THE SCIENTIFICALLY PROVEN NEGATIVE SIDE EFFECTS OF DOG NEUTERING BEFORE SEXUALLY MATURE
The early neutering of dogs is not without it’s side effects or critics, and I’m certainly one of them. But please, before the heavily stressed and over-worked shelter staff post up about overpopulation problems (I spent a couple of years in them too), lets look at this issue with less emotion and more science.
It is well documented in the literature that by removing the gonads in developing animals you certainly prevent the possible occurrence of gonadal cancers such as various forms of testicular, prostate and ovarian cysts and cancer. I think that goes that without saying. If you have no prostate you’re not going to get prostate cancer. I think we’re clear on that one.
But if ignore the fact that gonadal and mammary cancers are rare enough in the general dog population, dogs are known to recover very well from testicular cancer following diagnosis and castration, Furthermore while between 30-50% of mammary cancers are malignant in dogs and, when caught and surgically removed early the prognosis is very good in dogs (Brodey et al. 1983, Meuten 2002).
Also, while these possible cancers of your pet will be avoided, numerous studies show that removing the sex organs early in the developmental period of an animal causes cancer in your pet, just not in their testes or ovaries.
A study in the Journal of Veterinary Internal Medicine, compiled over 13 years found that “… neutering dogs appeared to increase the risk of cardiac tumour in both sexes”. The results showed that spayed females were five times more likely to suffer tumours of the heart than intact females (Ware and Hopper 1999), one of the three most common cancers in dogs today.
In another study spanning 14 years of research and involving 3062 purebred dogs with osteosarcoma compared to 3959 purebred dogs without osteosarcoma, it was concluded that sterilisation increased the risk for bone cancer in large breed purebreds twofold (Ru et al. 1998).
Upon further investigation using 683 male and female Rottweilers spayed or neutered before one year of age, both sexes were found to be significantly more likely to develop bone cancer than intact dogs with early sterilisation bestowing a staggering 25% likelihood of bone cancer in your Rottweiler (Cooley et al. 2002).
In a study of 759 intact and neutered golden retrievers Torres de la Riva et al. (2013) and found significant issues associated in neutered dogs. Almost 10 percent of early-neutered males were diagnosed with lymphosarcoma, 3 times more than intact males.
It’s often stated that neutering a male dog will prevent prostate cancer but some authors refute this on the basis that “ non-testicular androgens exert a significant influence on the canine prostate”. The College of Veterinary Medicine at Michigan State University found “…castration at any age showed no sparing effect on the risk of development of prostate cancer in the dog“.
All these considered, it’s hard to argue the cancer benefits to neutering early or you end up playing the whole “I see your very slight chance of testicular cancer and raise you a certain increase in bone and heart tumours”.
Early Neutered Dogs Live Shorter Lives
Waters et al. (2009) found that neutering female Rottweilers before four years of age reduces life expectancy by 30%. Females that kept their ovaries the longest were nine times more likely to achieve exceptional longevity (13+ years).
The lead author of the study notes:
WHAT DO THE SEX HORMONES DO IN DOGS?
While sex hormones in males and females function primarily in the whole “sex” business from conception to baby birth, they also play pivotal roles in the maintenance of body muscle and bone growth.
Testosterone: Testosterone’s dramatic effects can be clearly seen in lanky 13-year-old males. It controls all the typical puberty bits in males such as the growth of the adam’s apple, facial and body hair to the height and muscle mass of the individual. Adults testosterone continues to function in maintaining muscle strength and mass, and it promotes healthy bone density, as well as reducing body fat (one reason why spayed pets can put on weight).
Oestrogen: Oestrogen too, functions in skeletal growth. At puberty, oestrogen promotes skeletal maturation and the gradual, progressive closure of the epiphyseal growth plate (plates of cartilage at the end of bones, which are responsible for laying down new bone). Oestrogen also functions in maintaining the mineral acquisition of the bones.
Female dog neutering or ‘spaying’ a female animal involves removing the womb and ovaries (an ovaro-hysterectomy). Males are castrated whereby the testicles are surgically removed. This is done before dogs come into puberty (i.e. start producing sex hormones for the first time) which is very approximately 6 months in males and around 9 months in females, though breed and body size play large rolls here. General advice from the majority of veterinary circles is that responsible dog owners neuter at 6m months. In other countries, it is much earlier. Both operations are carried out under general aesthetic.
The number one reason for removing the sex hormones is to prevent unwanted breeding, hence those on the front line of mopping up all our unwanted pups are very big fans. The major health benefit constantly cited is to prevent the possible occurrence of testicular cancer, perianal cancers and ovarian cancers in dogs and cats. Other reasons often cited is the spread of inferior genetic traits and to reduce problematic behaviour including male-male aggression around females in heat and the roaming behaviour of both males and females when love is in the air.