Laryngeal Paralysis (LP) - Bull Terrier

Laryngeal paralysis (LP) is the inability to abduct the arytenoid cartilages during inspiration, resulting in a partial to complete airway obstruction and consequent respiratory distress. Sufficient abduction or opening of the arytenoid cartilages of the larynx during inspiration is essential for breathing. In dogs with laryngeal paralysis (LP), one or both recurrent laryngeal nerves of these muscles become weak (paresis) or paralyzed, the muscles relax, and the cartilages tend to collapse inwards resulting in laryngeal paralysis. The degree of respiratory distress and the clinical presentation are correlating with the fact of unilateral or bilateral disease and the degree of nerve impairment (paresis or paralysis). In Miniature Bull Terrier breed LP is early onset disease with different clinical signs including voice impairment (dysphonia), progressive primarily inspiratory laryngeal stridor, exercise intolerance, life-threatening episodes of breathing difficulties, and in cases of bilateral laryngeal disease syncope and cyanosis. Respiratory distress in affected dogs and can be fatal in severe cases.

Hadji Rasouliha et al. (2019) reported that the imperfect genotype-phenotype correlation suggested a complex mode of inheritance with a major genetic risk factor involving a recessive risk allele. Homozygosity was associated with a 10- to 17-fold increased risk for LP in Miniature Bull Terrier and Bull Terrier breed breeds.

Inheritance: autosomal recessive

Mutation:  RAPGEF6  gene

Genetic test: The method used for testing is extremely accurate and allows complete differentiation between affected animals, carriers and healthy dogs. Testing can be done at any age.