Masticatory Muscle Myositis Average Cost

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What are Masticatory Muscle Myositis?

German Shepherd Dogs and Cavalier King Charles Spaniels are predisposed to masticatory muscle myositis. Difficulties such as swallowing, and therefore, eating and drinking can lead to serious consequences for your pet. If your dog is showing signs of having jaw discomfort, take him to the veterinary clinic for an evaluation.

The masticatory muscles are used in chewing. They include the jaw muscles and the muscles of the temples. Therefore, masticatory muscle myositis is inflammation of the muscles in the jaw and temple. It affects the trigeminal nerve and can lead to atrophy of the muscles and dogs may have a dropped jaw that cannot stay closed.

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Symptoms of Masticatory Muscle Myositis in Dogs

The symptoms of masticatory muscle myositis can vary depending on the muscles that are affected. If you notice any of these symptoms contact your veterinarian for an appointment to have a full assessment done on your dog.

  • Swelling of the muscles on the top of the head
  • Progressive muscle loss
  • Difficulty moving the jaw
  • Difficulty drinking
  • Difficulty eating or picking up food
  • Unable to open the mouth
  • Eyes look sunken
  • Eyes look protruding
  • Stiff movements
  • Weakness
  • Regurgitation of food and water
  • Difficulty swallowing
  • Difficulty breathing

Causes of Masticatory Muscle Myositis in Dogs

Masticatory muscle myositis can be caused by several things. 

Infection or Virus

Some form of an infectious agent, parasite or virus within the muscle can cause inflammation within the masticatory muscles. 

Abnormal Immune Reaction

An abnormal immune reaction of the body against the muscle is known as immune-mediated myositis. The body produces antibodies that will target parts of the masticatory muscles. This will cause inflammation.


Inflammation within the masticatory muscles can develop as pre-cancerous and then turn into cancer. Cancer found within the body can cause an immune reaction, causing masticatory muscle myositis. This is known as a paracancerous effect.

Diagnosis of Masticatory Muscle Myositis in Dogs

Dogs that have been diagnosed with masticatory muscle myositis produce antibodies against the 2M muscle fibers. There is a blood test that was developed at the University of California at San Diego that will test for these antibodies. 

A biopsy from the temporalis muscle is also recommended to determine the severity of masticatory muscle myositis. There is scarring in the muscle and by examining a biopsy of the muscle, it can be determined how far the disease has progressed and assess your dog’s ability to respond to the recommended treatment.

Treatment of Masticatory Muscle Myositis in Dogs

Your veterinarian will prescribe a treatment plan that is aimed at attempting to counteract the body’s immune system response by suppressing the immune system with immunosuppressant medications. A dose of prednisone, a steroid, is also a common part of the treatment plan. 

The short-term treatment plan will be put in place to return your dog’s immune system to normal by using aggressive medications and high doses. Once the disease is being controlled, the medications are slowly reduced. The long-term goal is to eventually get your dog completely off all medications. Most cases, however, require a continual use of a low dose medication. 

Physical therapy may also be required depending on the severity of the disease. Physical therapy will encourage proper chewing and swallowing. Never force your dog’s jaws open.

Severe cases of masticatory muscle myositis may require surgery to remove a portion of the front jaw, allowing your dog to be able to lap water and food. While surgery may give you more time with your dog, it is a last resort option and the prognosis is extremely guarded.

Recovery of Masticatory Muscle Myositis in Dogs

With early detection, masticatory muscle myositis can be treated successfully. Be sure to follow the treatment plan that your veterinarian prescribes for your dog to ensure recovery. All medications must be given as prescribed, if you notice any side effects, contact your veterinarian immediately.

Return to your veterinarian for all follow-up visits and post-treatment testing to make certain that the disease is being well controlled. Your veterinarian may adjust the medications being given as the treatments progress. 

Early detection of masticatory muscle myositis is important to a good prognosis. Dogs requiring surgery because of severe muscle scarring will have a guarded prognosis.

Masticatory Muscle Myositis Questions and Advice from Veterinary Professionals

Labrador Retriever
6 Years
Mild condition
0 found helpful
Mild condition

Has Symptoms

Sunken eyes
Sunken head
Messy drinking
Difficulty picking up food
Jaw hanging open

My 6 year old Lab has been spilling water when he drinks recently, and has had his jaw hanging open slightly. My vet diagnosed it as trigeminal neuritis which she said should clear up in a few weeks. However, today I noticed his eyes are getting more sunken in, and his head is sunken behind his eyebrows. This led me to suspect MMM. I will take him back to the vet in a month if his jaw doesn't seem any better, but am I hurting his chances of recovery by doing this if it turns out to be MMM?

Dr. Michele King, DVM
Dr. Michele King, DVM
659 Recommendations
Thank you for your email. If Rolo seems to be deteriorating, it would be better to have him seen sooner rather than later. MMM is a difficult disease to diagnose and often requires a biopsy. I'm not sure if he is on any medications at this time, but he may need to be. I hope that he recovers well.

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Labrador Retriever
13 years
Mild condition
0 found helpful
Mild condition

Recently and quite sudden he cannot grab his food and causes a mess while eating.. He tries to grab his food so hard that he tired and lay down panting. He was recently on steroid and antibiotic and slightly anemic due to a growth on his tail which needed minor surgery with local anesthetic .. Could it be due to the medication he was on that causes this jaw problem i.e.MM? Could it be the side effect of the steroid?

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
2129 Recommendations
Corticosteroids are the indicated treatment of masticatory muscle myositis; I don’t think it is connected to the treatment he was receiving. Difficulty to open the mouth may be caused may masticatory muscle myositis, temporomandibular joint ankylosis, nerve injury, dental issues among other causes. I would recommend returning to your Veterinarian for an examination to see what the underlying cause is; until then, at least ensure that Scout is able to drink water. Regards Dr Callum Turner DVM

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Golden Retriever
Moderate condition
0 found helpful
Moderate condition

My 5 year old Golden Retriever Gracie just started to not be able to close her mouth all the way, she cannot chew and when she drinks water it goes everywhere. She has all the symptom of MMM and I am heartbroken. This just started 4 days ago. I brought her to the vet today and they took some blood and I won't get the results until tmrw. Gracie didn't eat the treat they tried to give her so they didn't see what I see at home....her inability to chew. I am praying I caught this early enough to get a good prognosis. The thought of giving her steroids kills me. She is the sweetest most gentle little lady. I am so scared!


Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
2129 Recommendations
Steroids are a necessary in medicine, but they are not as bad as people think and they are nothing like the steroids which are abused by bodybuilders. The use of corticosteroids (not anabolic) will help to suppress the immune system so that the muscle can recover; I’ve added a link below on the difference between corticosteroids and anabolic steroids below. If the cause is masticatory muscle myositis then corticosteroids would be the treatment of choice. Regards Dr Callum Turner DVM

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Jack Russell Terrier
Serious condition
1 found helpful
Serious condition

Has Symptoms

locked jaw
Sunken eyes

My sweet Lily girl was diagnosed with Masticatory Myositis. I noticed that she couldn't open her mouth after being away for a week. I was recently in a car accident and was recovering with my Father looked after Lily. He stated she was " a messy eater" turns out she was trying to suck the food through her teeth. I immediately took her to the emergency vet clinic where she was diagnosed. My cousin who is a veterinarian said she has only seen one other case since she has been practicing veterinarian medicine. She gave her a steroid shot and wrote her a prescription for Prednisone. She said to let lily rest and see if the steroid shot helped her regain some jaw function however I haven't seen any so far. I ran some wet dog food through the food processor and she was able to get it down after 45 minutes. I'm not sure how I can administer her medicine if she cannot open her mouth. Is her stage to far for comng back. I'm very heartbroken and need advice on what to do. She is an older dog and I do not want to euthanize her but I don't want to see her in pain either.

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
2129 Recommendations

Masticatory myositis when treated promptly has a good prognosis, the problem is when the condition becomes chronic scarring can occur in the muscle leaving treatment ineffective and the prognosis poor. It would be worth giving Lily sometime to respond to treatment as it may have been going on for a while; a muscle biopsy of the masseter muscle will show the level of scar tissue and can give a good indication of a prognosis. Treatment with prednisone is usually for a few weeks, but in severe cases six months or more of treatment may be required. Regards Dr Callum Turner DVM

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Mini dachshund
Serious condition
0 found helpful
Serious condition

Has Symptoms

Throwing up
Jaw pain

Medication Used

Cerenia injectable

Our dog was just diagnosed with Masticatory Muscle Myosistis. He is a 12 lb. Miniature dachshund. He started taking 100mg of Prednisone twice a day yesterday. When will we see any return of jaw funcation?

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
2129 Recommendations

Response to treatment of masticatory myositis varies between patients and severity; it may take two to four weeks to regain function again. Although function may return, long term treatment may be required; treatment may consist of three weeks of high dose prednisone with a review after three weeks and if successful, the prednisone is tapered off over the course of a few weeks. Regards Dr Callum Turner DVM

My 8 1/2 yo English Mastiff was recently diagnosed. His skull has loss muscle and his eyes are suken but his jaw is fine. I am scared to death!! Any advise for us? 😢

My dog has an MMM breakout every 3-4 months. I hate those high prednisone doses, and wonder if keeping her on a daily low dose could prevent the need for the weeks long high dose treatments? Any help appreciated. I'm going to get her to the vet this time and ask this of him also.

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