Chloral hydrate is conditionally acceptable for euthanasia in large animals that are:

Chloral hydrate is recognized for its use in euthanasia protocols primarily when the animal is already sedated. This is because sedation helps to minimize distress and discomfort associated with the procedure. When an animal is sedated, it is in a calmer state, making the administration of euthanasia agents smoother and more humane. The use of chloral hydrate in a sedated animal enhances the chances of a peaceful and painless transition, aligning with ethical guidelines for animal welfare.

The option regarding animals that are easy to restrain may imply that physical restraint is necessary, which can cause additional stress and should generally be avoided in euthanasia scenarios. Euthanasia should be performed in a way that prioritizes the animal's well-being. The option about animals in pain brings into question the ethical implications of euthanasia and the potential role of pain management, rather than focusing solely on the method used for euthanasia. Lastly, while the condition of being free from infection could be a consideration for overall health, it does not necessarily relate to the immediate context of euthanasia practices with chloral hydrate. Therefore, the most appropriate and ethical scenario for the use of chloral hydrate in euthanasia is in animals that are already sedated.