Whether to spay or neuter a dog is always a “passionate” topic. In South Africa, we have a large population of dogs that remain free to roam unsupervised. This is a very real problem.
For this reason, this article is specifically aimed at responsible pet owners, and owners of working, active and sports dogs (our favourite kind of people). Being a responsible pet owner is a very important part of the equation.
The act of spay/neutering a dog has potential long-term health risks associated with it. This is especially true when done in a young dog, and so is worthy of discussion.
That isn’t to say that dogs shouldn’t be spayed or neutered. That is a personal decision best left to the pet owner.
Much time is spent discussing why you should spay or neuter your dog, but very little time is spent talking about why you shouldn’t.
The goal of this article is to give you some of that information so you can make the best decision for your dog.
Significant research indicates that spay/neuter and joint disease may be related. This surgery has the unfortunate capability of permanently changing a healthy puppy joint into an unhealthy one. The following must be considered:
At the heart of the matter is how spay/neuter affects the dog’s hormones.
When a dog’s reproductive organs are removed, the sex hormones they produce also disappear. Sex hormones are responsible for more than just sexual behaviours. One of their responsibilities is regulating growth.
Breeders can readily spot the difference between an intact dog and a neutered dog. Neutered dogs have longer limbs, narrower heads and bodies, and they are lighter in bone. When the sex hormones are removed, the growth hormones missing important regulatory inputs. This causes the bones to continue to grow longer than they ought to. Studies have proven this true (Salmeri et al, JAVMA 1991).
In each long bone, there is a growth (epiphyseal) plate, which is a band of cartilage found near the joint. This growth plate lays down bone as a puppy develops. As it builds bone, the bone becomes longer and the puppy gets larger and taller. Once maturity is reached, this growth plate starts to close and turns into bone. The puppy has now reached his full height.
When dogs are sterilized before maturity, the closure of some, but not all, growth plates may be delayed. This would be especially true if a dog is sterilized when only some of his growth plates are closed. Various growth plates close from the time a puppy is 8 weeks to the age of 24 months.
The dog’s elbow and stifle (knee) joints are similarly designed. Above each joint is one bone (humerus and femur respectively). Below are two bones (in the elbow there is the radius and ulna and in the stifle, there is the tibia and fibula). One bone effectively sits on two.
Consider what would happen if one of those bones below the joint stopped growing before the other bone and they ended up being different lengths?
It would be similar to building a house on a slope. The weight of the home wouldn’t be evenly distributed. There would be increased load at the lowermost corner of the house.
The same situation could present in the elbow and stifle joint when the closure of the growth plates is artificially delayed. This could lead to an uneven load on the joints. Uneven load increases the risk of both elbow dysplasia and cranial cruciate ligament tears.
Research found that spayed and neutered dogs were twice as likely to suffer cranial cruciate ligament rupture. Whitehair et al (JAVMA Oct 1993) and Slauterbeck et al also found an increased risk (Clin Orthop Relat Res Dec 2004).
“…if the femur has achieved its genetically determined normal length at eight months when a dog gets spayed or neutered, but the tibia, which normally stops growing at 12 to 14 months of age continues to grow, then an abnormal angle may develop at the stifle.
In addition, with the extra growth, the lower leg below the stifle likely becomes heavier (because it is longer), and may cause increased stresses on the cranial cruciate ligament.”
~ Chris Zinc DVM PhD DACVP
Additionally, sterilization can cause a loss of bone mass (Martin et al, Bone 1987), and obesity (Edney et al, Vet Rec Apr 1986). An overweight dog with lighter bone mass may lead to an increased risk of cranial cruciate ligament tear.
It was also found that spayed/neutered dogs are three times more likely to suffer from patellar luxation (Vidoni et al, Wien Tierartztl Mschr 2005).
The thought of hip dysplasia is enough to strike fear into any large breed dog lover. For that reason, the bulk of research on spay/neuter and joint disease is focused on this disorder.
Dogs sterilized before the age of six months have a 70% increased risk of developing hip dysplasia.
“it is possible that the increase in bone length that results from early-age gonadectomy results in changes in joint conformation, which could lead to a diagnosis of hip dysplasia.”
~ authors of this study (Spain et al, JAVMA 2004)
More evidence that spay/neuter can increase the risk of hip dysplasia. Van Hagen et al (Am J Vet Res, Feb 2005), found that of the sample dogs diagnosed with hip dysplasia, those that were neutered six months prior to the diagnosis were nearly twice as likely to develop hip dysplasia.
A study by Dannuccia et al (Calcif Tissue Int, 1986), found that removing the ovaries of Beagles caused increased remodelling of the pelvic bone. This also suggests an increased risk of hip dysplasia with sterilization.
Although not technically a joint issue, osteosarcoma is a cancer of the bone. This bears mentioning because spayed and neutered dogs are twice as likely to develop this deadly disease (Ru et al, Vet J, Jul 1998).
In another study, male Rottweilers, a breed susceptible to osteosarcoma, were nearly four times more likely to develop osteosarcoma than intact dogs (Cooley et al, Cancer Epidemiol Biomarkers Prev, Nov 2002). In fact, Rottweilers spayed or neutered before one year of age had a 28.4% (males) and 25.1% (females) risk of developing osteosarcoma. Researchers concluded from results that the longer the dogs were exposed to sex hormones, the lower their risk of osteosarcoma.
Of course every surgery and anaesthetic carries its own risks. There are other related risks with spay/neuter. These may include increased risk of certain cancers, hypothyroidism, urogenital disorders, cognitive impairment, obesity among others. All should be considered when deciding on spay/neuter.
What does seem clear, however, is that the increased risk of joint disease if the dog is sterilized before the growth plates close.
It’s important to remember that the sex hormones do play a synergistic role in your dog’s growth and development. The removal of these sex hormones will create an imbalance in the body.
The fallout from this imbalance remains to be seen. Research into the effects of sterilization is in its infancy, even though hysterectomies on humans and spay/neuter on dogs have been accepted as a normal procedure for decades.
The age at which the growth plates close is dependent on the dog and the breed. Generally, the larger the dog, the later the growth plates will close. In giant breeds, this could be nearly two years of age.
It is impossible to guarantee that a puppy will have healthy joints if they are spayed/neutered at an early, especially before the age of two.
Whether the puppy’s family decides to keep their dog intact or sterilize him after that age is entirely up to the family. This requires responsible pet ownership and people who are willing to be accountable for their pets.
People involved in rescues and shelters may have a different view on this and understandably, they are entitled to it.
When considering spay/neuter, it’s important to make a decision based on facts. Try to steer clear of an emotional response that may affect the health and longevity of your dog.
It’s not for me or anyone to dictate what you should do with your dog.
The good news is that there are alternatives to the complete removal of the sexual organs.
Vets are starting to do vasectomies and tubal ligations. These procedures are becoming more popular with less interference with the sex hormones. Your dog keeps his reproductive organs right where nature intended them to be.
It’s your choice in whether and when your dog is spayed or neutered. How important it is to you that his/her sexual organs and hormones remain in place is also up to you.
However, once your dog is spayed or neutered, you can’t reverse your decision. So dig a little deeper and you might find a solution suits both you and your dog for an long health and happy life.
Excerpts were taken from an article by Dana Scott, Editor In Chief for Dogs Naturally Magazine and breeder of Labrador Retrievers under the Fallriver prefix.
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