HEMIPLEGIA-LARYNGIS IN HORSES - AN EXAMINATION ON STALLIONS, MARES AND THEIR OFFSPRING

Laryngoscopic examination during sedation was performed on 24 Stallion s and on their offspring (240 foals and 474 adult horses). Additionall y the dams (n = 308) of 35 foals and 216 horses were examined. With th e bilateral comparison of the arytaenoid movements the function of the abductory and adductory laryngeal muscles were evaluated and the left abductory dysfunction (idiopathic laryngeal hemiplegia, ILH) was divi ded into six degrees. The incidence and degree of ILH depended on age and the occurrence of the same dysfunction in the parents. Foals suffe red in significantly lower number (24.7 per cent) than adult horses (4 9.7 per cent). The progeny of unaffected parents suffered significantl y less from ILH (8.9 per cent of the foals, 39.6 per cent of the adult offspring) than did comparable progeny of affected parents (41 per ce nt of the foals, 60.9 per cent of the adult offspring). There was no c orrelation between the occurrence of ILH and sex. 120 horses were exam ined laryngoscopically and during work to get an information about the correlation between a visible ILH and the appearance of a typical ins piratory noise. 54.3 per cent of the horses with ILH had a typical ins piratory noise. 80.9 per cent of the horse with a typical inspiratory noise showed ILH.