what is pyometra in dogs?
A pyometra is a serious bacterial infection in the reproductive tract that causes purulent (pus or pus-containing) material to develop in the uterus. this occurs as a consequence of hormonal changes in female dogs.
Cystic endometrial hyperplasia is often used synonymously with the term pyometra, and although these terms are often associated with each other, they are not the same. Cystic endometrial hyperplasia is a thickening of the uterine tissue that creates an ideal environment for a pyometra to occur.
Reading: Endometriosis in dogs
Bacteria and toxins from the infection can seep through the wall of the uterus and into the dog’s bloodstream, causing a body-wide infection (sepsis). the uterus becomes very fragile and pus may begin to leak into the abdomen.
Without treatment, this can be a life-threatening condition.
pyometra symptoms in dogs
The symptoms of a pyometra can be vague and can resemble other types of infectious diseases. Typically, a veterinarian would suspect pyometra in a bitch who ended her heat cycle approximately 1 to 2 months early and has one or more of the following symptoms:
pustular to bloody vaginal discharge
lack of appetite
drink a lot of water
With an “open” pyometra, the cervix is open and infectious material inside the uterus leaks through the vagina/vulva. You may see a small to moderate amount of this pustular material on your pet’s vulva or tail, but you may also notice it on your pet’s bed or where it has been sleeping.
However, a pyometra can also occur with a closed cervix. in this case, no discharge will be able to escape from the uterus, making diagnosis difficult. Since the infection is trapped inside the body, these dogs have more severe symptoms.
While this is a disease of unspayed females, there can be a very rare infection of the uterine tissue that remains after a pet is spayed. We call this “stump” pyometra. the symptoms will be very similar to a standard pyometra, but the pet may have been spayed many weeks or years earlier.
causes of pyometra in dogs
Starting at about 6 months of age, once the pet reaches hormonal maturity, the bitch will go through a heat cycle every 6 months or so. each cycle brings the possibility of pregnancy. the uterine lining will thicken in preparation for potentially being home to a growing embryo.
Rarely, the lining continues to thicken abnormally and cysts form from glands within the wall of the uterus. this abnormal tissue becomes excessive and persistent. It is called cystic endometrial hyperplasia (CEH).
The exact cause of ceh is not known, but the hormones progesterone and estrogen during successive cycles are definitive factors. Successive cycles means that the likelihood of a bitch developing pyometra increases with each heat cycle she goes through, as the hormonal effects accumulate in utero.
However, pyometra can occur in any reproductively active pet, including dogs that are only 4 to 6 months old. once ceh occurs, the swollen uterine tissue is a great breeding ground for infection. while the uterus is a sterile environment, the vagina is not. bacteria from the vagina travel to the uterus and become the source of infection for pyometra.
The bacteria that most commonly cause pyometra are Escherichia coli (E. coli), Staphylococcus, Streptococcus, and Pseudomonas.
how veterinarians diagnose pyometra in dogs
When a pyometra is open, the purulent/pustular vaginal discharge makes the diagnosis of a pyometra much easier. when there is no discharge, diagnosis can be challenging. Your vet may do the following to confirm a diagnosis:
blood test: While there is no specific blood test to diagnose pyometra, the blood test tends to be consistent with a generalized infection or inflammation. Typically these puppies will have very high levels of white blood cells; however, with dogs that have severe infections, it is possible for white blood cell counts to be normal or even low as the white blood cells leave the blood system and make their way to the uterus to begin fighting on the front lines.
An increase in a particular group of blood proteins called globulins may also be seen, as these blood proteins are often increased when the immune system is active. liver and kidney damage can also be seen with severe infections.
X-rays or X-rays: X-rays tend to show an enlarged uterus. the uterus may be very swollen, making it easier to diagnose pyometra. other times, it is not so obvious and confirmation with ultrasound may be necessary.
ultrasound: an enlarged uterus does not always mean a pyometra; this could also be explained by pregnancy, hydrometra (distention of the fluid in the uterus), uterine torsion (twisting of the uterus), or cancer. An abdominal ultrasound can be very helpful in differentiating between a pyometra and other possible conditions.
physical exam: Your veterinarian will evaluate your dog with a physical exam and weigh the results of diagnostic tests to determine the best course of treatment.
treatment of pyometra in dogs
Surgical removal of the uterus and ovaries, the definitive treatment for a pyometra, removes the source of the hormones and the infected uterine tissue. if the ovaries are not removed, they will continue to produce hormones that can affect even the small stump of the uterus that remains.
This surgery is much more complex than a routine sterilization, although both surgeries remove the ovaries and uterus. once the uterus is infected, it can be quite difficult to remove it safely.
Many dogs will require intravenous (iv) fluid therapy to help with dehydration and electrolyte abnormalities before surgery can be performed. antibiotics are usually given during surgery and are continued for 7 to 14 days after surgery.
Pain relievers are needed after any major surgery, and pyometra surgery is no exception. most dogs will likely need to be hospitalized for 24 to 48 hours after surgery to receive ongoing care.
Treatment of stump pyometra involves removing the infected uterine stump and finding and removing the source of hormones that caused stump pyometra to form in the first place. this may be a small piece of ovary left behind after sterilization or, rarely, a piece of ectopic ovarian tissue, where the hormone-producing cells are outside the normal locations of the ovary.
For breeding animals, there is a medical approach to treating pyometra. however, it is often not recommended as the success rate is variable. there is considerable risk, and long-term reproductive complications often still occur. discuss this alternative thoroughly with your reproductive veterinarian.
recovery and prevention of pyometra in dogs
Prevention is the key to success, as a spay/neuter procedure usually prevents pyometra from becoming a problem. If your pet has pyometra surgery, home surgical recovery is similar to spaying:
Your puppy will need a quiet, safe space to stay during recovery. a large kennel or small room is preferred.
Limit activity to leashed walks for elimination purposes only, as any increase in activity may place additional stress on the incision site.
It is very important that your pet does not lick the incision. an electronic collar or surgical suit will help with these recovery efforts.
Check the incision daily for redness, swelling, or drainage.
Medications such as anti-inflammatories, pain relievers and antibiotics should be administered as directed by your veterinarian.
If your dog is not eating or is experiencing lethargy, pain, vomiting, or diarrhea, contact your veterinarian immediately.
pyometra in dogs frequently asked questions
veiga, gisele almeida lima, et al. “Cystic endometrial hyperplasia-pyometra syndrome in bitches: identification of hemodynamic, inflammatory, and cell proliferation changes”. reproductive biology, vol. 96, no. 1, 1 jan 2017, pp. 58-69.
merck veterinary manual. pyometra in small animals—reproductive system.See also:
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