Genetic basis of DAMS in Labrador Retrievers - is caused by an autosomal recessive nonsense mutation (c.388C>T, p.R130) in the EHBP1L1 gene*. This mutation results in a premature stop codon, truncating about 90% of the EHBP1L1 protein, which plays a key role in actin cytoskeletal organization and intracellular trafficking. The mutation is homozygous in affected dogs and very rare in the breed population.
Pathophysiology - The syndrome presents with marked microcytosis (small red blood cells), inappropriate metarubricytosis (immature red blood cells in circulation), muscle atrophy, and pelvic limb weakness. Associated muscle pathology is consistent with congenital polymyopathy featuring excessive variability of muscle fiber size and centralized nuclei. Unlike the similar syndrome described in English Springer Spaniels, Labrador Retrievers generally do not show cardiomyopathy or megaesophagus
Complications - Progressive muscle atrophy that impairs mobility. Anemia that may affect quality of life. Unlike English Springer Spaniels, cardiomyopathy and megaesophagus are not commonly observed. Lifespan and overall prognosis depend on disease severity and management.
Clinical Presentation - Clinical signs typically appear in young dogs, with observed muscle weakness and atrophy, particularly of the pelvic limbs. Blood abnormalities such as anemia and atypical erythrocyte morphology are detectable even before clinical signs of muscle weakness emerge. Lack of cardiac involvement distinguishes the Labrador Retriever form from the English Springer Spaniel form
Why This Matters to Breeders and Vets - The discovery of EHBP1L1 mutations as the cause of DAMS provides insights into disease mechanisms and may inform diagnosis and future therapies. Genetic testing facilitates identification of carriers and affected dogs, enabling informed breeding decisions to reduce disease incidence. Understanding breed-specific clinical differences improves veterinary management.