Dogs' surgical sterilization is the action of disabling the animal's reproductive functions by removing their gonads.
- For the male, the testicles have to be removed, whereas,
- for the female, the ovaries can be removed alone (oophorectomy), or with the uterus (ovario-hysterectomy).
This process is a routine intervention in a veterinary clinic. The fact that this practice is common can sometimes the veterinarian to think, incorrectly, that the guardians have a full knowledge of the advantages and disadvantages of this procedure.
The goal of this article is to raise awareness about the advantages and disadvantages of surgical sterilization for both sexes. We will also tackle the matter of recommended age for such an intervention and, finally, we will mention the alternatives to the entire surgical sterilization.
The advantages of surgical sterilization
- Advantages for both sexes - The main advantage of surgical sterilization is preventing the birth of unwanted puppies. This is the main reason for guardians to have their pets sterilized [Hill et al., 2011]. In the big picture, reducing the number of unplanned births allows limiting the risk of abandonment, which is why surgical sterilization is usually promoted by animal welfares associations [Hill et al., 2011]. Sterilization can also remove or strongly reduce reproduction-related behaviors, which can sometimes turn out to be quite problematic for guardians and their families. For instance, boarding a dog in heat is much more troublesome than boarding a spayed one. For the bitch, the removal of ovaries can help with the heats, which are often associated with the bitch wanting to run away, or with vulval bleeding. For the dog, castration can help with unwanted behaviors like dominance, aggression, urine marking, or roaming (to look for bitches in heat) [Hill et al., 2011]. It is also worth mentioning that castration on dogs who have aggression problems can be useful, but that it is not enough: a behavioral approach is necessary to help modify the dog's behavior [Hillet al., 2011].
- Medical advantages for females - The main medical advantage of surgical sterilization for females is that it is less likely for the sterilized bitch to develop some tumors. This way, the ovariectomy eliminates the possibility for bitches to have ovary tumors and strongly reduces the appearance of uterine and vaginal tumors. Moreover, it is less likely for a bitch to suffer from a mammary tumor if an ovariectomy or an ovariohysterectomy is made prematurely. If the surgery is performed before her first heats, it reduces the risk of having this tumor by more than 95%, if it is done before her second heats, the risk is reduced by more than 90%, and, if it is done before her third heats, it reduces the risk by about 75% [England et al. 2010]. This is probably the main medical argument in favor of the premature surgical sterilization of the bitch. Indeed, mammary tumors often occur among bitches (it represents around 50% of all tumors) and are usually malignant (around 50% of the mammary tumors are malignant) [England et al., 2010].The surgical sterilization for bitches also allows preventing the development of other pathologies linked with the uterus and the mammary glands, like pyometra (accumulation of pus in the uterus), mastitis (udder infection), and pseudopregnancy lactations (lactations without gestation) [England et al. 2010; Hill et al., 2011 ].
- Medical advantages for males - The main medical advantage of castration for males is that it avoids testicular diseases and decreasing the risks of the appearance of some prostatic diseases (except for most tumors). This way, castration eliminates the possibility for dogs to have testicular tumors and strongly reduces the appearance of some prostatic diseases (benign prostate gland hyperplasia, prostatitis). It is important to note that it is highly recommended to castrate cryptorchids male (when one testicle is not descended) because the risk of testicular tumors appearing for these animals is much higher [England et al. 2010;Hill et al., 2011; Root-Kustritz, 2007].
The disadvantages of the surgical sterilization.
- Disadvantages for both sexes - The most obvious disadvantage is that surgical sterilization is irreversible: the animal will not be able to reproduce. This can be a problem for the guardians who later wish to have descendants for their pets. In this case, chemical sterilization can be worth considering (see below).For animals who had a gonadectomy, the risk of gaining weight, sometimes to the point of obesity, is to be considered [England et al., 2010]. This is due to the fact that the appetite grows and, therefore, to the reduction of the metabolism. The fact that the animal is over-weighted can make other diseases appear, like diabetes [Walter, 2016]. This is why the food of the animal has to be adapted to reduce the energy intake. Some breeds are more likely to suffer from obesity after surgical sterilization, like Labrador Retrievers, Golden Retrievers, and Collies [Hill et al., 2011].Sterilization can also have abad impact on the quality of the dog's coat. We can sometimes notice on dogs with long and shiny hair (Cocker Spaniel and long-haired Dachshunds for example), an increase of outer coat, which negatively affects the quality of the coat. [Walter, 2016].Furthermore, some studies show that the removal of gonads increases the risk of having some cancers (hemangiosarcoma, transitional cell carcinoma, osteosarcoma, and some prostate tumors for the male) [Root-Kustritz, 2007]. However, we can note that an increase in the risk is low, and that the tumors are quite rare [England et al., 2010].And finally, what is noticeable is that there are some short-term complications risks because of the general anesthesia, and because of the surgery. The main complication thatwe can witness is intra-abdominal hemorrhage, which mainly affects big dogs [England et al., 2010]. The age and health of a dog have a direct impact on the risks related to the anesthesia and the surgery; this is why the veterinarian will, according to the dog, suggest further examinations prior to the surgery (blood tests, or even cardiac ultrasound).
- Medical disadvantages for females - For the sterilized female, the risk is to develop urinary incontinence. It can be eight times more likely for a sterilized bitch to suffer from this [Hill et al., 2011]. Urinary incontinence mostly appears several years after the surgery [England et al., 2010 Walter, 2016]. Urinary incontinence can often be cured with medicinal treatments, but, in some cases, surgery is necessary.And, less often, other complications can happen for sterilized females. Some bitches, especially big bitches sterilized before their first heats, can develop urinary excretion disorders associated with peri-vulva dermatitis [Walter, 2016]. Changesin the behavior, especially an exacerbation of the dominance behavior, have also been pointed out [Overall, 2007].
- Medical disadvantages for males - For males, the main disadvantage of medical castration is that it moderately increases the risks for the dog to have a prostate tumor in his lifetime [England et al., 2010 Walter, 2016].Furthermore, some dogs, especially those who have a placid behavior, can, in rare cases, become lethargic or disinterested in their surroundings after castration [Hill et al.,2011].
What is the best age to perform surgical sterilization?
For veterinarians, there is no consensus regarding the perfect age to do surgical sterilization on dogs and bitches [Hill et al., 2011; England et al., 2010 ]. Premature sterilization on a bitch is often recommended because it helps to prevent mammary tumors. However, some studies show that surgical sterilization performed before the bitch is 6 months, increases on some breeds the risk of hips and elbows dysplasia, and anterior cruciate ligament tear (especially Boxers, Goldens, and Labradors Retrievers) [Walter, 2016].In the end, each case is different, and the advantages and disadvantages of premature sterilization have to be discussed between the veterinarian and the guardians of the animal.
What are the alternatives to full surgical sterilization?
The first alternative to the full removal of the ovaries and testicles is the tubal ligation for the female, and the vasectomy for the male [Walter, 2016]. These options are rarely chosen in practice, probably because they do not enable the advantages regarding behaviors and health mentioned above (except, of course, for the fact that it avoids unwanted births).
There are also chemical alternatives to surgical castration.
- Chemical sterilization for the bitch - For the bitch, administrating some molecules (often progestagens) permits to inhibit the estrus (the heats) and so, to prevent ovulation and gestation. The use of these molecules have several disadvantages [Hill et al., 2011; England et al., 2010 ]:–the protocol can sometimes be quite complicated and, if it is not done properly, can lead to the failure of the chemical sterilization,–the long term cost is significant,–and, most importantly, the repeated use of these molecules can have harmful consequences on the bitch's health: there are high risks that the animal develops pyometra, diabetes, or mammary tumors.This is why chemical sterilization for the bitch should only be for short-term uses.
- Chemical sterilization for the dog - For the dog, chemical sterilization can be performed thanks to a molecule called deslorelin. The deslorelin can reduce the libido, the testosterone level, and the spermatogenesis for the adult dog, thus allowing efficient chemical sterilization. The deslorelin is implanted subcutaneously. Its effects usually last for 6 months and then fade away. This is why the maintenance of chemical sterilization includes the renewal of implants [Hill et al., 2011]. Unlike the chemical sterilization of the bitch, the use of deslorelin does not seem to be associated with the increase of risks of developing some diseases (but there are not a lot of studies about this). The main disadvantage of this option is the high price. However, it can be a good alternative for guardians who do not wish to have their dog surgically castrated.
The surgical sterilization of dogs is a routine intervention in veterinary medicine, but it is not a neutral act: it presents advantages and disadvantages. The choice to go through this procedure or not should be the result of a shared pondering between the veterinarian and the guardians of the animal; the reflection should take into account the age, sex, health, and way of life of the animal and the guardians.
Resources : BibliographyEngland, G.C.W., et al., 2010. BSAVA manual of canine and feline reproduction and neonatology, second edition. BSAVA publications.Hill, P et al. (eds), 2011. 100 top consultations in small animal general practice. Wiley-Blackwell.Overall, K.L., 2007. Working bitches and the neutering myth: sticking to science. The Veterinary Journal 173, 9–11.Root-Kustritz, M.V., 2007. Determining the optimal age for gonadectomy of dogs and cats. Journal of the American Veterinary Medical Association 231, 1665–1675.Walter, B., 2016. A quoi faut-il être attentif lors de castration chez le chien et la chienne? in Les 100 questions les plus fréquentes en clientèle canine. Point vétérinaire's edition, 148-150