My dog had pyometra back in 2004 and had to undergo an emergency hysterectomy.

Recently, after breaking her leg, she got stump pyometra. This was caused (according to my vet) from an infection on a remaining piece of uterus left behind after the hysterectomy. Hopefully this has cleared up after a strong course of antibiotics.

It is very strange that both times she got pyometra, she had damaged a leg. The first time she ripped a tendon in her back leg and the operation to fix this had to be put on hold until she had fully recovered from the hysterectomy. This time she has broken her front leg.