The Patrician opened his eyes. ‘You are a doctor, aren’t you?’ he said.

Doughnut Jimmy gave him an uncertain look. He was not used to patients who could talk. 'Well, yeah… I have a lot of patients,’ he said.

'Indeed? I have very little,’ said the Patrician.

Terry Pratchett, Feet of Clay

‘What? You can’t mean… Doughnut Jimmy? He’s a horse doctor!’

'So I understand,’ said Vimes.

'But why?’

'Because many of his patients survive,’ said Vimes.

Terry Pratchett, Feet of Clay

When a human doctor, after much bleeding and cupping, finds that a patient has died out of sheer desperation, he can always say, ‘Dear me, will of the gods, that will be thirty dollars please,’ and walk away a free man. This is because human beings are not, technically, worth anything. A good racehorse, on the other hand, may be worth twenty thousand dollars. A doctor who lets on hurry off too soon to that great big paddock in the sky may well expect to hear, out of some dark alley, a voice saying something on the lines of 'Mr. Chrysoprase is very upset,’ and find the brief remainder of his life full of incident.

Terry Pratchett, Feet of Clay