Page 515 - The Veterinary Care of the Horse

Headshaking is a term used to describe a horse’s behaviour when it repeatedly tosses its head

in response to nasal or facial irritation or pain. In many cases it occurs in response to
VetBooks.ir hypersensitivity of a branch of the trigeminal nerve (fifth cranial nerve), which provides
sensation to the face, nose and muzzle, causing the horse to experience sudden severe facial

pain. This is a serious and distressing neurological condition.

Anatomy

The trigeminal nerve divides into three branches – the ophthalmic, maxillary and mandibular
(Figure 11.12). The infraorbital nerve is a branch of the maxillary nerve that runs through the
infraorbital canal and emerges through the infraorbital foramen halfway down the horse’s

face and runs superficially under the skin towards the muzzle. It supplies sensation to the
upper lip, nostril, gums and teeth.