Genetic basis of Cleft lip and palate in Nova Scotia Duck Tolling Retrievers - is a hereditary, autosomal recessive condition. There are two primary genetic mutations identified in this breed causing different but related forms: A mutation in the ADAMTS20 gene causes cleft lip/palate and syndactyly (CLPS) — a birth defect characterized by cleft lip, cleft palate, and fusion of the middle toes (syndactyly). A mutation in the DLX6 gene (specifically an insertion of a LINE-1 element) causes a more severe cleft palate (CP1) often accompanied by shortening of the lower jaw (mandibular brachygnathia) and nasal abnormalities. Both mutations are inherited autosomal recessively, meaning affected puppies have two copies of the mutated gene.
Pathophysiology - Puppies affected by cleft palate have an opening in the roof of the mouth, which causes difficulty nursing because milk can enter the respiratory tract. This leads to frequent aspiration pneumonia, a common and potentially fatal complication. Some affected puppies also have mandibular brachygnathia, an abnormally short lower jaw impacting feeding. The ADAMTS20 mutation’s additional hallmark is syndactyly (fused toes). Both genetic defects affect embryologic development of facial bones and soft tissues.
Complications - Feeding difficulty and poor weight gain due to inability to suckle effectively. Aspiration pneumonia, which is a leading cause of death in affected puppies. Respiratory infections. Possible secondary complications from mandibular brachygnathia that impair feeding further. Veterinary intervention is often required for feeding support or surgery.
Why This Matters to Breeders and Vets - Breeders: Identification of carriers through genetic testing is critical to prevent mating of two carriers, as this produces 25% affected puppies per litter. Vets: Early diagnosis supports management strategies. Knowing a puppy's genetic status helps in breeding counseling and long-term disease control in the breed. Awareness of the condition improves breeding decisions and helps reduce incidence in the population.