All About Spaying a Dog

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Spaying is a common surgical procedure in dogs. It can have health benefits for your dog, but not without risk. What can you expect when getting your dog spayed?

What Is a Spay?

A spay is the colloquial term for an ovariohysterectomy. Ovario meaning ovaries, hyster meaning uterus, and ectomy meaning removal. So an ovariohysterectomy is literally the surgical removal of the ovaries and uterus. It’s interesting to note that while removing both the ovaries and the uterus is commonplace in the US, simply removing the ovaries and leaving the uterus (an ovariectomy) is the procedure of choice in Europe.

Why Do Dogs Get Spayed?

There are a few reasons one may want to spay their dog. For dog owners, a common reason is to prevent heat cycles and unwanted/unexpected litters of puppies. Other common reasons include avoiding serious health risks, like pyometra (emergency infection of the uterus) or breast cancer.

Preventing Heat

Intact female dogs go into heat, on average, twice a year. This is when an intact female can become pregnant with puppies. An intact female dog’s estrus cycle, or the recurring cycle of physiological changes dictated by reproductive hormones, is broken down into four stages. The proestrus, estrus, diestrus, and anestrus stages with estrus being the period in which a dog is in heat. The ovaries are the organs that produce the estrogen that controls the estrus cycle. Once these are fully removed, there is no estrogen production. Without estrogen production, the estrus cycle ceases. Therefore, a spayed dog cannot get pregnant but she also can’t go into heat.

There are also medical reasons to spay your dog. Spaying a dog can prevent various disease processes, especially the extremely common and life-threatening conditions of pyometra and mammary cancer (breast cancer).


This serious and life-threatening condition, pyometra, is an infection of the uterus caused by uterine exposure to the hormone progesterone during diestrus. Pyometras often occur 2-3 months after a heat cycle. It’s reported that 1 in 4 intact female dogs will get a pyometra by the time they reach the age of 10.

Pyometra can be classified as either open or closed. An open pyometra is characterized by discharge that can be bloody and purulent coming from the vulva. A closed pyometra means that the infection and discharge is trapped within the uterus. While both are urgent concerns, closed pyometras are much more concerning. This is because a closed pyometra means the uterus will fill up with pus and blood quicker and may rupture sooner or more easily.

Pyometra can lead to sepsis, where the infection may enter the bloodstream, or the uterus may rupture, leading to a septic abdomen, septic shock, and death. Treatment for pyometra is emergency spaying. This is much more difficult than a typical spay, and often requires additional treatment, medications, and supportive care. Patients with a pyometra are often much sicker and medically fragile, so spaying before a pyometra occurs is important to reduce this risk in dogs. Spaying your dog prevents this common medical emergency.

Mammary cancer

Breast cancer, or mammary cancer, is a common health risk of intact female dogs, and occurs at an even higher rate than in humans. Mammary tumors occur in 23-34% (also 1 in 4) of intact female dogs, and make up close to 42% of all diagnosed tumors. Additionally, half of all mammary tumors are malignant, meaning that they may spread to other areas of the body and cause more problems body-wide.

Mammary tumors typically develop in mature mammary tissue due to the hormones, but spaying a dog before their first heat cycle often prevents the maturation of this tissue due to removal of ovaries and hormones. Dogs who are spayed before the heat cycle have a significantly decreased risk of developing mammary tumors, down to 0.5 %. Dogs spayed after their first heat cycle also carry a lower risk of mammary tumors, 8%. However, waiting to spay your dog after multiple heat cycles reduces the benefit of spaying, and 25% of dogs are likely to develop mammary tumors.

Monitor your dog's belly for lumps and have them checked by a veterinarian as soon as they are noticed. Additional signs to watch for and call your vet include swollen glands, painful abdomen, discharge from glands, ulceration of skin, weight loss, and lethargy.

False Pregnancy

 False pregnancy is an unusual but non-life-threatening complication of the estrus cycle that’s not fully understood. Oftentimes, intact female dogs suffering from a false pregnancy will exhibit behavioral changes such as nesting behaviors or being more aggressive than their normal temperament. The most common clinical symptom of false pregnancy are enlarged mammary glands with or without the production of milk. Breeds of which a false pregnancy may be more common include Caucasian shepherds, German shepherds, mastiffs, and Rottweilers

What Are The Risks of Spaying?

Spaying, although a common procedure, is a major surgery. The uterus and ovaries are within the abdominal cavity, where other major organs like the spleen, liver, kidneys, and urinary bladder are. Aside from the risks that come with general anesthesia, there are risks associated with a spay surgery.


The ovaries and uterus of a dog can be quite vascular, especially when in heat. Although common surgical procedures involve ensuring vessels are more than adequately located or tied off, hemorrhage can be a risk with a spay, especially if dogs are not rested adequately after the procedure. This risk can go up if a dog is in heat, which is why your vet may want to postpone your dog’s spay surgery if she happens to be in heat the day the procedure is scheduled. Typically, dogs are given a 10-14 day period of exercise restriction following their spay to minimize the risk of them dislodging sutures used to tie off blood vessels.

Ovarian Remnant Syndrome 

Ovarian remnant syndrome occurs when there is still functional ovarian tissue after a dog is spayed. It is important that all ovarian tissue is removed during spay surgery, but in rare cases, a small piece of ovarian tissue may be left behind. Ovarian remnant syndrome may also be caused by ectopic ovarian tissue (tissue growing outside of the normal position) or even adrenal tumors, which continue to production estrogen. Dogs suffering from ovarian remnant syndrome will exhibit classic signs of being in heat. Treatment typically involves surgically removing the remaining ovarian tissue.


Dehiscence is when the incision fails to heal properly and opens back up. It’s most often caused when a dog licks at her surgery site and opens up her incision. It may require a second surgery and second time under anesthesia for veterinary attention to clean out the open incision and re-close the surgery site. Additionally, depending on the level of dehiscence, this may occur in deeper levels than the skin, potentially damaging internal tissue and organs. This is one of the main reasons dogs should be kept in an Elizabethan collar 24/7 until sutures are removed or spay site is checked by your veterinarian after healing.


This is a build up of clear, serous bodily fluid where tissue has been removed. It can manifest as a bump on or near the surgical incision but it won’t be red, warm, or have any associated discharge. Seromas are more common in dogs that are active immediately after surgery, and is another reason to follow exercise restrictions following surgery.

Urinary Incontinence

This is an involuntary loss of control of the lower urinary tract. There may be an increased incidence of urinary incontinence in some breeds when spaying before 1 year of age.

Joint Disorders

Joint disorders are being researched as another possible long term complication of early spaying. Bone growth varies in the dog, and if a spay is done before 6 months of age in large breed dogs, an increase in joint disorders have been observed in some studies. The studies done that demonstrate this have shown some correlation in Golden Retrievers, German Shepherd Dogs, and Labrador Retrievers. Many veterinarians recommend delaying spaying larger breeds until after 6 months. This risk has not been universally seen across all breeds and more research is being done to further understand this.

There are many additional factors involved in joint disorders, including a rise in pet obesity. Your veterinarian can help with the timing of the spay to minimize all risks, and these decisions should be tailored for the individual situation. Often the decision is made with a balance of minimizing the risk of mammary tumors, which occur more frequently and are more life-threatening. Additionally waiting until dogs are larger also means that the surgery is more involved and there is more risk of hemorrhage.

After the Spay

Most veterinary clinics will treat a spay surgery as an ‘outpatient’ type of procedure. That is, oftentimes your dog does not need to be hospitalized overnight. Your veterinarian will prescribe pain medication for your dog to take. Oftentimes the pain management protocol will include a non-steroidal anti-inflammatory drug, but this medication cannot be taken in combination with certain other medications, including steroids, so be sure to let your vet know all of the medications and supplements your dog is currently taking.

It is of the utmost importance that you prevent your dog from licking at their incision to prevent dehiscence and to keep them quiet and calm to prevent seromas. Some veterinarians may also prescribe an anti-anxiety medication called trazodone to help keep dogs quiet and calm during the recovery process. Elizabethan collars serve to prevent your dog from being able to lick the incision.

Seek veterinary attention if the incision ever becomes red, inflamed, or warm to the touch. Most dogs bounce back quickly from their spay surgery and are back to normal the following 1-2 days post-op. If your dog is acting lethargic, not eating or drinking well, or if they are having any diarrhea or vomiting let your vet know.

Spay surgeries are common surgeries performed in veterinary practices. If you have concerns, your veterinarian can give more insight about both the risks and benefits of spaying your dog. Your veterinarian's goal is to improve your pet's health and help to provide options to reduce health risks to your pet.

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