title: Laryngeal paralysis: a study of 375 cases in a mixed-breed population of horses.
abstract: Referred cases (n = 375) of laryngeal paralysis (1985-1998) from a mixed-breed equine population included 351 (94%) cases of recurrent laryngeal neuropathy (RLN) (idiopathic laryngeal hemiplegia) and 24 cases (6%) of laryngeal paralysis from causes other than RLN. Laryngeal movements were classified endoscopically into one of 6 grades, in contrast to the usual 4 grades. The RLN cases had a median grade 4 laryngeal paralysis, of which 96% were left-sided, 2% right-sided and 2% bilaterally affected. RLN cases included 204 (58%) Thoroughbred, 96 (27%) Thoroughbred-cross, 23 (7%) draught, 16 (5%) Warmbloods and 10 (3%) other breeds, including only 4 (1%) ponies. The median age of RLN cases at referral was 6 years (range 2-12) and their median height was 170.2 cm. The work of RLN horses included National Hunt racing (42%), flat racing (1%), hunting (19%), eventing (16%) and miscellaneous work (22%). Reported presenting signs in RLN-affected horses included abnormal exercise-related respiratory sounds in 90% and reduced exercise tolerance in only 64%. However, many horses were referred before their exercise tolerance could be fully assessed. Forty percent of the RLN cases had intercurrent disorders, including 10% with additional upper respiratory and 7% with lower respiratory tract diseases. The 24 nonidiopathic RLN cases included 12 with bilateral laryngeal paralysis, 11 (92%) of which were ponies. Bilateral laryngeal paralysis occurred with hepatic encephalopathy in 7 cases and following general anaesthesia in 2 cases. The 12 cases of acquired unilateral laryngeal paralysis included 7 caused by guttural pouch mycosis.
authors.affiliation: The Wellcome Trust Centre for Studies in Comparative Respiratory Medicine, The University of Edinburgh, Easter Bush Veterinary Centre, Easter Bush, Midlothian, Scotland.
authors.forename: P M
authors.initials: PM
authors.lastname: Dixon
authors.forename: B C
authors.initials: BC
authors.lastname: McGorum
authors.forename: D I
authors.initials: DI
authors.lastname: Railton
authors.forename: C
authors.initials: C
authors.lastname: Hawe
authors.forename: W H
authors.initials: WH
authors.lastname: Tremaine
authors.forename: K
authors.initials: K
authors.lastname: Pickles
authors.forename: J
authors.initials: J
authors.lastname: McCann
mesh_terms: D000818:Animals; D003937:Diagnosis, Differential; D005260:Female; D006734:Horse Diseases / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D006736:Horses; D007828:Laryngoscopy / Q000662:veterinary; D008297:Male; D010805:Physical Conditioning, Animal; D011446:Prospective Studies; D012008:Recurrence; D012009:Recurrent Laryngeal Nerve / Q000503:physiopathology*; D012135:Respiratory Sounds / Q000209:etiology / Q000503:physiopathology / Q000662:veterinary; D012189:Retrospective Studies; D014826:Vocal Cord Paralysis / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000662:veterinary*