Hair loss (also called alopecia) in rabbits can be caused by several disorders - and a veterinary diagnosis is necessary to treat the underlying cause
Hair loss can occur as a normal part of moulting, after which the coat can look sparse but it will grow back again. Moulting usually occurs seasonally, after the winter has ended and the thicker coat that has grown is not needed for protection against the cold.
There are many diseases that can lead to excessive hair loss including the following :
Nest building - rabbits will pull out hair to add to other materials in the nest
Dominance behaviour by other rabbits
Excessive grooming by overzealous owners
Behavioural vices - boredom, stress
Ectoparasites - eg mites such as sarcoptes and demodex which cause itchiness and self-trauma - rubbing or biting
Infections (bacteria or fungi) - causes localised hair loss, and self-trauma - rubbing or biting
Nutritional deficiency - eg inadequate fibre intake has been reported to result in hair loss
Local reactions to injections such as vaccines can result in hair loss