Problems associated with the temporomandibular joint (TMJ) of dogs and cats are uncommon; therefore, this joint may sometimes cause uncertainty when an abnormality does arise. Although traumatic dislocations with or without associated condylar fractures are the most common TMJ abnormality, there are a small number of additional pathologic conditions that affect this joint.
Comminuted and intra-articular fractures that can lead to joint arthrosis and ankylosis may be treated with a condylectomy, although it is controversial whether to perform this surgery at the time of trauma or later if healing complications occur. Tape muzzles may be contraindicated in these situations as immobility of the joint may promote ankylosis.
Reported in Bassett Hounds, Dachshunds, Irish Setters and a handful of additional dog and cat breeds, dysplasia is a rare congenital or developmental condition. It generally consists of malformation of the bony structures of the TMJ, and it results in brief to extended periods of intermittent open-mouth jaw locking. Yawning usually precipitates an event.
Obtaining detailed s of the TMJ usually expedites the search for a diagnosis. Extra-oral radiographic technique is used to the TMJ. Multiple views are required to assess the joint. Dorsoventral (or ventrodorsal) and right- and left-lateral oblique views are standard. Some veterinarians find it useful to add an open-mouth view to a series.
Radiographic features of dysplasia consist of flattening of the mandibular condyle and fossa with a hypoplastic or misshapen retroarticular process, a widened irregular joint space with periarticular osteophytosis and an increased obliquity of the articular surface of the mandibular condyle. Immediate treatment for coronoid displacement consists of manually opening the jaw even further to release the coronoid process from the lateral aspect of the zygomatic arch; sedation may be necessary.
Treatment of TMJ luxation normally involves manipulating the displaced bone back into place which has to be done under general anaesthesia. If the joint is unstable after being put back in place then post-reduction stabilisation may be needed using a support muzzle. If there are more complicated factors associated with the luxation (i.e. a concurrent fracture) then that will be dealt with concurrently and may require invasive surgery. The jaw can be stabilised with temporary fixation, wiring or dental acrylic. In severe or chronic cases, removal of the articular process of the mandible may be required (excision arthroplasty). The technical difficulty for this procedure is much greater in the dog compared to the cat and therefore the outcome is less predictable.
If you suspect that your dog has TMJ luxation then you should take it to be seen by your local veterinary surgeon. They will physically examine the animal to assess the jaw but in order to get a true diagnosis and formulate a plan, x-rays will be necessary. Due to the location of the TMJ, plain x-ray can sometimes be hard to interpret and advanced imaging with CT, which provides a 3D x-ray, may be required.
Most of these animals are presented to their veterinarians with the complaint that they are unable to eat normally. You will need to begin by giving a thorough history of your dog’s health, including a background history of symptoms, when the problems first appeared, and whether there have been any previous traumas or injuries involving the mouth or head.
This condition can be very painful, and regular pain relieving drugs may be required until the symptoms have resolved completely. Your veterinarian may also use a feeding tube to give your dog its required nutrients, especially if your dog is unable to take enough food through its mouth alone. Your veterinarian will also brief you on the correct use of the feeding tube at home so that you can take your dog home to recover in relative comfort and quiet.
There are two temporomandibular joints, one on each side of the face, each one working in concert with the other. TMJ plays a pivotal role in the normal chewing process, and is in fact essential for proper chewing, so that and any disease of this joint compromises the ability to make normal mouth movements and chew food. An affected animal will feel pain when closing or opening the mouth, or both. Diseases and disorders of the TMJ are referred to as temporomandibular joint disorders.
X-rays remain a valuable tool in the diagnosis of TMJ disorders, and your doctor will be likely to use this type of imaging to get a better view of the bones and joints in the face. Magnetic resonance imaging (MRI) can be used as well, and can give a better, more detailed view that standard X-ray. If your veterinarian has an MRI machine in the clinic, this may be the recommended technique. If something more severe is suspected, such as infection or tumor, your veterinarian may also take a small sample from the muscle tissue of the jaw so that other diseases that can cause similar symptoms can either be confirmed or ruled out.
The temporomandibular joint is the jaw joint, the hinged point in the jaw that is formed by two bones, named the temporal and mandible bones. The temporomandibular joint is also frequently referred to as simply TMJ.