Centronuclear Myopathy (or Canine Muscle Myopathy, CNM)
This is the third installment in my three part series on health concerns affecting Labrador retrievers. The first was on Hip Dysplasia, the second was on Exercise Induced Collapse and this one will cover what I thought was Canine Muscle Myopathy. I have learned a lot in my research for these three columns and one of those was the fact that although it is often called Canine Muscle Myopathy, its real name is Centronuclear Myopathy or CNM for short.
These are big words for a dog guy and overwhelming for many potential puppy buyers. There are many different myopathy's that affect Labradors. Many are just an unfortunate function of dog health and there is little that can be done to avoid them at purchase time but this is one that can avoided by proper breeding procedures and is one that every puppy buyer better have a good grip on before they lay out good hard cash to make a puppy purchase.
So just what is Centronuclear Myopathy (CNM)? It is a disabling disease that affects Labradors from all over the world. Countries like the United States, Canada, Argentina, South Africa and Europe all have reported cases of this disease. The outcomes seem to be identical regardless of where they are reported. At birth the affected puppy is undistinguishable from its litter mates. Symptoms become visible at 2–5 months of age. Most puppies go home to the new owners at around eight weeks.
During this time (2–5 months) weight loss is evident and a general deterioration of muscle control becomes evident. Puppies exhibit an awkward gait and intolerance to any kind of exercise. The condition will worsen to an almost complete loose of muscle control. There are videos on YOUTUBE that show dogs with this condition and they are almost enough to make you cry. Afflicted dogs will never recover and in most cases they are put to sleep. If the dog does manage to survive for very long they suffer from significant respiratory difficulties due to condition. To see a dog with this condition would make you think that this dog had been on the loose in a war zone for six months with almost no food or water. There is nothing pretty about Centronuclear Myopathy (CNM).
Avoiding this condition in the first place is the only way to deal with the problem. Just like the condition EIC that I covered last week this condition can be avoided with proper attention to the status of the parents. This status can now be determined with a blood test that looks for mutated genes. If both parents are CNM clear than the puppies will be clear and no problems will result. Just like with EIC, if one parent is a carrier and one is clear than 50% of the puppies will be a carrier and 50% will be clear. Being a carrier will not result in the CNM affliction. Carriers show no signs. They just have the ability to pass on the defect to their offspring if proper precautions are not taken.
What this means is that breeding Labrador puppies is more than getting two AKC registered dogs of opposite sexes in the same room at the right time. It requires the breeder to spend a very substantial investment in time and money to get their breeding stock checked for three important genetic defects before any breeding takes place. They need to have the hips x-rayed on dogs that are at least two years of age. They need to get a certificate of a passing grade from the OFA. If they pass this requirement they need to have both the EIC and the CNM test done to insure that at least one parent is tested CLEAR for both of these diseases. Both parents with an all clear on both tests are better but not a requirement. Remember that carriers of EIC and CNM will not show signs or suffer from these conditions. Only dogs that are consider affected (2 mutated genes, one from each parent) will live less than satisfactory lives in a hunting home and most pet homes for that matter.
The next time you price a puppy and the seller tells you the price is $150, ask about these three issues. Cheap puppies will come with few assurances. I would rather pay $650 for a puppy that I know is not affected by EIC and CNM and has parents with good hips than the cheaper priced one that has a pretty good chance of heartbreak later.
I love my dogs. All four of them lay on the living room rug as I scratch them behind the ears. We hunt and train together as often as we can. I owe them the best dog quality of life that I can deliver and they hunt as hard as they can to say thanks for that life. If you as dog buyer don't do everything in your power to wipe out these serious health issues by mandating (with your pocketbook) your breeder do well researched breeding backgrounds and by making sure that whatever breeding that you may do with your own dog does not pass on these avoidable health issues then maybe you should consider making a different purchasing decision. Maybe you should consider buying a cat instead.