Temporomandibular Joint Disorders in Dogs

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.

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.

Though these disorders can occur in any dog breed, certain breeds like basset hounds are more predisposed to TMJ disorders. Open-mouth mandibular locking has been reported in Irish setters and basset hounds.

Symptoms and Types

• Difficulty opening/closing the mouth
• Mandible bone may be out of place and visible form the side of the face (deviation of the mandible bone)
• Pain when chewing food
• Vocalizing, whining while trying to eat
• Loss of appetite

Causes

• Injury or trauma causing fractures to the joint
• Stress in joint after carrying heavy objects by mouth

Diagnosis

 

Most of these animals are presented to their veterinarian's 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.

After taking a detailed history, your veterinarian will conduct a complete physical examination on your dog, examining the mouth, bones and the joints in the mouth. Laboratory tests will include a complete blood count (CBC), biochemistry profile, and urinalysis. The results of these tests are often found to be normal, especially if no other concurrent disease is present.

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 image 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.

Treatment

Treatment for TMJ disorders is two-fold and is aimed at eliminating or altering the underlying cause as well as treating the symptoms. In case of complete dislocation of the TMJ, your veterinarian will try to repair it by placing an object at a specific site close to the joint, and gently closing the mouth with a push in order to reduce the dislocation. If this method does not work well or the problem becomes chronic, surgery may be required to correct the defect. Pain killers will also be given to reduce the pain related these disorders. Muscle relaxing drugs can also be prescribed, if need be, to reduce the muscle tension created as a result of the TMJ disorder.

Living and Management

After surgery, your dog may feel sore and will need proper rest in a quiet place, away from other pets and active children. You might consider cage rest for a short time, until your pet can safely move about again without overexertion. Your veterinarian will also prescribe a short course of pain killers until your pet has fully recovered, along with a mild course of antibiotics, to prevent any opportunistic bacteria from attacking your pet. Medications will need to be given precisely as directed, at the proper dosage and frequency. Keep in mind that over dosage of pain medication is one of the most preventable causes for death in household animals.

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.

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