Canine Multiple System Degeneration Chinese Crested Type CMSD
Canine multiple system degeneration Chinese Crested Type (CMSD) is an early onset autosomal recessive movement disease. It is a progressive inherited neurological disease which affects Kerry Blue Terriers (KBT) and Chinese Crested Dogs (CCD). This disorder is clinically and pathologically indistinguishable between Chinese Crested dogs and the Kerry Blue Terriers. The CMSD was for the first time recognized in the 1940’s in the Kerry Blue terrier dog and is commonly called PNA among the Kerry Blue terrier breeders.
The first clinical signs in the affected dogs are recognized by a tremor of the head, which is most noticeable during dog’s attempt to eat. The first symptoms start developing along with cerebellar ataxia already at 3–6 months of age. At this early stage, the affected dogs will exhibit a goose stepping gait and infrequent falls. In case of MRI examination, a cerebellar atrophy can be seen. Also, in case of histopathological examination, loss of the Purkinje cells in the cerebellum is prominent.
By 6-8 months of age, the nature of movement disorder changes and falls become more frequent. Gait changes to festination with dysmetria. The dog starts shifting their body weight, until the point where they begin to stumble forward. They can run for a short period of time, until they do not fall.
By the time of 12-18 months of age, the dog’s instability is severely developed and the dog is incapable of making any voluntary movement, it becomes akinetic. Attempt of standing independently ends in falling. The disease affects dog’s life-length and most dogs die due to disease complications or are euthanized by 18 months of age. No matter the severity of disease, affected dogs show normal mentation and social behavior.
The canine multiple system degeneration Chinese Crested type, as well as Kerry Blue terrier type, is caused by a mutation in the SERAC1 gene, which is located on the chromosome 1. Primary symptom of the affected dogs is the movement disorder, caused by motor system degeneration. The motor system degeneration occurs due to degeneration of neurons in one of the midbrain region and loss of cerebellar cells. CMSD course and symptoms appear very similar to Parkinson’s disease in humans. The Parkinson’s diseas is caused by a mutation in a gene that is localized in same gene region as the SERAC1 gene.