PARTICULARITIES OF HORNER'S SYNDROME IN DOGS AND CATS: A LITERATURE REVIEW

Abstract

Horner's syndrome (HS) is a neurological alteration resulting from the interruption of the sympathetic innervation of the eyeball, characterizing the ophthalmic clinical signs; miosis, enophthalmos, eyelid ptosis, and prolapse of the third eyelid. The sympathetic nervous tract of the eye is extensive, dividing into central, pre- and post-ganglionic neurons, or first, second, and third-order neurons, as mentioned in older literature. From this, HS should be classified according to the neurolocation of the lesion, there are other possibilities that are not well elucidated, such as hypothyroidism and idiopathic presentation. The gold standard definitive diagnosis is made through the instillation of 5 to 10% cocaine-based eye drops, however, due to the difficult access, the 1 to 10% phenylephrine solution can be a substitute, in both cases the animals positive for HS continued with miosis and the other signs already presented. Because it is a disease secondary to an injury during the nervous tract, a systematic investigation using imaging tests is necessary, since treating the underlying cause is the beginning of treatment. This, as already mentioned, will depend on the location of the lesion, for symptomatic treatment phenylephrine 1 to 10% is used, which temporarily relieves parasympathetic signs. Thus, this study aims to perform a literature review on the particularities of Horner's syndrome in dogs and cats.