Prevalence of laryngeal paresis in dogs undergoing general anaesthesia.

OBJECTIVE To estimate the prevalence of laryngeal paresis within a selected population of dogs and identify some of the distinguishing characteristics of affected dogs. DESIGN A prospective study involving laryngoscopic examination of 250 dogs. PROCEDURE The laryngeal movements of 250 dogs undergoing general anaesthesia were observed. The severity of laryngeal paresis in these dogs was graded (0 = normal laryngeal movements, 4 = bilateral laryngeal paralysis). The following information was also recorded for each dog: age, sex, weight, breed, condition score, anaesthetic protocol, clinical suspicion of disease and observer. RESULTS Twenty five percent of the dogs examined had some degree of laryngeal paresis. Affected dogs were significantly older than unaffected dogs (P < 0.001). There was a trend for the severity of laryngeal paresis to increase with age. There was no difference between the sexes. Dogs with laryngeal paresis were significantly heavier than normal animals (P < 0.02). Overweight animals had a significantly higher laryngeal grade than those with a normal condition score (P < 0.05). Labrador Retrievers and Rottweilers had a significantly higher risk of having laryngeal paresis (P < 0.05). Clinical suspicion was found to have high diagnostic value. An intra-class correlation coefficient for inter-rater reliability between the two observers was 0.95. CONCLUSIONS Laryngeal paresis had a high prevalence in the animals surveyed and was strongly associated with age and breed. The results of this study are consistent with the concept of a progressive degenerative disease with a breed susceptibility. Clinical suspicion for the presence of the disease was a reliable indicator. The grading system used had a high degree of inter-observer agreement.