Pyometra is an accumulation of uterine secretions under the influence of progesterone, possibly facilitated by oestrogens. It can be caused by the injudicious use of progestogens or progestogens and oestrogens (used to stop pregnancy after wrong mating). It does also occur naturally soon after oestrus (being in season/on heat). The fact that the womb is open to receive sperm also means it is open to infections creeping in, therefore whether or not a bitch is mated does not make a difference to the likelihood of a pyometra happening. It usually happens in the nine weeks after a season and is most common in the middle aged bitch. It may be wise to get bitches spayed when they have finished having pups as this is a life threatening condition if untreated.
The Signs are thirst, lack of interest in food, malaise, abdominal swelling and vomiting; (unfortunately most of these signs concur with that of the pregnant bitch) also puss like discharge from vulva in an open pyometra. If you have not mated your bitch the signs are more obvious, if you hope she is in whelp you think she is and do not treat her which can be fatal. A scan will show if she is in whelp, usually done at about 4 to 5 weeks into pregnancy and will also show if anything is amiss.
Diagnosis & Treatment is done using blood tests, radiotherapy and ultrasound. Ovariohysterectomy (spaying) is the treatment of choice, but anti-biotic drug therapy can be also successful. It is important to be vigilant for future signs of infection where there has been a previous case not treated by spaying. If you ever have any concerns about the reproductive health of your bitch, please consult your veterinarian.