(‘Pyo-‘ – accumulation of pus, ‘-metra’ – uterus)

This is the most dangerous and most common condition of the non-spayed female dog. It classically occurs in older bitches that have not had a litter, but can occur in parous dogs (those that have whelped) and in young dogs.

The condition starts when the bitch comes into season (oestrus). It is at this time that the cervix allows bacteria to ascend the reproductive tract. Over time these bacteria multiply and pus builds in the uterus causing the dog’s health to deteriorate.

Often the bitch will become inappetent, weak and may start vomiting. Quite frequently the sepsis that develops affects the kidneys which leads the development of an increased thirst. If the cervix is open at the time of diagnosis a putrid vulval discharge may be seen (the ‘open pyometra’) the absence of a discharge means it can be assumed that the cervix is closed (the ‘closed pyometra’). In both cases the enlarged uterus causes abdomen distension.

Toxins from the bacteria enter the bloodstream and can cause a number of further concerns including heart rhythm disturbances, liver enzyme changes, a high temperature due to the sepsis and dangerous imbalances in the body electrolyte and fluid levels.

Diagnosis depends on the owner describing any of the above signs to the the vet, who may then suggest a confirmatory ultrasound scan. Other tests, especially blood tests and heart checks may also be recommended before treatment starts.

Antibiotics will always be used to control the infection, quite frequently given by intravenous injection. The dog’s fluid and electrolyte imbalances will be corrected by using a drip and this may also need to be supplemented with glucose as hypoglycaemia is also a risk in these animals.

Ultimately treatment must ensure that the pus is eliminated from the uterus and this is usually managed by ovariohysterectomy (speying). The speying procedure is not, however, as straightforward as the elective procedure performed on a healthy pet. The uterus must be handled with great care as the distension with pus makes uterine rupture a very real risk. Once performed, however, the bitch should start to feel better very quickly.

An alternative way of eliminating the pus from the body is to use medication. Originally prostaglandins were used. These were never a licensed medication for dogs and they caused many side effects which made their use difficult to justify. More recently another medication called aglepristone has been licensed for use in dogs. This is only licensed for terminating pregnancy in dogs but it has been used off license as an alternative treatment for pyometra with antibiotic cover. The medication may be seen as a viable option if the bitch is being considered for breeding in the future.

Owners of all female dogs should be aware of this condition which poses a significant risk to their lives if left untreated.