Muscular Dystrophy is an x-linked recessive, progressive muscle wasting disease seen most commonly in the Golden Retriever but also in other breeds including the Cavalier King Charles Spaniel. It is considered inherited with the condition generally seen in males though females may be carriers (females would have to get the affected gene from both parents to be symptomatic). There is a similar form also found in human boys.
It is caused by the muscle tissue’s cytoskeletal impairment to properly create the functional protein dystrophin and dystrophin-associated protein complex. Dogs who carry this defective gene for the protein dystrophin will be unable to form normal muscle and become progressively weaker until there is cardiac and respiratory impairment.
Symptoms generally start to present around 6-10 weeks. Some of the symptoms are:
- Gait abnormalities such as a shuffling gait or bunny hop
- Muscle spasms
- Muscular weakness
- Muscle wasting
- Lack of interest in playing/exercise
- Difficulty swallowing due to an enlarged tongue
- Inability to completely open jaw
- Excessive drooling
- Difficulty breathing
- Difficulty moving tongue
- Limb deformity
As this disease can mimic some others, a muscle biopsy is necessary to confirm. There is no cure or treatment, though the use of steroids can slow down progression. Prognosis is generally not good with some dogs living only days and others up to a couple of years. There are some new treatments for this condition under study which are looking hopeful; one is stem cell replacement (injecting the dog with cells from a healthy dog) and the other is called “exon skipping” which tries to trick the body into skipping over the bad segments in the affected genes.
A PCR based DNA test is now available for the type of Muscular Dystrophy seen in Cavaliers.