CMO is a non-cancerous growth of bone on the lower jaw bone.  Usually, CMO affects the jawbone bilaterally, but this is not always the case.  The first of the clinical signs appear between three and four months of age, when the affected puppy shows discomfort while chewing, or when the puppy's mouth is being examined.  An experienced breeder and/or veterinarian can detect the condition through palpation of the area: they can feel the dense, hard, and rough surface that is caused by the disease.  Accurate diagnosis can be made, when at an appropriate age, x-rays are taken to make the appropriate determination.  Other clinical signs of CMO are that the puppy may run a fever and be lethargic, the site itself may feel warm and display signs of inflammation.  Severely affected puppies may be unable to open its mouth, however, the mild cases may be mistaken for teething problems or symptoms of a viral infection.  Treatment by a veterinarian is important to alleviate discomfort to the puppy, and to prevent any infection that may occur and further impair the dog.
     It is important that breeders realize that this disease can be passed on to future generations by breeding treated animals.  Even though the treated animal no longer displays clinical signs of this disorder, he/she is still a carrier of the gene for this genetic fault, thereby creating a genetic liability in the bloodline of the breed.  This is also known as an autosomal recessive trait.
 

     Following is a short explanation of how an autosomal recessive trait is passed from one set of parents to the offspring.
     The capital "D" represents the dominant gene, which in this case, is free, or clear, of the disorder.  The lower case "r" is the recessive characteristic, which in this case is the disorder, CMO.

If the sire and dam of the puppy are not carriers of a disease, for our purposes CMO, than all the "get" from their breeding will be free of the disease.