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WHAT IS PYOMETRA?
HOW DOES BACTERIA GET INTO THE UTERUS?
Pyometra is a uterine infection caused by hormonal changes, usually following an estrus cycle (“heat” cycle). This occurs when progesterone (an important hormone for maintaining pregnancy) levels are persistent after estrus has ended. This causes the walls of the uterus to thicken and eventually cysts form within it. These cysts excrete fluids and the uterus essentially acts as an incubator, promoting the growth of bacteria. High progesterone levels will inhibit the ability for the uterus to contract.
Typically, the cervix remains tightly closed except during estrus. Bacteria is naturally found in the vagina and when the cervix is open, bacteria can easily find its way into the cervix. If the uterus is normal and healthy, the environment is not ideal for bacteria to survive and replicate, but when the walls of the uterus is thickened and cystic, the uterus cannot contract and expel the bacteria on its own.
Ovaries
WHAT ARE THE SYMPTOMS?
A pyometra can be open-cervix or closed-cervix. If the pyometra is open, this allows the pus to drain out of the uterus and vagina onto bedding, fur, or anywhere the pet is laying or sitting. If it is closed, the pus is not able to drain and can cause the abdomen to enlarge. Fever, lethargy, inappetence, depression, an increase in thirst and urination may also be present.
HOW IS IT TREATED?
The preferred treatment is ovariohysterectomy (OVH), also known as spaying – the removal of the uterus and ovaries. If the animal is used for breeding, owners may elect medical treatment such as prostaglandin F2α therapy which is more promising for pets with open-cervix pyometra. Prostaglandins are a group of lipids made at sites of tissue damage or infection that are involved in dealing with injury and illness. They control processes such as inflammation, blood flow, the formation of blood clots and the induction of labor.
MORE INFORMATION
Ovariohysterectomy (spaying) prevents this disease. If an animal develops pyometra, early and aggressive treatment presents the best results. Animals with pyometra have a 5%-8% mortality rate with ovariohysterectomy (spaying). If medical treatment is elected instead of spaying, 26%-40% have a recurrence within one year. Medical treatment is more successful when the cervix is open and draining.
A normal dog uterus after spay
This is an example of a normal dog uterus after a spay. Note the size of it compared to the next slide.
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