Dysphagia-associated muscular dystrophy: a familial trait in the bouvier des Flandres.

Among a group of dysphagic dogs the bouvier des Flandres was overrepresented. The results of a clinical examination, contrast videofluorography and electromyography of the pharyngeal, laryngeal and oesophageal muscles were similar in all the bouviers, and a histological examination of tissues from 10 of them revealed muscular dystrophy as the cause of the dysphagia. A study of the affected dogs' pedigrees revealed that they were descendants of one closely related group of ancestors, and that the inbreeding levels for this ancestor group were higher than in a control population of 136 bouviers. The homozygosity due to inbreeding for this ancestor group was higher in the affected dogs than in the control dogs, but the homozygosity due to all other ancestry was equal in the two groups. The relative risk of developing dysphagia-associated muscular dystrophy was up to 16 times greater in these bouviers, depending on the level of inbreeding for the closely related ancestor group.