Some animals who come into hospital require restraint for the procedure that they are undergoing. In cases where we require complete unconsciousness, such as dentistry or surgery, general anaesthesia is necessary.
In other situations, for example some wriggly animals for x-ray or for grooming, or some aggressive animals for any procedure, we do not need to give them a full general anaesthetic: instead we sedate them.
Sedation is a state where the animal is not entirely unconscious, but its awareness of its surroundings is severely altered and it does not have control of its muscles.
People who undergo the types of sedation we use do not remember having undergone the procedure afterwards, and this appears to be the same in animals.
It is important that the animal is fasted before undergoing sedation, just as it would be for a general anaesthetic. The reason is that it may lose control of the muscles controlling swallowing: if there is any regurgitation of food from the stomach it may be breathed into the lungs and the animal may develop a life-threatening pneumonia.