfortunately education ain’t easy. So we focus on s/n, pulling resources away from education as a result.

I also don’t think s/n should be applied as a blanket policy. Now, I’m not suggesting that the vets who write these two blogs would blindly s/n any animal that walked through their door. Reading their writings, I’m sure they would look at it on a case-by-case basis. But I’m not sure shelters, rescues, low-cost s/n clinics etc do. And without education, owners don’t know what questions to ask. For it seems there are definite risks to s/n.

Now, I am not a vet. And if those who are can refute the points in this document I would be quite happy. But it looks quite well referenced.

http://www.naiaonline.org/pdfs/LongTermHealthEffectsOfSpayNeuterInDogs.pdf

And so it makes me question – while s/n may be good for the overall population, am I really doing what’s in the best interest of my dog or cat?

http://www.skeptvet.com/index.php?p=1_23_Benefits-Risks-of-Neutering