Uh, I don't think mammary tumors are rare in dogs. While 50% are cancerous I see a LOT of them in rescue.
Not basing this on any article or study....just saying what I see a lot of.
I do believe there is zero risk of mammary tumors in a dog that is spayed before her first heat.

:thumbup: I will always spay females before there first heat unless there is some kind of health issue. There is very little that says it's bad with just about little to no science to back that up and a lot more showing it is good with science backing it. You may not be able to prevent most cancers but you can this one! Not a risk I'm willing to take.

My friend's dog had a mammary tumor from not spaying her. $5,000 and the dog has had complications from palladia therapy and the cancer itself. Lucky for the dog she has an amazing owner. She apologizes to her daily for being ignorant and not spaying her. It's the real life stories like this that paint a more realistic picture than someone online giving me a interpretation/slanted view of "research."

:thumbup: that's very true.

Yeah, you have been telling me about her. So sad. There are SO many people who are not aware that this cancer can be prevented. I have seen it time and time again over the years.

REal life stories are all fine n good and are very sad, but they are anecdoctal
, but research looks or should look at a large sample size.


Now here is one such study out of Sweden, you will recall that Sweden does not allow s+n unless for medical reasons:


Breed variations in the incidence of pyometra and mammary tumours i... - PubMed - NCBI This study shows a rather large cross section of dogs - info gleaned from I believe an Insurance company. It shows a higher rate of both mammary cancers and pyrometra than I have seen in North American studies. And as the abstract was only available to me, I don't know if that study only looked at 2 health concerns.


Again the decision to s+n should be a well thought out one, taking into account the breed you own, your particular dog and a comprehensive understanding of all risks vs benefits.

Canine Mammary Tumors | College of Veterinary Medicine

From the above link:

Canine Mammary Tumors

Mammary tumors are extremely common in dogs; approximately 50% of them are malignant. Mammary tumors are more common in intact than in spayed females; in fact spaying before the first or second heat cycle significantly reduces the risk of developing mammary tumors. Median age on presentation is 10 to 11 years. Dogs fed a high-fat diet or overweight at 1 year age are at increase risk of developing mammary tumors. Appropriate early treatment, even if the tumor is malignant, is often curative.

https://www.acvs.org/small-animal/mammary-tumors

From the above link:

Mammary tumors are more common in female dogs that are either not spayed or were spayed after 2 years of age. The risk of a dog developing a mammary tumor is 0.5% if spayed before their first heat (approximately 6 months of age), 8% after their first heat, and 26% after their second heat. Cats spayed before 6 months of age have a 7-times reduced risk of developing mammary cancer and spaying at any age reduces the risk of mammary tumors by 40% to 60% in cats.

I have thought it all out well and have spayed/neutered every dog I own at the earliest age I could. Many were already adults when they came to me.

For the life of me I don't understand people sitting on an online forum encouraging people to ignore the facts that are already known and put their dogs at risk. I also don't understand with all of the oopsie pregnancies we see on this forum, how someone would continue to encourage people to leave their pups intact.

I suppose it goes with the old: To each his own...and each has his/her opinion. Anecdotal you say? Yes, I believe that most of this anti spay/neuter is a bit on the anecdotal side. The research out there is not as convincing as previous research that encourages it.

No it's not anecdotal. Her vet told her this was the reason: lack of spay. Since he is a surgeon in a large vet hospital, I think he would know. Similarly, the dog's oncologist also agreed. I guess they're lying???

From the abstract of that paper (which has phenomenally large sample sizes):

"In all breeds, the overall proportion of the bitches that developed disease by 10 years of age was for pyometra 19%, MTs 13%, and either or both of two diseases 30%"

A 30 percent chance of developing pyometra or mammary tumors in unspayed dogs seems like an awfully high risk to take, unless there are factors that counterbalance the risk. The abstract doesn't give the data for Yorkies, but if the rate is anywhere near 30%, that seems like a strong argument for spaying before first heat. If I have time, I'll try to check out the full text of this article on Monday and I'll let you know if it has data specific to Yorkies.

Thanks Phil that would be good if you can do that. Yes I read the summation but also the comments about understanding the variability of mammary cancer/pyrometra by breed. You will recall with the USA Viszla study that the incident rate was surprisingly very low on female Viszlas...


I also wonder what the #1 cause of death is in Sweden; if it is the same as in North America with all cancer being #1?

Didn't want to post but I feel compelled - science is my drug :)


Research does not seek to verify what we want to or wish to believe. Sometimes, truths are not what we thought they were because our truths have been handed down to us from society. Science does not take sides with our collective consciousness.


Emotively, is it true that MOST pet owners are completely unequipped with the knowledge to responsibly deal with an intact animal? I think - yes.


Scientifically, should ALL animals be spayed/neutered because it is good for them? In the absence of owners, I think - No. There is just no way to justify this scientifically. Evolution does not give females mammary glands so that the majority of them suffer from cancer. That would be anathema to reproduction so cannot be the truth, as a whole, applicable to all animals and all breeds.


Stats online are ok as guides but they are by no means complete and they are by no means unbiased. I would use anything I found online with extreme caution. If anyone wants to know how to access 'real' research, they can contact me. Access usually involves a membership to an educational body or a fee.


Pet owners, which include gemy, all make good points here which we should all consider. However, let us begin by admitting that none of us know everything and there is no one-size-fits all approach to all situations. It should not be an 'us and them' debate. Science doesn't have friends.

That's why it is a perfect occupation for me. I'm a loner:cool:

When I lived on the farm I had Bernese Mountain Dogs. Two males and two females, not all at the same time. None were spayed/neutered. The Bernese is prone to Osteosarcoma, and I did not want to increase the risk. I never had a problem. My Sam (my true heart dog) never marked, never tried to roam. Twice a year he did what I called his Tweety Bird. He'd whine and it sounded just like a bird. LOL We did the crate/rotate while the girls were in heat and just didn't have any trouble. The Bernese has a short lifespan anyway, 6-9 years, and I wanted to keep them as long as possible. Sam developed problems with his hips at the age of 5, and died a year later of bloat. The girls started having hip problems at about the same age. George never had a hip problem.
This is a picture of my Sammy.

Hi Gail,

Here are the data for Yorkies from Table 1:

Table 1: Breed, proportion (derived from Cox proportional hazards regression without independent variables) of bitches that developed disease, rank, and numbers of cases in different breeds that by the age of 10 years had developed pyometra (P), mammary tumours (MTs), and either or both of pyometra or MTs.

Breed: Yorkshire Terrier
Pyometra %, (number): 21% (n=157)
Mammary Tumors %, (number): 25% (n=176)
Pyometra or Mammary Tumors %, (number): 39% (n=301)
Total female Yorkshire Terriers in study: 1959

The percentages indicated are quite high in Yorkshire Terriers. I will email you a copy of the whole study so you can read it in greater detail.

I really wish people would take this seriously. I see first hand what happens to yorkies and it is very sad.

Thanks Phil. I will read the PDF tonight. Any comments on its methodology? Has this study been peer-reviewed?

The methodology is quite interesting--it's based on dogs that have health insurance, and the rates of pyometra and mammary tumors are based on the payment of health claims for those two diseases. The article is peer-reviewed. I'll quote some of the more relevant sections below for others to read:

Materials and Methods

The insurance process, benefits and limitations of using insurance data in veterinary research has earlier been described in detail (Egenvall et al. 2000, 2009). The Agria Insurance database contains data from over 260 000 female dogs (≤10 years). In the present study, female dogs enrolled for both veterinary care and life insurance during 1995–2006 were included. Each year a dog was insured contributed to one dog-year at risk (DYAR). All insured bitches were considered at potential risk for developing pyometra. Variables used were: gender, breed, date of birth, dates when dogs entered or left the insurance program, information on the type of insurance for which dogs were enrolled, and whether claims were reimbursed. Breeds were classified according to the Swedish Kennel Club breed classification system. If dogs had reimbursed claims for pyometra, they were considered as pyometra-cases and likewise for MTs. The crude- and breed-specific proportions (percentages) of dogs that had insurance claims for pyometra or MTs up to certain ages (6, 8, and 10 years) were calculated using the base-line survival statement from Cox regression (without independent variables). Incidence rates, crude and breed-specific mean ages were calculated for development of pyometra and MTs and either or both of the two diseases.


...


Results

The database contained data from over 260 000 female dogs, resulting in just over 1 000 000 DYAR calculated for dogs up to 10 years of age. There were 110 breeds with over 1000 DYAR in the database, constituting the basis for the analyses.

...

Discussion

It is common practise to insure dogs in Sweden and approximately 40% of all dogs are covered by Agria Insurance. Approximately 90% (all ages) of the Swedish dog population is intact, hence most dogs are susceptible to reproductive organ disease (Egenvall et al. 1999). The Agria database thus offers unique possibilities for studies concerning such diseases. The incidences of pyometra and MTs have been shown to vary between different breeds, suggesting a genetic background (Egenvall et al. 2001; Rivera et al. 2009). The overall proportion of dogs that had developed pyometra in this study was slightly lower (19%) than previously reported (23–24%) which possibly reflects that more low-risk breeds were included in the present study (Egenvall et al. 2001). Although based on different study periods, the overall proportion of dogs developing MTs in the present study was 13%, which is the same as in a previous report (Egenvall et al. 2005).

...

Elective spaying is commonly performed in many countries, and will prevent development of pyometra, and depending on at which age the surgery is performed, also have a protective effect for MTs (Schneider et al. 1969). However, recently the protective effects by spaying on MT development have been questioned (Beauvais et al. 2012). In the present study, high incidences (up to 73%) of pyometra and MTs were demonstrated in some giant and large breeds of which are commonly affected by post spaying urinary incontinence (Thrusfield et al. 1998). Since the pros and cons of elective spaying will vary by breed, knowledge of breed-variations will be clinically useful in the decision process for each dog.



Due to insurance age limitations, only data from dogs up to 10 years of age are included in the database, which is a study limitation. The true mean ages of diagnosis and incidences are likely to be higher and larger, respectively, and especially in breeds with long life expectancy.

No one is debating science. I could come up with just as many study's and articles to prove spaying and neutering is important and necessary. I think actual life events can count as more then study's that millions of things come into play with. I have seen a rise in poymentra in small dogs many of which did not make it even after the surgery. It's certainly not something I would risk or think anyone else should risk. I can tell you straight from comparing my dog who was spayed before her first heat to a dog who was not that when spayed before there first heat that the mammarys do not develop and you can not get cancer in something you don't have. The rates of cancer in dogs that could be avoided due to spaying and neutering is on the rise because people are being told things that the facts and things are being twisted on. As well as health issues the millions of dogs who are put to sleep every year matter there lives count and matter to!

We'll agree to disagree :) but definitely respect your opinion.

Science proves that cancer is on the rise so not sure how you disagree with that but ok.

It is interesting, the sample population which has been used, and I would argue that there are more limitations than just this...


Additionally, cancer is always going to be found at higher incidence rates as a correlation with age in canines as well as people. Therefore, I'd argue that the diagnosis/incidence rates re: this is a moot point.


It seems like there is a lot of information which is missing. The more I read from this article - the more questions I have...


Interesting all around, though!

Given that insurance companies usually keep quite extensive databases, surely one could have peeled down through the layers, and found out against each breed - when if ever a female was spayed, had she had any litters etc. And why only look at 2 cancers - when you have an abundant wealth of data available to you? I would have loved to seen the rate of hemangiosarcomas and osteosarcomas. As well as ovarian cancers, uterine cancers, bladder, kidney et al.

Also, we cannot generalize on the basis of ONE study. What supporting studies have been made? What contradictory information is there? Are we to assume none? Science doesn't make assumptions. If there is no further data, apart from this one study, then the study is not complete.


That is the nature of science and that is why I would say take the results with a grain of salt i.e. extreme caution.


ALSO, having worked for an insurance company, there needs to be a declaration of BIAS. Of course, it helps to sell policies when studies are generated to increase fear of risk. That is the nature of insurance for risk averse populations. If there is no fear of risk, there is no premium!


I'm done for now - I'm distracted by the smell of chicken dinner.;)

On this bored we may hear a lot about pet insurance but the average owner does not get pet insurance so I don't think that will give you a good accurate number. All cancers have increased in humans for sure but there not being spayed and neutered so that is not the reason. Poymentra is a death sentence period maybe a rare dog makes it but the majority dosent. You can think your dog is fine after surgery and a month later there dead why anyone would take the risk is beyond me. I will never get why when the numbers and science is just not there that anyone could recommend people not get there dogs fixed. This just completly shocks me and makes me a bit sick to my stomach.

I forgot to mention that the study includes data for 110 breeds of dogs for which there were more than 1,000 dog years at risk of data per breed. (Each year a dog was insured contributed to one dog-year at risk). The study included 1,959 female Yorkies, which is a very large number. Yorkies were ranked the 61st most at-risk breed for pyometra (which is mid-range for all breeds studied), 24th most at risk for mammary tumors (which is in the top quartile), and 36th most at risk for developing one or the other (high second quartile). IMHO, based on these data, the rate of pyometra for unspayed Yorkies (21%), the rate of mammary tumors (25%), and the rate of one or the other (39%) provide a compelling reason to spay Yorkies before the first heat, UNLESS they are being used as breeding stock, or have a health issue that would make the risk of spaying too great for a particular individual.

The one limitation that was listed was given as a reason for the real rates of pyometra and mammary tumors may be greater than reported in this study. And as someone else aptly pointed out, you don't have pyometra in spayed dogs at all, and the rate is very, very low for dogs spayed before their first heat since the mammary tissue is largely undeveloped.

I don't mean to be snarky, but I've quoted a lot of the study, and if you are a scientist at an institution with a subscription, you can view the entire article. Or, if you PM me with your email address, I can send you the PDF.

SirTeddy
 

Hope the chicken is good.:)
The more references I read the more confused I am. It does seem that the above mentioned issues are important in intact dogs, but aren't there some health benefits from not neutering? There are pros and cons and we have to look at the whole picture. IDK!!
In the US we do generally neuter, what is the situation in the UK?

Hiya,


I don't believe we have directly communicated before!


Someone else has kindly offered to send me the full study so that I can read it in its entirety, thanks!


Don't worry about offending me! I am not easily offended.


As mentioned before, this is ONE study and as a researcher, I can say that one study would never be used to make a conclusive point in any scientific discipline. The imbalance of information is just ONE limitation of presenting this article and attempting to make generalizations from the information contained within.


I'm a researcher so I'm hardcore when it comes to criticism! I appreciate it, actually. It helps me develop!


Hi Dottie xx


The overall consensus is that it is good to spay and neuter pets due to the shelters which are overpopulated.


Individual advice from vets which I, and others have received, has been that there is no health benefit to intact MALES to be neutered. I have not had any direct advice re: females and I research with lab mice which are never spayed or neutered unless there is something specific under investigation :)

The study cites many references that both support and contradict their results, and discusses them in the discussion section. Of course, the introduction has an extensive review of the literature...

And here is the missing declaration of bias:

Conflicts of interest

None of the authors have any conflicts of interest to declare.




Here is the statement of funding:


Acknowledgements

Agria Pet Insurance kindly allowed us to use their database. Financial support was provided by Thure F. and Karin Forsbergs Research Foundation, M. Forsgrens Research Foundation and Agria Insurance and The Swedish Kennel Club Research Foundation.

BTW, it could be argued that since insurance companies really hate to pay claims unless they have to, that's another reason why these data could under-report the true rates of pyometra and mammary tumors.