Larynx paralysis is a disease in the Miniature Bull Terrier and some other small dog breeds, which is scientifically not well understood. Larynx paralysis leads to difficulties in breathing, especially during physical activity, and may cause death by suffocation in severe cases. Larynx paralysis may require surgery to relieve the difficulties in breathing. We identified a genetic risk factor for larynx paralysis in Miniature Bull Terriers. Genetic testing has become available.