Genetic basis of CMSD in Chinese Crested dogs - is caused by a mutation (c.128+1_128+4delGTAA) in the SERAC1 gene located on chromosome 1. This mutation leads to degeneration of neurons in the midbrain and loss of cerebellar cells. The disorder is inherited in an autosomal recessive manner: affected dogs have two copies of the mutated gene, carriers with one copy are asymptomatic but can pass the mutation on. Genetic testing is available to identify carriers and affected dogs, enabling breeders to avoid carrier-to-carrier matings.
Pathophysiology - The mutation causes progressive degeneration of the motor system, particularly affecting cerebellar neurons responsible for coordination and balance.This neuronal loss leads to movement disorders resembling juvenile Parkinson’s disease in humans.Cerebellar atrophy and loss of Purkinje cells are observed.
Complications - Onset typically occurs between 3 to 6 months of age. Early signs include: Unnatural head tremor, especially noticeable when the dog attempts to eat (intention tremor). Cerebellar ataxia (loss of coordination). Goose-stepping gait (hypermetria) predominantly affecting forelimbs. As the disease progresses (6 to 8 months): Increasing frequency of falls. Festination gait (hurried, irregular steps) with dysmetria. Dogs become unable to stand or move straight, adopting a hunched posture. Severe postural instability and akinesia (loss of voluntary movement). Most affected dogs require euthanasia by 13 to 18 months due to severe disability.
Why This Matters to Breeders and Vets - Identification of carriers through DNA testing allows breeders to avoid mating two carriers, preventing affected puppies. Early recognition by veterinarians allows supportive care and counseling of owners on prognosis. The disease is progressive and currently untreatable; supportive care is the main management.
Summary - Canine Multiple System Degeneration in Chinese Crested dogs is a fatal autosomal recessive neurological disease caused by a SERAC1 gene mutation. It manifests as early-onset tremors, cerebellar ataxia, and progressive movement disorders leading to severe disability and euthanasia within the first two years of life. Genetic testing supports control and reduction of CMSD through informed breeding practices.