Pyometra (Canine)

Pyometra, or uterine infection, is common in unspayed female dogs. It is a serious condition that requires emergency surgery. Uncomplicated surgery often leads to full recovery.

Common name: Infected uterus
Scientific name: Pyometra

Diagnosis

Signalment
Pyometra is a disease that occurs in unspayed female dogs, most frequently over six years of age, with an average age of 7.8 years. It occurs commonly in all breeds, but is most prevalent in golden retrievers, rottweilers, collies and Cavalier King Charles spaniels. It is possible (though rare) for a spayed dog to get a stump pyometra in the uterine stump left after spaying.

Incidence/prevalence
Pyometra is believed to occur in approximately 22% of unspayed female dogs.

Geographic distribution
There is no known geographic predilection for this disease.

Clinical signs (primary, most to least frequent, scientific term, synonyms)
Vaginal discharge (not present in all animals with pyometra), Polyuria (increased urination), Polydipsia (increased drinking).

Clinical signs (secondary, most to least frequent, scientific term, synonyms)
Anorexia (not wanting to eat), lethargy, vomiting, distended abdomen (swollen belly), shock (decreased blood pressure and effective circulation).

Cause (scientific, common term)
Bacterial infection of the uterus.

Organ system affected (most to least affected)
Uterus, Kidneys, Sepsis (infection in the blood).

Diagnostic tests
Radiographs (X-rays), Ultrasound of uterus.

Differential Diagnosis
Pregnancy, Vaginitis (causing vaginal discharge), Mucometra or hydrometra (uterus filled with fluid other than pus), Postpartum metritis (inflamed uterus occurring after giving birth), Diabetes, Kidney disease, Cushing's disease, Any systemic disease, causing lethargy, poor appetite and vomiting.

Overview

Pyometra, or infection of the uterus, is very common, affecting approximately one quarter of unsprayed female dogs. It is a serious disease requiring emergency surgery to remove the infected uterus (while medical treatment is sometimes attempted for this disease, it is often ineffective, and can be dangerous). Pyometra occurs when the lining of the uterus gets overgrown under the influence of the hormones estrogen and progesterone, then becomes infected by bacteria moving up through the vagina into the uterus. If pyometra goes on long enough, it can affect the entire body, leading to critical disease, shock and death. A dog with pyometra will often have vaginal discharge, which can look like blood, pus or mucus. However, a dog with a closed pyometra (meaning that the uterus is sealed shut, not allowing any discharge out) will not have vaginal discharge. Furthermore, many dogs will clean themselves, removing any trace of vaginal discharge before it is visible to an owner. A dog with pyometra will usually seem very lethargic, and may drink and urinate more than usual. She may also vomit and not want to eat. If you have an unspayed female dog showing any of these signs, you must bring her to the vet immediately. You should never wait and see if you suspect that your dog has pyometra, since a dog with pyometra who is not treated (or who is treated too late) will usually die. The good news is that pyometra is extremely easy to prevent, simply by having your dog spayed.

Treatment

Home Care
There is no appropriate home care for pyometra. Physical examination by a veterinarian is required immediately.

Professional Care
The only dependable cure for pyometra is emergency surgery to remove the infected uterus (the ovaries are removed at the same time). Before performing surgery, the veterinarian will do a physical examination and x-rays or ultrasound to confirm an enlarged uterus, and blood tests. If the dog is not well enough to withstand anesthesia, IV fluids and medications will be administered until stable. After surgery, the dog will stay in the hospital on intravenous fluids, antibiotics, and pain medication, and will likely be discharged with antibiotics and pain medication for home administration.

Action
Pyometra requires immediate veterinary care.

Outcome
The majority of dogs with pyometra do well with prompt surgery. However, surgical delay can result in death from uterine rupture and systemic infection. Prevention of pyometra is easily achieved by early spay.

References/Additional Readings
Kustritz, MVR. Pyometra and Cystic Endometrial Hyperplasia. In: Tilly, LP and Smith, FWK, ed .The 5-Minute Veterinary Consult. Philadelphia: Lippincott Williams & Wilkins, 2004; 1100-1101.

Kustritz, MVR. Cystic Endometrial Hyperplasia and Pyometra. In: Ettinger SJ and Feldman EC ed. Textbook of Internal Medicine. St. Louis, Elsevier Saunders, 2005; 1676-1680.

Onclin, KM and Verstegen, J. Pyometra. In: Cote E, ed. Clinical Veterinary Advisor: Dogs and Cats. St. Louis, Mosby, 2007; 933-934.

Author
Andra Gordon-Gatica, DVM

Editor
Steven Hansen, DVM, MS, MBA, DABVT, DABT