My six-month old puppy started having pain around its mouth when trying to eat. His jaw also looks funny. The veterinarian diagnosed the puppy's condition as CMO. What is that?
CMO refers to craniomandibular osteopathy, also called "lion jaw" because of the deformed shape the jaw often acquires in affected dogs. CMO is an abnormality of skeletal maturation where certain bones, principally the bones of the skull and jaw, over- develop and cause pain, especially when eating. Growing puppies four to eight months of age may develop this skeletal thickening. CMO may even lead to fusion of the temporomandibular joint, which is the point of articulation of the jaw. This makes it extremely difficult for the affected dog to open its mouth. The bony proliferation may spontaneously regress to a variable extent at eight to 12 months of age. Veterinarians believe there is a heritable, genetic link in CMO. This is suggested by the predisposition of Scottish terriers to develop the disease, as well as West Highland white terriers. The latter breed probably inherits the tendency to develop CMO as an autosomal recessive trait, in which both parents must carry the gene in order to have an offspring with the disease. Certain other terrier breeds, including Cairn and Boston terriers, also are at increased risk. Some non-terrier breeds have a tendency to develop CMO with greater frequency than other dog breeds. These include Dobermans, Great Danes, English bulldogs, boxers and Irish setters. Diagnosis of CMO is based on clinical signs, physical examination, bloodwork and radiographs (x-rays). Affected puppies may have increased blood levels of alkaline phosphatase, an enzyme, and phosphate. Certain blood proteins associated with bone proliferation may also be too high or too low. No definitive treatment exists for CMO. Anti-inflammatory drugs may reduce clinical signs of head or jaw pain and fever, but will not likely slow the progression of the disease. Soft, high-quality food may make eating easier. To maintain adequate nutrition, some puppies will need surgically placed feeding tubes. These are typically left in place and used until sufficient time has passed to evaluate how extensive and debilitating the disease will be. Although the prognosis is generally guarded, it will ultimately depend upon the disease's severity and the affected puppy's ability to eat normally. If pups in a litter are affected with CMO, it seems prudent that the dam and sire not be allowed to breed further.
01/29/09
