The proper terminology for an infection of the uterus with the presence of pus is pyometra.

There are other less severe conditions of the uterus common to female dogs and cats as well as people.

Metritis and endometritis are problems associated with the uterus but generally cause more chronic problems.

The uterus is truly an amazing organ where the developing fetus is.

Usually, a large, nonpregnant female dog will have a uterus about as big around as a pencil.

Then it will stretch to a phenomenal size when carrying six to 10 puppies to about as big around as a two-liter bottle of soda.

It has always amazed me how much the uterus can change and function as such a complicated organ responsible for the birth process.

If a dog or cat develops a pyometra, it is an emergency because they become sick, septic or toxic.

The infection causes many other organs to be affected and can cause organ failure.

Hormone changes that commonly occur when a female dog is in estrus or “in heat” are also part of the reason they may develop pyometra.

The hormones cause regular changes in the uterus, especially the inner lining that prepares it for the possibility of pregnancy.

Those changes also predispose the lining of the uterus to infection.

The most common time for a dog to develop a pyometra is approximately two to six weeks after their heat cycle.

Their cervix is open during estrus which gives bacteria access to enter the uterus.

Bleeding during their estrus cycle also allows for infection since blood is a perfect medium for bacteria growth.

Pyometra can occur in any age pet, but most commonly affects older pets. After many years of coming into heat, their uterine wall undergoes the changes that promote this disease.

The clinical signs of pyometra depend on whether or not the cervix is open or closed.

In a case of open pyometra, the cervix is open and there is a clear discharge of pus from the vagina.

If the infection is draining, the dog is not as sick clinically.

In a case of closed pyometra, the cervix is closed. It is more difficult to diagnose since there is no visible discharge.

A closed pyometra causes severe illness with symptoms of anorexia, listlessness, vomiting, and distended abdomen.

The toxins from the bacteria build up in the bloodstream affecting other organs.

The toxins will cause the kidneys to be unable to retain fluids and subsequently cause the dog to drink excessively, which usually occurs in both open and closed cervix pyometra.

Diagnostic tests may be necessary to diagnose pyometra, especially a closed cervix pyometra.

Blood tests are usually beneficial since dogs with pyometra have a severe elevation in white blood cells.

X-rays are incredibly helpful in the case of closed pyometra.

Typically, the enlarged uterus full of pus can be seen quite easily on the X-ray.

In more challenging situations, ultrasound can show the pus-filled uterus.

Treatment involves spaying the dog by surgically removing the ovaries and uterus, which is an emergency surgery to remove the infection inside the body as soon as possible.

Additional treatment such as intravenous fluids, antibiotics and pain medication are usually imperative for the dog to make a full recovery following surgery.

Another type of treatment to preserve the uterus and future breeding is available.

It is not always successful, and it can cause some severe side effects.

If a vet doesn’t perform the treatment quickly, the toxic effects from the bacteria may be fatal.

If the cervix is closed, it is also possible for the uterus to rupture.

A rupture will spill the infection into the abdominal cavity, which is just another reason to have your dog spayed as soon as she is old enough.

If your dog is not spayed and is showing symptoms of pyometra, see your veterinarian as quickly as possible.

Doing so will ensure your dog lives a long, healthy and happy life.

Dr. Jeff Castle is a veterinarian at Clark County Veterinary Clinic.