Pros and Cons of Neutering or Spaying Your Dog
Photo: rmcnicholas

At this point, you're probably thinking about neutering or spaying your dog, but you're not so sure if this is a good idea. Not to worry, you're not alone in this. Many dog owners find themselves contemplating on this decision for a while, and rightfully researching the Internet for all kinds of answers to common sense questions:

  • What are the pros and cons of neutering or spaying a dog? 
  • Maybe I should leave my dog as nature has intended him/her to be?
  • What do dog experts and veterinarians think about this process?
  • Do all other dog owners spay or neuter their dogs?
  • What does science have to say about neutering or spaying your dog?

Rest assured, these are all valid concerns of a responsible pet owner, and we will address them as we go through this concise guide to neutering or spaying your dog.

For more details on this subject, I also recommend you listen Samatha's Theory of Pets podcast episode on the pros and cons of neutering/spaying dogs (link below).

LISTEN: Podcast on Pros & Cons of Neutering/Spaying Dogs

What is spaying and neutering of dogs?

Neutering is the de-sex procedure of male dogs where their testicles (or gonads) are removed. The actual removal of male dog's testicles is called Castration. Spaying is a similar procedure of sterilization for female dogs. In this case, females' ovaries and uterus will be removed, and this is called Ovariohysterectomy.

The main two purposes of this is to eliminate or at least decrease the chance of your dog developing certain types of diseases, and to control population growth of dogs. Neutering and spaying are also performed for many other animals, but dogs are the most common recipients of this unpleasantly sounding procedure.

But not to worry: neutering and spaying of dogs are done under general anesthesia, so your pooch won't feel a thing when a surgical incision is performed.

Dog owners will usually have their puppies spayed or neutered around the age of 6 months or earlier.

Spaying your dog: Pros and cons

Statistically, there are more pros than cons to making the decision of neutering or spaying your dog. It is highly recommended by vets to spay/neuter your dog for a variety of different reasons, some of which are listed below.

#1 Pro of spaying your dog: Heat period reduction

Pros and Cons of Neutering or Spaying Your Dog
Pro: Major health benefits. / Photo: Brett Davies

Spaying your female pet will prevent periods of her being in heat. When a female dog is in heat, her genitals swell and she lets out a scent that can be traced for up to a mile and attract unwanted attention from male canines.

Your female will also have less of a desire to wander and look for a mate, which would often result in additional dog behavior problems like escaping from home.

When in heat, she can have bloody discharge that will stain her coats and your furniture, her own dog bed or dog crate. By spaying your female pooch you don’t have to worry when leaving her alone in the yard or when taking her for walks. She will also be a much cleaner, calmer and more affectionate dog. 

#2 Pro of spaying your dog: No pregnancy

Spaying prevents your female from getting pregnant. Breeding, whether intentionally or accidentally, can become a large financial and time-consuming burden that also presents some health risks and responsibilities. There will be an increase in your vet bills and food bills. There is also a risk of death during birth or right after. Any complications during the pregnancy period of your dog will result in more vet bills and a health risk for the puppies as well.

If you decide to find homes for the puppies, that may prove to be much harder than you think. Normally, owners must keep the puppies with their mother until they are about 6 weeks old, and then try to find a home for them. Basically, it is far less expensive to have your dog spayed than it would be to have her get pregnant.

#3 Pro of spaying your dog: No risk of uterus and ovaries cancer

Spaying your dog will eliminate the risk of your pooch developing cancer of her uterus, ovaries and reproductive tract. When these organs are removed, you will have nothing to worry about (or rather, less things to worry about).

Even though these types of cancers are already very uncommon for female dogs to develop throughout their lives, many veterinarians advise that it's still a very valid reason to proceed with spaying your dog, and it doesn't hurt to be safe.

Aside from the above mentioned cancers, spaying reduces the risk of your female dog getting breast cancer if she is spayed before she reaches 2.5 years old. The more heat periods she has, the greater will be the risk that of her developing breast cancer.

Finally, spaying your female dog protects her from getting uterine infections. It's been observed that one in four unspayed female canines will contract a uterine infection. If left untreated, this disease can kill your pet.

#1 Con of spaying your dog: Hypothyroidism and weight gain

Pros and Cons of Neutering or Spaying Your Dog
Con: Potential weight gain. / Photo: Dale

Because your dog's endocrine system is affected, one of the more known side effects of spaying your dog is the risk of hypothyroidism. Low thyroid levels in a female canine will result in weight gain which is very difficult to fight even with adequate diet.

Your dog may also become lethargic, tired and start losing hair. Veterinarians recommend special medication to deal with hypothyroidism in dogs.

This problem can also be one of the reasons for your dog becoming overweight, and eventually you might need to start dealing with dog obesity. Very often, spayed female dogs start gaining weight at an increased rate after the procedure most likely due to changes in metabolism and hormonal structure.

Weight gain and dog obesity issue, however, can be avoided by when using an adequate amount of regular exercise, appropriate dog nutrition and otherwise providing your pet with a healthy and happy lifestyle.

#2 Con of spaying your dog: Cancers and other complications

It has been observed that spaying your dog increases the risk of deadly canine cancer called hemangiosarcoma. This disease affects dog's spleen and heart, which normally would've been protected by your pooch's reproductive organs.

Additionally, if done wrong or at the wrong age, even more complications can come through. For example, after spaying your dog, you might have her run the risk of uneven bone growth, bone cancer, urinary incontinence, and this procedure can also affect the appearance of their private parts.

Finally, abnormal vulvas can trap bacteria and cause dermatitis, vaginal infections, urinary tract infections, all of which should be considered.

#3 Con of spaying your dog: Sterilization and anesthesia

Spaying is a surgery of sterilization. That means your dog will never be able to become pregnant and there's no going back with this. However, given the overpopulation of dogs today with an incredible amounts of them being stray, homeless, living in shelters and euthanized, majority of pet advocates see this as a pro rather than a con.

Because the procedure itself has to be done using general anesthesia, there's a possibility that your pet will react poorly to this medication. Some research has show that about 1 in 5 dogs will have some complications after surgery under general anesthesia. However, most of these complications are not serious issues with a very low death rate.


Neutering your dog: Pros and cons

#1 Pro of neutering your dog: Reduction of male-type behavior

Pros and Cons of Neutering or Spaying Your Dog
Pro: Less aggressive dog. / Photo: Steve Baker

Neutering your male helps in reducing his desire to “mark” his territory. You may have noticed your dog’s need to lift his leg and spray, often times they will even mark inside the home. Neutering your male will help to greatly reduce his obsession with this type of behavior.

Also, a neutered dog will have a reduced level of aggression and dominate behavior. Since neutering involves removing the main source of testosterone, it can help mellow out your male dog.

Because of the lower level of testosterone and less aggression, neutered canines tend to be more affectionate and gentle than those that are not neutered. It also helps in protecting your male from non-neutered male dogs seeing him as a rival. Your dog will be less likely to get into fights with other packs or strays in the neighborhood, which saves you the cost of either going to the vet or the pain of finding your pet injured.

After neutering your dog, you'll reduce his sexual desires. He is less likely to hump other pets or objects. It will also help in keeping him from chasing down a female in heat. If he is not neutered, he will be able to sense a female in heat from up to a mile away and can get agitated. If he gets loose, he will try to track down the scent.

Neutered dogs are less likely to have the desire to roam. Since they are more mellow and not seeking a female in heat, they are more calm and stay closer to home.

#2 Pro of neutering your dog: Less health problems

Not only does neutering help in reducing unwanted behaviors, it also helps in reducing prostate problems. Prostate problems can occur in 80% of non-neutered males. Issues can include an enlarged prostate in dogs, prostate cysts and prostate infections.

Male dogs can sometimes experience the case of skin disease known as perianal fistula. This nasty condition develops carbuncles around your pet's anus and is often very complicated to treat. If neutered, the risk is highly reduced.

Testicular cancer can also be eliminated by neutering. Even though only 7% of non-neutered males get testicular cancer, having your male pooch neutered removes the risk entirely.

#3 Pro of neutering your dog: Control of breeding

Finally, neutering keeps your dog from breeding. Many pet advocates agree that it is irresponsible to allow your male dog to breed with strange female dog mostly because of the current overpopulation of canines.

Also, as a responsible dog owner, you would have no idea how the new puppies are being treated or if they are safe. While you may not have to shoulder any of the responsibility of the new litter, if you choose to help, there is the cost of food and vet bills.


#1 Con of neutering your dog: Hypothyroidism and obesity

Pros and Cons of Neutering or Spaying Your Dog
Con: Risk of dementia. / Photo: Ben Nguyen

Similarly to spaying your dog, male canines can experience the case of hypothyroidism, and studies have shown that neutering will almost triple the risk of obesity.

Once castrated, their endocrine system starts to function in a different way and hormonal levels are affected, which results in lower levels of thyroid, which then results is very rapid weight gain and eventually, dog obesity.

While hypothyroidism can be treated with medication after you consult with a veterinarian and confirm that it's definitely the case, your dog's weight gain must be addressed separately. Most dog owners will need to start feeding their dogs substantially less often and with less calorie dense foods. Regular exercise will also be needed as well as constant monitoring to see how this all is affected your pet.

#2 Con of neutering your dog: Dog dementia and bone problems

Neutered canines run the risk of developing dog version of dementia, which is actually called geriatric cognitive impairment. If this happens, your dog will start becoming disoriented wherever he is, even if it's the house where he has lived previously. Dogs with dementia will usually start interract different with humans and completely forget all the obedience training they've gone through.

For canines who were neutered at the wrong age in their life, or if the process was done poorly, there's a high risk of hip dysplasia, problems with ligaments and even potential to develop bone cancer known as osteosarcoma. The reason for all these bone and join related diseases is because male dog's reproductive organs are responsible for producing a sufficient amount of hormones and helping with the development of those body parts.

#3 Con of neutering your dog: Anesthesia risk

Again, same as with spaying your dog, neutering a male canine means that your pet will have to go through surgery which requires anesthesia. Therefore, there's a chance that your male canine will react poorly to anesthesia and as previously indicated, 1 in 5 dogs will have some complications after surgery under general anesthesia.

However, most of these complications will not be very serious with a very low death rate.

References and further reading:

  • Burrow R, Batchelor D, Cripps P. Complications observed during and after ovariohysterectomy of 142 bitches at a veterinary teaching hospital. Vet Rec. 2005 Dec 24-31;157(26):829-33. [study] 
  • Pollari FL, Bonnett BN, Bamsey, SC, Meek, AH, Allen, DG (1996) Postoperative complications of elective surgeries in dogs and cats determined by examining electronic and medical records. Journal of the American Veterinary Medical Association 208, 1882-1886. [study] 
  • Dorn AS, Swist RA. (1977) Complications of canine ovariohysterectomy. Journal of the American Animal Hospital Association 13, 720-724. [references] 
  • Pollari FL, Bonnett BN. Evaluation of postoperative complications following elective surgeries of dogs and cats at private practices using computer records, Can Vet J. 1996 November; 37(11): 672–678. [study]