Pyometra is a life-threatening uterine infection that affects unspayed female dogs, causing acute suffering, systemic sepsis, and death without emergency surgical intervention.
Pyometra causes acute, rapidly progressing suffering. Toxemia from bacterial infection causes systemic illness within days of onset in closed forms. Rupture with peritonitis is agonizing and rapidly fatal. The condition is almost entirely preventable through routine spaying. The welfare calculus is clear: the acute suffering of pyometra, the stress and cost of emergency surgery, and the mortality risk in untreated cases all argue strongly for proactive spaying as a welfare-positive intervention for dogs not intended for breeding.