The first clinical signs of CMO typically appear at the age of 4 to 7 months. The skull bones and especially the mandible seem enlarged due to swelling and thickening of the jaw. The condition causes pain, which manifests in drooling, difficulties in eating, and unwillingness to open mouth. In addition, recurrent fever may be associated with CMO. Bone changes may disappear once the dog's growth period is finished, but before that multiple episodes of fever and pain may occur.

Treatment is pain management, supportive care, and symptomatic depending on the severity of the dog's clinical signs.

There are many responsibilities to consider when breeding dogs. Regardless of test results it is important that your dog is in good general health and that you are in a position to care for the puppies if new responsible owners are not found. For first time or novice breeders, advice can be found at most kennel club websites.

This mutation is considered a risk factor for Craniomandibular Osteopathy, and dogs with one or two copies of the mutation are at increased risk. However not all dogs with one or two copies of this mutation will show signs of disease. Use of dogs with one or two copies of the disease mutation is not recommended, as there is a risk that the resulting litter will contain affected puppies. For example if a dog with one copy of the CMO mutation is bred with a clear dog with no copies of the CMO mutation, about half of the puppies will have one copy (carriers) and half will have no copies of the CMO mutation. Please note: It is possible that disease signs similar to the ones caused by the CMO mutation could develop due to a different genetic or clinical cause.