I had been feeding a feral kitten for some time. A few days ago, I saw what looked like a gash next to its mouth, which darkened and didn't look like it was getting better a couple of days later. In addition, it had pink patches with no fur on it's right front leg, which was the leg it would use to rub the wounded area of its mouth. I also noticed it smells really bad, and there was what looked like dry mud or dirt on its legs.

I took it to a government vet who said it had Calicivirus, which needs treatment for a period of time. The kitten is not tame and was difficult to control at the clinic and was put in anesthesia.

The vet said it would be best to euthanize the kitten, as it would be difficult to control it to give it treatment and the illness would worsen and eat away much of the tissue on its face. They have no capability of holding cats there; they are either treated and released or put down.

I accepted his reasoning and expertise and thought it would be the most humane thing to do, especially since it was very difficult for me to trap the kitten the first time and I wouldn't want to watch it suffer and feel helpless if I couldn't trap it again.

Now I feel guilty and worried that the kitten might have gotten cured by itself upon reading about the disease.

Was the vet right/ethical about his decision?