Horner's syndrome and ipsilateral laryngeal hemiplegia in three cats.

Horner's syndrome is described in three cats associated with wounds to the ventrolateral neck. In each case, ipsilateral laryngeal hemiplegia was observed on laryngoscopy. This finding provided strong evidence to support a diagnosis of second order Horner's syndrome due to disruption of the cervical sympathetic trunk, as motor fibres innervating laryngeal abductors also traverse the neck; both as descending fibres within the contiguous cervical vagus and as ascending fibres within the recurrent laryngeal nerve. Notably, the ability to vocalise was unimpaired in all cases and, in two cats, neck wounds were not apparent until the neck had been clipped and closely examined. These findings indicate that assessment of laryngeal function is of value when localising the site of the neural defect responsible for selected cases of second order Horner's syndrome.