Q: We have just added a golden retriever puppy to the family. She is 4 months old and our veterinarian has discussed the benefit of spaying her before she goes into heat to reduce the chance that she will get mammary cancer.
I have been told by our breeder to wait until after she has gone into heat a couple of times so she can mature normally. What do you recommend?
A: Let me begin by stating that I (Henri Bianucci) firmly advocate that all dogs and cats, which are not specifically intended to breed, should be sterilized. In the traditional sense, that means neutering. More specifically, it means castrating the males and at least removing the ovaries of the females.
However, we are beginning to understand the health benefits conferred by gonadal hormones and the possible consequences of their removal. This growing body of knowledge has sparked an interest in sterilization procedures that allow retention of the gonads, which is commonly referred to as tubal ligation and vasectomy.
A few years ago, requesting such a procedure for a dog or a cat would have been reserved for “kooks." But as in so many other instances, science has caught up and proven that the “kooks” may just have a point.
Prevention of mammary cancer is the most frequently cited reason for spaying a dog before it reaches sexual maturity. This is still generally believed to be true, but a recent comprehensive evaluation of published studies on the topic found that the linkage may not be as strong as some suggest. A more recent study, looking specifically at Labrador and golden retrievers, found no difference between intact and spayed females with regards to mammary cancer.
Another study found that rather than reducing the incidence of prostatic cancer, neutering actually increased it. Osteosarcoma (bone cancer) was twice as likely to develop in certain breeds when neutered, and in Rottweilers neutered before a year of age, there was a three- to four-fold increased incidence when compared to intact dogs. A study from a database of more than 40,000 dogs found that neutered male and female dogs were more likely to die of cancer than intact dogs.
There are breed and sex differences in vulnerability to various cancers. For instance, a recent study compared the effect of neutering on the development of the cancer types hemangiosarcoma, mast cell tumor and lymphosarcoma between golden and Labrador retrievers.
They found that neutering at any age had little effect on the development of cancers in male and female Labs and male goldens. One notable exception was that early neutering increased the incidence of lymphosarcoma in male goldens. Conversely, neutering had a profound effect on the development of cancer in female goldens. This study also found that the age at which a dog was neutered influenced the effect it had on various cancer types.
The development of joint disorders also appears to be strongly influenced in certain breeds and sexes by neutering at an early age. For instance, early neutering had no effect on the formation of hip dysplasia in female goldens, but doubled the rate of development in male goldens.
Further comparisons found that early neutering in Labs and goldens significantly affected both breeds. Early neutering doubled the odds of having one or more joint diseases in goldens, and it increased the odds by five times in Labs. Interestingly, male goldens became more likely to develop cruciate ligament injuries and hip dysplasia, while male Labs increased their odds of cruciate injuries and elbow dysplasia.
From the standpoint of orthopedic disease and cancer development, research is indicating that certain breeds and sexes demonstrate varying vulnerabilities to devastating cancers and orthopedic diseases, which may be influenced by gonadal hormones. These hormones influence skeletal development and may confer protection against certain cancers. More research is needed to establish breed- and sex-specific recommendations about the timing of neutering or the decision to pursue alternate means of sterilization.
It is worth mentioning that neutering is also a means of controlling certain secondary sex behavior traits such as roaming, mounting and aggression in males. In females, spaying abolishes heat cycles, which can be messy and draw the attention of male dogs.
If tubal ligation or vasectomy were chosen, these issues would remain. Conversely, some dog owners have complained that their dogs have become overweight and lazy after neutering. For the small number of patients for which this is an issue, this would be avoided.
To recap: The influence of neutering on the development of cancer and orthopedic disease varies between different breeds and sexes. It also varies with the age at which it is performed. All pet dogs and cats should be sterilized, but the recommended method and timing of this may be guided by breed and sex, as related to certain disease vulnerabilities.
As for your dog, spaying later (after 6 months) may predispose her to hemangiosarcoma, one of the most common fatal cancers in goldens. Spaying early (before 6 months) may double the odds of joint disorders and still increase the odds of other cancers.
Taking a conventional tack, I would spay this one before 6 months. Alternatively, an emerging body of evidence may support a tubal ligation in this particular bred and sex.