I am reliably informed that present day research shows that young bitches spayed before the first season are 0.5% LESS likely to contract breast/mammary cancer.  This is of course contrary to previous advice of going through first season and then spaying.
Any thoughts on this ?

It seems logical that if you remove oestrogen you are likely to have a lot less oestrogen generated cancers but it is very hard to comment on the evidence without seeing it and being to evaluate it properly.

Yes I quite agree with that and have now had a few bitches spayed of various breeds before first season and they have grown into the most beautiful loving family pets.
I have also over the years had bitches left entire out of those there has been 1 incontinent and lost one to pyo and had 2 others who got pyo and had to be spayed later in life.  I've also spayed at various older ages and one bitch I had spayed after her second season I lost aged 4 years old to mammory tumours.
The best and healthiest girls were spayed at 6 months of age.

Actually that is old and flawed research shown to have been on an un-representative sample of bitches.

Some breeds rarely get mammary tumours yet others invariably do.  Of course of the ones that do less than 50%are malignant, and if removed early eminently treatable.

Out of Five entire bitches that I ahve owned above three years of age, only one had mammary tumours.  Pea size lump removed at 5 1/2 (and spayed soon after) and another found in same spot so partial mastectomy performed at 8 1/2.  She lived to 13 1/2 and did not die of any cancer.

The others are between age 3 and 9 1/2 with another having lived to 11.

I dont know much about bitches (having always had dogs) but the ones I do know have noticeably matured considerably after a season, so is it fair to neuter a bitch before a season ?

My parents have their first bitch and after her season my dad said how much of a "little lady" she has become - and its true :rolleyes:

I have one bitch that I spayed early -4 ½ months -and I never will again as she has never matured and has stayed very shy and has no confidence -nothing at all like later pups (entire) from same mum. She's 5 now.

I will try to find the research, having read it a couple of years ago now.

In googling I have found it interesting that msot bitches don't get Mamamry tumours until over 8 years old and most commonly after 10.

Now here's a point: can't there be a genetic cause for mammary tumours? Certainly there is a strong genetic element in humans, mice and rats, that I do know.

Found a fair few references to higher numbers in cocker's,a nd dachs and some other breeds.

This article and references shows some of the cons of EARLY neutering. http://www.shershihtzus.com/id150.htm but am still finding trouble finding the article/study that contradicts the commonly held belief for the protective effect for bitches re mammary tumours.

Here's another article hope you find this interesting

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

I have a nasty suspicion that the main reason for the drive for peopel to spay and neuter is population control, as the Vets et al do not trust (with good reason in USA it would seem especially) for people to act responsibley with entire animals.

With this view firmly in mind they have done research to try and shwo the benefits to the animal and the owner rather than society in general, as after all generally the owner will be paying a not inconsiderable amount for thsi perceived benefit.

The real reason is that there are two may cats and dogs irresponsibly owned and reproduced.

Unfoirtunately those most likely to neuter are thsoe who probably don't need to.

I think there may well be a genetic component but that does not mean there is no benefit to removing potential risk elements although it does mean those most likely to benefit from doing so can be identified.

My thoughts are that 0.5% LESS likely (not even a whole 1% less likely) isn't a good enough percentage to spay before the first season and not allow the bitch to mature.

I think the figures quote are 3 to 7 times less likely to develop mammary tumours with the incidence being perhaps as low as 05%.

On the advice of our vet, we had our Bernese bitch spayed before her first season (at around 7 months) for this reason particularly as Bernese are very prone to cancers, it didn't seem to affect her maturity at all, her coat didn't go fluffy and she is anything but shy. Again on the advice of our vet, our Gordon was left to have 2 seasons to allow her to develop her coat properly, she had no problems either but I can't say that I see her as any more or less mature than the Bernese. Maybe it simply depends on the bitch involved, but if you are not intending to breed and you are advised that cancer may be an issue with the breed then I think it is worth thinking about.

There is good evidence especailly for large breeds prone to boen cancers that neutering increases the risks.

This document gives the pros and cons very fairly.http://www.naiaonline.org/pdfs/LongTermHealthEffectsOfSpayNeuterInDogs.pdf

Good document Brainless, but it also states that "Mammary tumors are by far the most common tumors in intact female dogs, constituting some 53% of all
malignant tumors in female dogs" and also that Bernese are a high risk breed for pyometra, so you pays your money and you takes your choice really :-) . All we can hope is that we have lessened the risk somewhat for our girl. 

Yep that is true.

Basically seems to be a balancing act between pros and cons, but of course the pro's only relate to Pyo for breeders as the mammary tumour risk is inherent if you are to breed the next generation.

Does seem though that for males if it ain't broke don't fix it.

Also the malignancy isn't such an issue in mammary tumours as in others as detected early the prognosis for cure is very good.

Most bitches don't develop Mammary tumours until 8 to 10 years old (sadly an age many of your breed rarely reach) and are easily dealt with when small, unlike some of the other cancers.

The only cancers spaying is helpful in is mammary, but it increases the risks of bone caner, hypothyroidism is three times more likely etc.  As the survival rate is far better for mammary tumours than bone cancer it is on balance better to delay spaying in larger breeds especially those prone to these cancers.

Actually, there is only thought to be an increase based on a study of Rottweilers which are very prone to osteosarcoma. The author of the article does not state her credentials for writing it and only has one reference to the incidence of Osteosarcoma in her bibliography.
I also found this written by a vet on another site and referring to the same article you posted:

"They were testing a hypothesis that there MAY be a hormonal link to the development of bone cancer in Rotties because Rotties get bone cancer a lot. So they looked at a group 683 Rotties that had been spayed or neutered before 1 year of age to see if they MAY have a higher risk of bone cancer. They found that "Male and female dogs that underwent gonadectomy before 1 year of age had an approximate one in four lifetime risk for bone sarcoma and were significantly more likely to develop bone sarcoma than dogs that were sexually intact." BUT they also said that "We conclude that the subset of Rottweiler dogs that undergo early gonadectomy represent a unique, highly accessible target population to further study the gene:environment interactions that determine bone sarcoma risk and to test whether interventions can inhibit the spontaneous development of bone sarcoma."

So there is NO proof of cause and effect here. They only say that THIS particular subset of Rotties is a good population for testing to see IF any hormonal link really exists. "

As I said before - you pays your money.... :-)

My little girl is booked in for spaying tomorrow and I am dreading it. We only decided to have her spayed because our older dog had mammary tumours at 4 and went on to have a further 4 operations over the next 5 years.. But I really don't like send a healthy dog to the vet and even at this late stage, I'm not sure I want her spayed and I am so worried that something may go wrong.