Yees, I had an elderly Clydesdale mare who had a swollen knee. Vet decided that it was caused by heart failure and we had her pts shortly aftrwards. She owed us nothing and we owed her a dignified end.
In a donkey yes. She was very elderly and began to show swollen legs and fluid under her belly. Vet believed she was heading into heart failure and she was put down approx 36 hours after the first swellings came up.