This disease can be prevented. We have a genetic marker and all breeders of breeds prone to CNM should be testing their breeding stock.
I have seen video of a Lab pup with CNM and it is just heart breaking. Here is one if you want to view: Be forwarned it may bring you to tears.
More info here:
“Clinical Symptoms and Histological Signs
At birth, affected puppies are indistinguishable from their control littermates but as from two weeks of age, a progressive significant weight loss is observed. At one month of age, the absence of tendon reflexes is noticed and used as an early and reliable diagnosis. The age of onset of the disabling phenotype varies between 2 to 5 months, with an awkward gait and a decreased exercise tolerance, associated with a generalized muscle weakness. The pup will never recover from this disabling disease.”
Here is more info and on testing your breeding prospects:
Never breed a carrier to a carrier:
Vetgen does the testing for the hereditary gene: