Masticatory muscle myositis (otherwise known as MMM) is a disease in dogs that affects the chewing areas of the face - mastication. Normally, this disease affects rather large dog breeds such as German Shepherds. It has not been seen to affect other animals, such as cats or humans.
The basic way of explaining the causes of this disease is to say that the immune system of the dog basically attacks it's own muscles. There are both chronic and acute forms of this and the chronic form tends to be more common.
There are certain symptoms associated with MMM in dogs, and the main one is swelling in the muscles in the face, particularly in the forehead and other facial muscles. A fever is also common and this is very often combined with a reluctant attitude to food. This is because the chewing motion is painful for the dog and therefore he or she could whimper when moving the jaw open and shut, especially when eating and chewing.
Dogs with masticatory muscle myositis tend to salivate more than usual, and although dogs tend to do this more than any other animal anyway, it may be quite hard to pinpoint this as a symptom. MMM is also a disease associated with bulging of the eyes, and it maybe difficult for the dog to open its mouth.
In the worst case scenario of a dog with masticatory muscle myositis, the dog may require being fed through a feeding tube, however, with early diagnosis, steroids can be given to suppress the disease.
Diagnosis of this disease in dogs tends to be quite easy, and generally follows a physical examination of the dog, particularly in the facial area. Blood samples may be taken and X-Rays of the skull and also of the dentures may be required.
Once at home, after Veterinarian care, it is important to continually check your dog for to keep a close eye on its response to treatment and to see if the condition is getting any worse. In so many cases with dogs with MMM, long term and even therapy for it's entire lifetime may be required. Only feeding the dog a diet consisting of soft foods may be necessary for some time, until it is obvious that the dog can handle solid food stuffs again. It is also highly advisable to keep your dogs away from many toys, especially ones designed for chewing, and especially bones!
Unfortunately, the disease Masticatory muscle myositis isn't really caused by anything other than the breed of dog or age. There are no methods you, as an owner, can take to prevent it from happening and the only way to ensure lifelong happiness for your Vet, especially trying to avoid situations like this, is to take your pet for regular check ups with your Vet and also take them to the Vet if there are any unusual signs of behaviour.