Most of us have our pets spayed and neutered during the first year of life to avoid pregnancy and contributing to the pet overpopulation.  However sometimes the surgery is delayed for various reasons whether financial, being told by a previous owner that the surgery was done, “silent” heat cycle, to have the option to breed in the future or assuming that the animal will go through menopause.   If the spay surgery is not eventually performed, several possibilities can occur including pyometra (an infection/inflammation of the uterus), unwanted pregnancy and tumors of breast.

Unwanted pregnancy is always concern since we have not planned for finding homes for the puppies/kittens which often are not purebred.  There is also the risk that the male that sired the puppies may be significantly larger than the female causing larger puppies that she can deliver, requiring a cesarean section adding to the costs.

The hormones that the ovaries produce can cause future development of breast tumors that can spread to the lymph nodes, lungs and other vital organs even if the animal was spayed before they appeared.  The risk is highest in animals that are not spayed by two years old.

The chances of pyometra occurring increases each time the animal goes through a heat cycle and is not bred.  Due to this, most affected animals are middle aged to senior in age and unlike humans, dogs and cats don’t have a menopause cycle and continue to go into heat their entire life.  But like in humans, endometritis is a common cause leading to the disease and can lead to either an open (active draining) or closed (trapped) infection.

If you don’t see drainage, other non-specific signs include loss of appetite, lethargy, increased drinking, vomiting, diarrhea and possible belly distension.  After examination and getting a history, bloodwork, x-rays and sometimes urine sample will be collected.  The bloodwork is looking at kidney function and increased white blood cells.  While x-rays can show an enlarged uterus, it is possible that an ultrasound maybe needed to diagnosis the disease.

The best treatment is surgery to carefully remove the enlarged infected uterus, intravenous fluids and antibiotics.  The earlier the surgery is performed and if there is active drainage the better the prognosis to avoid the uterus rupturing into the belly.   There are reports of using medicines to treat using a combination of prostaglandins, antibiotics and opening the cervix, but this delays improvement increasing damage to the body and the chance of relapses.

It is important to schedule a spay if you are not going to breed to prevent future complications that have been discussed.