Spay-neuter decisions, not so black and white

[Carrie]

We've been conditioned to believe that spaying and neutering our pet dogs is the ONLY way to fly. Here is an interesting report which makes it look like we're darned if we do and darned if we don't. As far as health reasons go, that doesn't seem to be part of the decision for me. Unwanted puppies is. However it is certainly possible to have intact dogs and not produce puppies. That depends on the responsibility of the owner. And perhaps some behavioral reasons. But even those, can be managed just fine. So, this, which I got off another board, is food for thought.


Can We Neuter Cancer in Dogs?
Kevin Hahn, HVM, Ph.D., Dipl. ACVIM
Director of Oncology Services – Gulf Coast Veterinary
Oncology

I spent this past month reviewing studies reported
over the past 30
years regarding the role of hormones and cancer in
dogs.

Do neutering and spaying increase or decrease the risk
of cancer?

Do the procedures alter the prognosis once a pet
develops cancer? How
do hormones cause or prevent cancer?

Uncertainty Factor
I'm still not sure what to recommend to my clients.

There are reports showing that spayed females have
four-time greater
risk for developing cardiac hemangiosarcomas compared
to intact
females. Neutered males also show a significant
increase in risk for
these tumors compared to intact males.

Many of us are familiar with the data that show that
female dogs
spayed before the first heat cycle have half the risk
of mammary
carcinoma of those spayed after the first cycle but
before the second
heat cycle. Dogs spayed after the fifth heat cycle,
or never spayed,
have the highest risk.

Testicular carcinomas in dogs are common, but
neutering eliminates
that risk.

But prostate cancer is actually more common in
castrated dogs then
intact ones. Prostate cancer in dogs is hormonally
independent and
castrated dogs have up to a four-time greater risk of
developing
prostate cancer then intact dogs.

Neutered or spayed dogs have a one-half to threefold
higher risk for
developing bladder tumors and twice the risk of
developing
osteosarcoma as compared to intact dogs.

In on study, males were four times more likely then
females to die
within two years of diagnosis. Male and female dogs
that underwent
gonadectomy before 1 year of age had an approximate
one in four
lifetime risk for osteosarcoma and were significantly
more likely to
develop a tumor then dogs that were sexually intact.


Hormones' Role in Cancer
The possible mechanism by which gonadal hormone
exposure might protect
against or cause the development of tumors in both
males and females
is not known.

Endogenous sex steroids such as estrogen and
testosterone may serve as
prodifferentiation agents that inhibit the malignant
transformation of
cells.

Alternatively, gonadectomized female and male dogs
live longer then
sexually intact dogs, which might be expected to
contribute to a
higher overall cancer incidence associated with
gonadectomy reported
by others.

There are substantial and convincing bodies of
experimental, clinical
and epidemilogic evidence indicating that hormones
play a major role
in the etiology of many cancers.

The underlying mechanism proposed is that neoplasia is
the consequence
of prolonged hormonal stimulation of the particular
target organ, the
normal growth and function of which is controlled by
one or more
steroid or polypeptide hormones.


Genetic Controls
Evidence is mounting to show that the amount of
hormone to which a
tissue is effectively exposed is under strong genetic
control.

Therefore, in addition to external factors such as
diet or exogenous
hormone use, which may modify hormone profiles,
polymorphisms in genes
encoding proteins involved in steroid-hormone
biosynthesis, metabolism
or extra- and intracellular transport and DNA binding
are important
determinants of individual cancer risk.

The major carcinogenic consequence of this hormonal
exposure and the
end organ is cellular proliferation.

The emergence of a malignant phenotype depends on a
series of somatic
mutations that occur during cell division, but the
entire sequence of
genes involved in progression from normal cell to a
particular
malignant phenotype are not known.

Candidate genes include those in the endocrine pathway
as well as DNA
repair genes, tumor suppressor genes and oncogenes.

One explanation of why hormones may initiate cancer
but then the
cancer progresses in a hormone-independent environment
is discussed in
the June issue of Nature Medicine.

Dr. David Feldman found that, because of a mutation,
the stress
hormones cortisone and cortisol can trigger the growth
of later-stage
cancer cells. Feldman and colleagues report that an
androgen-receptor
gene in metastatic cancer cells contains two mutations
that transform
its activity.

Androgens are no longer bound tightly to the receptor.
Instead,
cortisol and cortisone bind and act like
pseudo-androgens, activating
the same metabolic pathways that androgens normally
would trigger.

This means that cancer cells are deluged with signals
to divide, which
could account for their rapid multiplication in
high-grade metastatic
or later-stage cancers.

So do we neuter dogs at an early age to prevent breast
and testicular
cancer but place them at risk for hemangiosarcomas,
osteosarcoma,
bladder or prostate cancer?

Do we monitor cortisol levels in dogs with cancer and
attempt to
reduce these levels in order to improve prognosis?

Unfortunately the answers are not known, but are close
at hand.

With the development of the canine genome map,
investigators are able
to identify loci that predispose dogs to cancer.

My hope is that this will lead to an understanding of
gene regulation
and the role of hormones in cancer initiation and
promotion. Then,
and only then, will we know when it is time to neuter
cancer.


Kevin Hahn, HVM, Ph.D., Dipl. ACVIM
Director of Oncology Services – Gulf Coast Veterinary
Oncology

[shandoggy1]

Wow that was alot of info! I think that at least half of people living with intact animals are irresponsible owners and don't really care if there dog mates and contributes to the overall population of unwanted animals (I'm not talking about show people but pet people and the everyday dog owner). Statistics have shown in the past that intact animals are more likely to roam and get hit by cars than animals that are fixed. We can all assume that we are responsible pet owners but it only takes that one time off the leash to either impregnate a dog or have your dog get hit by a car or attack someone etc. Over the years statistics have also shown that 74% of all dog attacks were caused by unfixed males and that is pretty scary Thus, if these dog owners were "RESPONSIBLE" the percent wouldn't be so high! Yeah, your intact male or female may be okay for the first two years of its life but then low and behold he or she may turn into CUJO with all those hormones behind them . Working in the animal field I have seen alot of mammory and testicular cancers on intact dogs. However, one of my neighbors dogs that was neutered did get prostrate cancer and had to be PTS but he was neutered later in life so that may of had something to do with it. There has been many threads on spaying and neutering and the majority seem to agree that it should be done, however there are a few that seem to be anti-fixing dogs and maybe need more education I do believe that dogs who are intact show higher aggression levels, more dominance, & lack of manners I've seen it to much. I guess there is no clear cut answer to fixing your dog and after reading your info you are Damned if you do and damned if you don't. Me personally will always fix my pets it makes them much nicer to be around and cleaner in your house After growing up with intact male shepards and one intact female who all had some kind of aggression issue I will never keep another intact animal again! Did I RANT enough ! WHEW!

[Hugo]

it is never cut and dry. there are pros and cons with everything. i personally believe that overall the majority of the pet population needs to be altered. i cannot say all owners are this way but there are owners who cannot keep their dogs from roaming and indiscriminantly breeding. puppies are produced, dumped or taken to shelters and the dogs are out again-having more puppies. so of course these should be altered. however, i think that intact animals are fine IF the owners know the risks such as certain cancers, aggression issues, behaviour problems, etc AND the owners choosing NOT to alter CAN and WILL provide training & socialization and go those extra steps to insure the dogs are kept in a way they can not reproduce at will. An owner who just gives in to the hormone rage of the dog and turns him loose or blames his bad behaviour on him being unnuetered and does not provide training to the dog to see that the bad behaviour is resolved is dead wrong.

all of my dogs are altered. i will probably alter any dogs i get in the future. will i alter them early? probably not. more than likely i will wait for the dog to mature. i think the physical growth is compromised somewhat when dogs are altered early. they develop differently. my giant was neutered at 7 months. i wish i had waited til he was at least a year. i believe it would have made a difference in his size, bones, muscular developement. will he suffere in the long run? probably not, but i just wish i would have let him develop a bit. BUT i know how to handle and am responsible with unaltered dogs. i have provided training and socialization (still do) to all my dogs. they are all kept with me and are not allowed to roam. also i think females of large breeds can develope leaky bladder if spayed too early. i know alot of people disagree with this, but i have heard of several large breed owners who have had this happen.

i personally dont agree with the chemical form of birth control in dogs. while i do not know a whole lot about this, i am familiar with birth control (pills, shots, patches, etc) in humans and know there is alot of cancers and other diseases that stem from them. i just dont think that is a safe form of birth control. jmo.
shellie~

[flyndog]

I have to wonder if we would be having spay/neuter conversations if there had been a 30-year-long national campaign in favor of electric fences instead! .

IMO the main purpose of the HSUS, and other national shelter spay/neuter campaigns was to reduce the intake of strays and thereby reduce the cost to taxpayers, in the case of municipal shelters, and to the private sector in the case of privately funded shelters. If that was the purpose, the campaign failed because there sure doesn’t seem like there has been a decrease in the number of intakes at my local shelter. But if the number of dogs taken into shelters has not decreased, the number being euthanized has, or at least it has remained constant thanks to the “no kill” movement.

Most shelters are full of adult dogs. They are not there because of unwanted litters. Most are not strays. These dogs were given up by their owners, either because of lifestyle change or behavior problems. What are the main behavior problems? Aggression and Separation Anxiety. Neutering does not have an effect on either of those, with the exception of a couple of aggression types. Yet aggression, specifically and “better behavior” in general are given as a reason to spay/neuter. Spay/neuter to prevent unwanted dogs, spay/neuter to keep your from roaming, but to spay/neuter as a panacea for behavior problems or for health benefits just isn't valid anymore.

I think maybe a vet who went to school 30 years ago and has not kept up with canine research is more inclined to cling to the belief that it is healthy for animals to be neutered. Early research indicated more prostate cancer in intact dogs. However, 30 years later, we have researchers studying the effects on dogs *for the sake of dogs* as opposed to “fallout knowledge” from some other research of which dogs were merely laboratory subjects. Current research is indicates that first, prostate cancer in dogs is not that common and second, the incidence is higher in altered dogs. There is evidence that testosterone aids in slowing cognitive dysfunction in senior dogs and it is assumed estrogen will have the same effect. There is study hinting that there can be an increase in aggression after altering the dog. Some of that has to do with prenatal androgen "baths" as well as the puppy's placement in the placenta.

Is spay/neuter a good thing? For population control, yes. To prevent unwanted dogs from ending up in shelters, no. To keep our dogs healthier than they would be if as nature intended? I don't think so.

You might be interested in the National Council on Pet Population Study and Policy. Their website is http://petpopulation.org. Not necessarily the same postulates I just put forth.

[Carrie]

Interesting Kit. Yes, I've seen studies about altered dogs possibly being more aggressive because they're lacking that hormone which gives them confidence....(simplified explanation)

Anyhow, on a UK board I use to go on, most of those people were not for s/n unless absolutely necessary. They managed their dogs' behavior fine. It's more about training than anything else. I remember those people talking about the rarity of some of the cancers anyhow, which are suppose to be eliminated by neutering/spaying.

Yes...bottom line is always about business, money or politics isn't it.

[CTDog]

Interesting. Just a couple of notes in response to the first post. Working in two different animal hospitals the past 5 years, I have seen prostate cancer in male dogs. All UNNEUTERED. Just a personal experience.

Also, Insurance companies will tell you that the great majority of dog bites recorded in the United States are by UNNEUTERED male dogs.

Could it be that responsible owners that neuter/spay their pets are also more likely to get diagnosis and treatment for cancer? Could this possibly tip the scales making it look like more of these dogs are getting cancer?

[Carrie]

I think that we're conditioned/brainwashed into thinking that only responsible owners n/s their animals and that only people who s/n their animals are responsible. I don't think it's necessarily so. I know lots of people who's animals are s/n and they're very irresponsible in other ways. I also know that many, many people have intact dogs and are very responsible with their dogs.
Perhaps statistics discount that.

As far as aggression issues or dog bites, there are sooooo many types of aggression and reasons that I don't see how a blanket statistic stating that more bites are done by intact dogs proves anything. That is not a true experiement or study. What about all the other factors that come into play? Did they rule those out and eliminate them? What if an intact dog had an injury and someone grabbed at it? What if an intact dog didn't have good training or a good leader? Now they blame on the fact that it was not neutered. You can't know that that is the reason. You see what I'm saying? Some of these statistics you have to take with a grain of salt.

[CTDog]

Originally Posted by Carrie

As far as aggression issues or dog bites, there are sooooo many types of aggression and reasons that I don't see how a blanket statistic stating that more bites are done by intact dogs proves anything. That is not a true experiement or study. What about all the other factors that come into play? Did they rule those out and eliminate them? What if an intact dog had an injury and someone grabbed at it? What if an intact dog didn't have good training or a good leader? Now they blame on the fact that it was not neutered. You can't know that that is the reason. You see what I'm saying? Some of these statistics you have to take with a grain of salt.

I don't doubt that there are some responsible owners with intact dogs. Take the show people for instance. However, I still think they they are few and far between. Some statistics should not be discounted. If it is shown more unneutered male dogs are biting does it matter if it is because the dogs are more aggressive or that irresponsible owners own them? They pretty much go hand in hand. Something is wrong regardless.

My main concern with letting people think that not neutering your pets is o.k. is the ever increasing pet overpopulation in most countries including the one I live in. When I go to petfinder and see hundreds of beautiful dogs gassed in gas chambers weekly, it makes me sick. Pet overpopulation is a huge problem.

I guess my point is...you are clearly a responsible owner that has an unneutered dog. That is great. However, it is clear (to me anyway)that the majority of people that keep intact pets are not responsible. Otherwise this mass killing would not be occuring. I think it is in the best interest of most involved if people are STILL encouraged to spay/neuter their pet. We simply cannot afford to have even one more accidental "whoops" breeding occur until we solve our present situation.

[shandoggy1]

Well said CT! it is exactly what I would have said Here in Boston where I live we had a bad summer of pitbull attacks a couple of years ago. All those dogs were intact 4 male and 1 female. Not one of these incidences was provoked they were just dogs that were out loose and had done damage to people and children that happened to come across them wrong place at the wrong time. A neighbor of mine had a male shepard imported over from Germany and the he was left intact by the husband just because Anyways, one day when the wife was home cooking in the kitchen the dog went up to her growling and backed her into a corner he then proceeded to bite her in the leg. That wasn't a provoked incident. Luckily the husband was home and got the dog away from her. They still kept Fritz but at the age of 4yrs one of the first things to go was his testicles and then some intense training. He has since adjusted his attitude problem and is fine. In my experience with unaltered males I have seen to many problems with them and it is my opinion that they should all be fixed if pets!

[elegy]

Originally Posted by flyndog

Most shelters are full of adult dogs. They are not there because of unwanted litters. Most are not strays. These dogs were given up by their owners, either because of lifestyle change or behavior problems. What are the main behavior problems? Aggression and Separation Anxiety. Neutering does not have an effect on either of those, with the exception of a couple of aggression types. Yet aggression, specifically and “better behavior” in general are given as a reason to spay/neuter. Spay/neuter to prevent unwanted dogs, spay/neuter to keep your from roaming, but to spay/neuter as a panacea for behavior problems or for health benefits just isn't valid anymore.

true it's not litters of pups who end up in the shelter most often, but those adult dogs all started out as pups, and how many of those pups were impulse purchases? how many of those pups were the result of oops litters and make-a-quick-buck litters? how many of those pups wouldn't have been bought only to be dumped if the people had to put forth a little bit of effort and wait their way through a responsible breeder's waiting list?

and while i agree that speutering is not a panacea for behavior problems, i do believe that we'd have a lot fewer behavior problems in dogs if the unstable, fearful, aggressive, unsound dogs that are being bred by accident or to make a buck had been speutered. i personally believe that a lot of the behavior problems that we have today are the result of crappy breeding and crappy genetics and these extra-needy dogs being sold to anybody who can fork over the money for a cute puppy.

so i'm sorry, i believe an assertively pro-speutering stance is what is needed in the united states right now.

[flyndog]

There has been a pro-speutering stance in the US since the 70's!

According to numbers provided to the HSUS , a whopping 72% of the 65 million owned dogs are spayed or neutered, yet the shelters are still full of unwanted dogs. Most are mixed breeds, not purebreds. The majority of owned dogs are male (hold that thought).

Record after record of dog bite stats point out that the commonalities in aggressive biting dogs are a lack training and irresponsible, uneducated, or inattentive owners. In the latest (post-pitbull) Denver study, most were AKC registered purebreds, yet not current in license or vaccines. The majority of aggressive biting dogs are intact males. It is unlikely that all bite victims know a dog’s age and sexual status, but even though the stats are flawed, they’re all we’ve got.

If about 25% of the dogs in the US are intact males, it must be a very small minority of irresponsible and uneducated owners who own intact aggressive biting males. Most of those biters are undertrained and undersocialized dogs, and chained outdoors, loose or otherwise uncontrolled. The outcome would undoubtedly have been the same whether the dog was intact or not.

CT, I think you make a very good point about neutered dogs and prostate cancer. If it is the responsible, educated, and caring owner who brings her neutered dog in for routine checkups then, statistically anyway, a higher incidence of cancer would be seen in those dogs. I guess it pays to see who is funding the studies we read. I understand that James Serpell spoke about some of this at the APDT conference last month, and I think it was based on some info distilled from his C-BARQs (Canine Behavior and Research Questionairre). I haven’t gotten my hands on anything yet.

I’d like to say it was for more noble reasons, but I’ve altered my last few dogs for the purely selfish reason that I don’t want to deal with the hassle of hormones - in any form.

[Leon]

Is there scientific proof that testosterone in dogs causes aggression towards humans? Where I live almost noone neuters their males, yet I've never met a human aggressive dog.

[Kade]

I'm sure there are quite a lot of responsible dog owners with intact dogs. But overall, the dogs causing overpopulation problems are those owned by people who do not care enough about the problem to alter their dogs or contain them.

Of course the number of dogs in shelters has grown over time -- dogs multiply exponentially and quickly (far more quickly than the number of responsible dog-owning households has grown). Who is to say how many more dogs would be in shelters and/or euthanized and/or roaming the streets stray if we had not been spaying/neutering all these years?

I agree that there are other factors in place regarding adult dogs ending up in shelters (the breakdown of the "somebody's always home" family plays a big part, IMO), but the existence of more dogs is undoubtedly caused by intact dogs owned by irresponsible people.

The way I see it, you blanket dog owners with a "spay/neuter" campaign to the point of brainwashing, and the ones who do their research and decide against it will do their own thing. In the meantime, you hope you just succeed in brainwashing those who are willing to go with the crowd. If you start using a "neutering isn't necessarily best" argument for the general public, then these same people (who are unwilling to think for themselves) think, "Hmm, I don't have to neuter my dog!" and don't do it. And then we end up with a far, far worse overpopulation problem.

[CTDog]

Originally Posted by Leon

Is there scientific proof that testosterone in dogs causes aggression towards humans? Where I live almost noone neuters their males, yet I've never met a human aggressive dog.

I meet them all the time at work. Granted a hospital setting is not the best place for a dog...most hate the vets. However, this large unneutered mastiff mix wanted to rip my face off today the second I touched his back end to get him on the scale to be weighed. It seems like these really aggressive dogs I meet are usually unneutered.

I know not all unneutered dogs are aggressive (my parents inherited a very nice unneutered dog that later developed prostate cancer but that's a whole other story) but they certainly seem to have a propensity for it.