Genetic basis of Acral Mutilation Syndrome - is an autosomal recessive genetic disorder affecting certain dog breeds, including Spaniels (such as English Springer Spaniels and French Spaniels) and Pointers (such as German Shorthaired Pointers and English Pointers). The condition is caused by a mutation in the GDNF-AS gene (located on chromosome 4, with variant Chr. 4 g.70875561 C>T), which affects sensory nerve development and function. Dogs must inherit two copies of the mutated gene (one from each parent) to develop AMS; carriers with only one copy do not show symptoms but can pass the mutation to offspring. This mutation leads to peripheral sensory neuropathy, primarily impairing the sensation of pain in the distal extremities (paws and toes).
Pathophysiology - The mutation causes malfunction of peripheral sensory nerves, resulting in loss of pain sensation (acral analgesia) in the feet and toes. Affected dogs cannot feel pain in these areas and therefore engage in excessive licking, biting, and self-mutilation of their paws. Despite the loss of pain sensation in the distal limbs, motor skills and spinal reflexes typically remain normal. Symptoms usually begin to appear between 3 to 12 months of age.
Complications - Progressive self-inflicted injury leads to: Bleeding, ulceration, and infection of footpads and toes. Tissue loss and mutilation of claws, digits, or footpads. Paronychia (infection around the nails). Painless fractures in severe cases. Multiple feet may be affected.The condition can cause chronic pain from secondary infections and disability in severe cases. Diagnosis requires differentiation from other causes of paw licking or neurological disorders.
Why This Matters to Breeders and Vets - Breeders need to identify carriers and avoid breeding two carriers to prevent producing affected puppies. Veterinarians must differentiate AMS from other causes of paw injury and advise on symptom management. Awareness and genetic testing help reduce the spread of AMS in susceptible breeds, which include Spaniels (English Springer Spaniel and French Spaniel), Pointers, German Shepherds, Labrador Retrievers, and others. Early recognition allows for better clinical management and improved quality of life for affected dogs.
Summary - Acral Mutilation Syndrome is an autosomal recessive sensory neuropathy caused by a mutation in the GDNF-AS gene that results in loss of pain sensation in distal limbs, leading to self-mutilation of paws in affected dogs. It primarily affects Spaniel and Pointer breeds, among others. Genetic testing and responsible breeding practices are key to preventing the disease, while veterinarians play a critical role in diagnosis and management.