Why You Shouldn't Spay Your Pet in Heat

puppy at vet office

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You meant to have your dog or cat spayed before she came into heat, but you didn't expect it to come so soon! Dogs and cats usually have their first heat cycle between six months and a year of age, but it can happen as early as four months old. Although you can ask your vet to spay a dog or cat in heat (also known as estrus), many vets prefer to wait until the heat cycle is over to be safe; if the spay is done while the animal is in heat, the costs are usually a little higher as well. The size, age, and overall health of the pet are factored into the decision, but it's always better to err on the side of safety in matters concerning your best furry friends.

Planning Ahead

It is generally recommended to spay your pet by six months of age if you want to avoid having her go into heat. If the animal is spayed before the first estrus cycle, the chances of mammary cancer are greatly reduced. Spaying at any age eliminates the chance of ovarian and uterine cancers, as these organs are removed during a typical spay.

The ideal age to spay and neuter is a topic of much debate. Speak to your veterinarian about your specific pet for advice on the best age to spay. Many experts feel that spaying before the first heat cycle is best for the pet and most agree that it is best to avoid spaying when in heat if possible. However, recommendations may vary based on the breed and size of your pet as well as current research.

Sometimes an appointment is made far in advance or an animal is found or rescued and the estrus status is not known when the surgery is scheduled. This may result in your pet being brought in for her spay while she is in heat. If this is the case, speak to your veterinarian about possible risks and added costs of spaying the animal while she may be in heat.

Spaying While in Heat

During a heat cycle, the blood vessels that supply the ovaries and uterus are engorged. Additionally, these tissues are more "friable," meaning they may tear more easily than normal and then bleed more. Even tissue not associated with the reproductive organs such as skin, fat, and muscle will often bleed more than normal during surgery. This makes a typically elective surgery more stressful than it needs to be and carries the additional risk of bleeding problems during the surgery or post-operatively. Because of this, some veterinarians will not spay a pet in heat and recommend instead that surgery be scheduled for a week or two after the cycle ends.

Some veterinarians are selective about the type of pet they will spay while it is in heat. In general, cats that are in heat are easier to spay than dogs that are in heat. Small dogs are easier than large dogs. Overweight pets are difficult to spay both in heat and not in heat. Anesthesia is riskier for overweight animals too—just one more reason to make sure your pet is a healthy weight.

Additional Costs

If a pet is spayed while in heat, the surgery takes longer and additional surgical supplies such as gauze sponges and sutures may be needed. The medications used before, during, and after the procedure may be different from those used on a routine spay. Therefore, the cost of the procedure will be higher to cover the extra time and supplies needed.

Waiting to Spay

If your dog or cat is in heat, you may have decided to wait until she is out of heat for surgery. This reduces the risk of surgery and lowers the cost of the procedure. However, it is important to watch your dog or cat very carefully until she is out of heat. During this time, she may try to sneak out of the house or yard, especially if there are males nearby. 

Remember that your dog or cat is very receptive to males at this time as she is hormonally inclined to mate. If she does manage to mate with a still-fertile male, you may end up dealing with a pregnant dog or a pregnant cat. Then it becomes a question of whether to spay her and terminate the pregnancy or wait for a litter of puppies or kittens. Avoid adding to the pet overpopulation problem and do everything possible to avoid accidental mating; dogs and cats should not be bred unless they are excellent quality purebred animals and you are an experienced, responsible breeder.

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.