By Dr. Shannon Leggieri, DVM, MS of Claremont Veterinary Hospital, Oakland.
Pyometra refers to an infection of the uterus. It is a very serious and life threatening condition requiring immediate medical intervention. Pyometra is preventable. Female dogs who have had their uterus removed are no longer at risk for this complication. Prevention of pyometra and decreased incidence of breast cancer are two important reasons to spay your dog early in life. If your dog is not already spayed it is important to discuss the benefits and risks of the procedure with your veterinarian.
If your female dog is intact it is important to recognize the clinical signs of pyometra early. Pyometra is the result of hormonal changes during heat and how those changes leave the uterus vulnerable to infection. There are certain “defenses” within the uterus which are essential for prevention of infection on a day to day basis. During heat these defenses are absent to allow sperm to enter the uterus without being damaged. At the same time an important hormone called progesterone rises and is responsible for thickening of the uterine lining in anticipation of pregnancy. This thickened uterus without the presence of immune defenses creates an ideal environment for bacteria to overgrow. This can lead to an infected uterus or pyometra. The more heat cycles a dog has gone through the more vulnerable they are to pyometra. Hence older dogs are more affected by this condition. Pyometra is most common two to eight weeks after heat has ended. It is important to track your dog's heat cycle to understand when they are most vulnerable to this infection.
Clinical signs of pyometra vary depending whether the cervix is “open” or “closed” during the infection. If the cervix is open you may see pus or discharge draining from the vagina. Sometimes you will see abnormal material adhered to the skin around the vulva or inside the inner thighs. These dogs will sometimes be lethargic, anorexic, and may or may not have a fever. Infections where the cervix is closed are more life threatening. These dogs can become severely ill quickly as bacteria is not able to drain out of the cervix and accumulates inside the abdominal cavity. These dogs are often vomiting, anorexic, feverish, and obtunded.
Pyometra is a surgical condition. If your dog is intact and has any of the above clinical signs, she should be checked by a veterinarian immediately. The most important diagnostic tool in these situations is clinical signs and timing of presentation. However your veterinarian may consider additional diagnostics such as x-ray, ultrasound and/or bloodwork. If pyometra is confirmed, immediate surgical intervention will be necessary. To remove the infection your veterinarian will be removing the uterus and spaying your dog at the same time. Following the surgery your dog will be on antibiotics and rest for a period. Follow up with your veterinarian during the postoperative period will be important.
