EquineReview

In contrast with cats, dogs and humans, facial nerve paralysis is poorly documented in equids. In this retrospective case series Boorman and colleagues in J Vet Intern Med (2020; 34:1308–1320. https://doi.org/10.1111/jvim.15767) describe the clinical features of 64 horses presenting with facial nerve paralysis, excluding postoperative cases. Unlike in other species the most common aetiology was trauma, with true idiopathic cases being unusual, and the majority (92%) of cases presented with unilateral disease. Central nervous system disease was the second commonest cause, emphasising the need for a thorough clinical and neurological examination in such cases. Over 50% of horses were unable to blink and required specific ocular therapy. Twenty five percent of horses were euthanased but only one was directly as a result of the facial nerve paralysis, and of the surviving animals 72% showed complete resolution of paralysis, with a further 14% showing partial improvement. Weaknesses of the study included a lack of advanced imaging (computed tomography) in the majority of cases and low numbers for specific diseases resulting in facial nerve paralysis, making it hard to draw valid conclusions with regards to prognostic indicators.