'First Case of Stiff-Horse Syndrome in United Kingdom'.

Stiff-person syndrome is a well-recognised disease in humans, whilst cases of stiff-horse syndrome (SHS) have been rarely reported in the veterinary medicine literature. SHS is a progressive immunomediated disorder of the central nervous system leading to a disturbance of gamma amino butyric acid transmission at the neuromuscular junction in which antibodies are produced against the enzyme glutamic acid decarboxylase. A 6 year-old Irish Sport Horse was presented for investigation of involuntary violent contraction of hindlimb and back muscles triggered by stress. The diagnosis of SHS was made after elevated anti-glutamic acid decarboxylase antibodies titres were detected in the horse's serum. Administration of oral corticosteroids (prednisolone 0.75 mg/kg bwt) resulted in resolution of the clinical signs. However, reoccurrence of clinical signs was observed after the dose of corticosteroids was reduced or the treatment discontinued. To the best of the authors' knowledge this is the first reported case of SHS in United Kingdom. Considering the potential implications on the horses' welfare, further investigation on SHS pathogenesis and treatment are warranted.