Friday, March 16, 2007
Subject: early spay and mammary cancer
So here are the 'facts' on spaying early in regards to mammary cancer.
Spaying before 1st heat cycle reduces mammary cancer by over 99%.
However, spaying after only 1 heat cycle reduces mammary cancer by about 70% (depending on what study you read). Spaying after 2 reduces incidency by 25 %, and spaying after 2 or 3 cycles has no effect on incidence of mammary cancer.
Having said that, overall incidence of mammary cancer is estimated at 0.2% in the whole population. It is the most common cancer in female dogs, but in dogs, 50% are benign. Average age for onset of mammary tumors is 10-12 years old (so keep this in mind when advising swissy owners).
Additionally, one recent study has shown that early spay increases the incidence of lymphoma (can't find the paper to say exactly how much though, sorry). So as long as they spay before 2nd heat cycle I think waiting is totally reasonable. They still get a major protective effect, and incidence only goes up to 0.3%. I have removed 3 mammary cancers in the last year, all of which were dogs under 40 pounds. 2 were benign, the other was not but good prognosis since it was removed early. I see females every week with 'juvenile vulva' syndrome...recurrent UTI's and major issues. If not spaying your dog early was a death sentence via mammary cancer, my bitch would have been spayed long before now. My bitch is only 3 and each month when I give her heartworm preventive I roll her over and examine her... its just part of our routine. As long as puppy people know there are 2 sides to it...there's no reason why they can't make this decision (with your help). Obviously I am not a
big fan of hard and fast "rules" on how to treat a dog, when there are many factors that go into any medical decision. Having a large breed dog means you have increased risk of bone cancer, bloat, splenic tumors, etc etc. But you don't get a small breed dog because they have increased incidence of dental issues, endocardiosis, diabetes, patella luxation, etc etc. Males get prostatic problems and perianal tumors. Females get mammary tumors and pyometra....In order to avoid all predisposing problems, get a CAT for goodness sakes (they have issues too, surprise surprise). You can go on and on about how the genetics of any dog will predispose them to one problem or another, but you CANNOT make a decision on any one factor! GRRR! If your dog gets a mammary tumor, you have it removed ASAP...just like if they got a mast cell tumor you'd remove that ASAP. If any vet on the planet could predict what will happen to a dog and what they'll die from and at what age...they'd be a
Sorry about that, just a rant from one vet who thinks that many other vets have let pet overpopulation problems give them tunnel vision. I obviously have strong opinions on the subject, feel free to forward this to any puppy people being given a hard time.
Rebecca Martin (the DVM with an intact bitch, despite having been ridiculed many times by other vets for it, and even nicknamed the 'dog pimp' by a radiologist in vet school)
Subject: Re: early spay and mammary cancer
So i am not a veterinarian but have enjoyed Swissys in our family since
1988. Having been advised by Gretel Summons early on NOT to spay before the bitch
was 15 months old., preferably 24 months---also NOT to neuter a male before
18 months, preferably 24 moths. All this for two good reasons :
the females will almost always be incontinent when spayed before their
hormones are balanced and the males will likely not have majestic heads if
neutered before their hormones are established.
If i have a dog that does not pass health clearances, it is spayed or
neutered but that is after the 24 month time period. Otherwise, i spay and neuter
at 6 or 7 yrs, both sexes. No incontinent girls in all these years , and no
incidences of mammary cancer.
When we do raise a litter we advise all families taking a Swissy home, to
abide by the same advice we got from Gretel. We have a wonderful relationship
with our vets--we discuss advice and opinions and experiences and the
conclusion is : if it isn't broken, don't need to fix it. So we keep on the path
that offers the smoothest healthiest ground for our Swissys.
We once purchased a lovely English Springer who had been spayed at 7
months: she had mammary cancer 8 times in the 13 years she lived. Don't want to
even think about the odds on that.
Spaying and Neutering
It is imperative that you do not spay your female GSMD before she is a minimum of 12 months old. GSMD that are spayed at any early age seem to have a great tendency towards incontinence. It is preferable to wait until she has gone through a heat cycle. I realize that there will be some inconvenience related to letting her go through a heat cycle, but GSMD that have gone through a heat cycle seem to be much less prone to incontinence than those who have not. Many “pet” vets will try to convince you that it is in your puppy’s best interest to spay earlier. It is true that dogs that go through a heat cycle have a slightly increased risk of mammary tumors (maybe 5%). It is also true that a Swissy spayed at a young age may be as much as 40% more likely to develop incontinence. It is up to you to weigh the risk. It is not your vet who will be living with a 100 lb dog that leaks urine. The truth be known, most vets want to spay at an early age because it is much easier surgery. You need to stand your ground on this issue.
Males are not affected with the incontinence issue, but you may want to wait until your male is 12 months or older as well. Males that are neutered earlier tend towards excessive long bone growth and tend to end up slightly “bitchy” looking. Swissys are very slow maturing and waiting until a year old does not have any ill effects.