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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.

Masticatory Muscle Myositis Average Cost

From 415 quotes ranging from $1,000 - $3,000

Average Cost

$1,500

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
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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.

Cancer

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.

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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.

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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.

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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.

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Masticatory Muscle Myositis Average Cost

From 415 quotes ranging from $1,000 - $3,000

Average Cost

$1,500

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Masticatory Muscle Myositis Questions and Advice from Veterinary Professionals

Need pet health advice? Ask a vet

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Ask a Vet

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Ruby

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Italian Greyhound

dog-age-icon

5 Years

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Serious severity

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2 found helpful

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Serious severity

Has Symptoms

Muscle Atrophy

Our dog Ruby was diagnosed with MMM about a year ago. She didn't have the usual symptoms other than muscle wasting. She never had swelling or difficulty opening her mouth. She has been on several medications and has seen multiple doctors but they can't get the muscle wasting under control. She was first put on 5mg Prednisone and Cyclosporine. The vet is now weening her off both those meds and she has been taking 60mg Mycophenolate twice daily. We don't know what to do. Her poor face keeps sinking in more and more. We feel that she will eventually get to the point that she has no jaw muscle and will not be able to eat. We live in Southern California and will do anything to help her. If anyone has any suggestions or knows of a vet that specializes in this disease, please let me know. We are feeling desperate.

Aug. 26, 2018

Ruby's Owner

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Dr. Michele K. DVM

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1611 Recommendations

I am sorry that is happening to Ruby! It might be a good idea to have an internal medicine specialist see her, if your veterinarians have not been able to control her disease. They may be able to provide alternative care for her, since it is obvious that you love her and want to help her.

Aug. 26, 2018

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Pooh

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pit mix

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3 Years

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Moderate severity

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4 found helpful

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Moderate severity

Has Symptoms

Swelling

My girl Pooh is on her 3rd or 4th bout with MMM. She's 65lbs has been on 10mg of Prednisone for about a year and a half, and she started an episode of swelling a couple of days ago. Yesterday the vet had me give her 30mg (once per 24hrs) of Pre., 50mg of Benadryl and a Prilosec to protect her stomach. Her swelling did decrease a bit by 6:30 pm but was back by 4:30 am. I really want to know if I can fight this more aggressively? She is still eating, drinking and will chew a bully stick. I have pictures I can email. She looks like she's been hit by a bat.

Aug. 24, 2018

Pooh's Owner


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Dr. Michele K. DVM

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1611 Recommendations

Some cases of MMM need to be treated very aggressively, and dosages of Prednisone of up to 2 mg/kg twice daily have been used. That would make her twice daily dosage 60 mg. Since I can't see her, it would be best to call your veterinarian and ask if this is something that would be appropriate, as those dosages of steroids can have side effects.

Aug. 24, 2018

Thank you!

Aug. 24, 2018

Pooh's Owner

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Pampos

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Labrador Retriever

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18 Months

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Fair severity

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0 found helpful

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Fair severity

Has Symptoms

Sunken Head
Spill Water

I recently got my lab to the vet for his routine parasite pill and when he saw him he told me he has atrophy to the tempral muscle. No further examination more than seeing the dog's head. Indeed his head is sunken in both sides. When I asked him what to do he told me nothing than keeping an eye on him for other symptoms. He can open his mouth properly and eat as well. No loss of appetite or joy. He spills water when he drinks but I think he does this since he was a puppy. I am quite concerned if this is just a sign of something upcoming (like MMM) and what should I do further on to prevent it.

Aug. 17, 2018

Pampos' Owner

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3320 Recommendations

There are different causes for muscle atrophy which may include conditions like masticatory muscle myositis, neurological conditions, nutritional disorders, hormonal conditions among others; if there are no other symptoms we cannot say for certain what the cause is so there is no real treatment or management options, monitor for other symptoms and follow up with your Veterinarian. Regards Dr Callum Turner DVM

Aug. 17, 2018

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Dino

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German Shorthaired Pointer

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Nine Years

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Serious severity

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0 found helpful

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Serious severity

Has Symptoms

Hard To Swallow Or Open Jaw.
Head Sunken

My dog was diagnosed with MMM on Thurs. I gave him his first steroid Thurs pm. He had a meds Fri-Sun and we see no change yet. How soon would we see improvement if meds were to help? He has displayed symptoms we thought we just older age setting in and very high heat index for about 3 weeks prior to diagnosis. Is that considered early onset? Or too far gone for treatment?

July 2, 2018

Dino's Owner

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recommendation-ribbon

3320 Recommendations

Typically we expect to see improvement within seven to ten days, but treatment may be required for a few weeks depending on the case; this isn’t a quick fix unfortunately. If your not seeing any improvement by the weekend you should visit your Veterinarian. Regards Dr Callum Turner DVM

July 3, 2018

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Lucy

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Wolfdog

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18 Years

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Serious severity

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2 found helpful

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Serious severity

Has Symptoms

my 18 year old wolf/chow/shepherd lost a lot of weight, half her head is sunken in on the left side, the masticatory muscle is gone and her jawbone sticks out. her eyes sunken in and her eye lashes look like they withered away. she has a stiff gait and just feels lousy. she keeps pawing her snout and shaking her head as if her ears are bothering her. i clean them out often, so maybe her brain is affected? i took her to the vet and the vet examined her and said she doesnt think anything is wrong with her. i dont believe the vet. the vet looks too young to be experienced enough. She gave me inflammatory pills, but i think shes trying to treat the symptoms she said she looks normal. i been with my girl 18 years. i know what is normal. i upped her diet which is raw to include pasta for weight gain and greens for plant enzymes. we still go for walks and i give her reiki treatments every day. Any help on what else i may do would be greatly appreciated, Thank you Will Wood from Port Angeles

June 10, 2018

Lucy's Owner


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Dr. Michele K. DVM

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1611 Recommendations

Will, I am sorry that Lucy is having these problems. If you do not feel that your veterinarian was aware of your concerns and the changes that she is having, it may be a good idea to seek a second opinion. Without seeing her, I can't comment on any treatments that may help, as I don't know what is wrong with her. If you are sure that something is going on and she needs further care, a second opinion is never a bad idea.

June 10, 2018

How is your frenchie? Our french bull dog started having issues opening his mouth this weekend and we took him to the vet this morning. Negative results on the XRay so she came back with an MMM diagnosis. She's sending us home with his first round of steroids and I am not sure what to expect. Will he be able to go back to his normal playful self? Or is this something that is going to change him for the rest of his life?

July 24, 2018

Ainslee C.


My 7 year old French Bulldog is currently going through his second bout of MMM in 4 years. He is on the standard course of steroids but this time, the disease was much more aggressive and he now has muscle wasting on the right side of his face. What makes it more stressful is that Myositis is not common and many Vet's have not experienced this so it's hard to get it right.

June 18, 2018

Sandra R.

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apollo

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French Bulldog

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2 Years

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Moderate severity

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0 found helpful

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Moderate severity

Has Symptoms

Pain Hurting

My 2 year old french bulldog was dx with mmm. My problem is getting him to take his medication because he hurts so bad. Any suggestions? He took the first 3 doses and now wont open his mouth to take any more.

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Gunther

dog-breed-icon

Mixed

dog-age-icon

11 Years

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Serious severity

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0 found helpful

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Serious severity

Has Symptoms

Labored Breathing

Our dog, Gunther (an 11 year old shepherd mix), was diagnosed with MMM two years ago, his symptoms were having trouble opening his mouth. He was treated with corticosteroids for a few weeks and has been in remission since two weeks ago. Two weeks ago, he presented with labored breathing and drooling. The vet mis-diagnosed it initially saying it was allergies but later that same week he started having trouble opening his mouth again and the vet started him back on the steroids saying it was now a flare-up of his MMM. He's been on the steroids for a few days now but still has no energy and still is breathing very heavily. Will this labored breathing clear up in a week or so of being on the steroids? Since this was not one of his symptoms with his initial diagnosis, I'm concerned regarding his labored breathing. Will this clear up after being on the steroids for a week or two?

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Priscilla

dog-breed-icon

Dachshund

dog-age-icon

5 Years

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

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0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

Has Symptoms

Difficulty Swallowing

My long hair mini dachshund Priscilla was diagnosed with mmm in early December of 2018. She weighs 11 pounds. She was started on 10mg per day of predisone. She was never in any pain,but she cant open her mouth very wide and she has difficulty swallowing food and water. She has to swallow several times to get it down and usually spits a little of her water up. I have her on soft food and i feed her so she doesnt gobble and get choked so her weight is stable, but I just havent seen a big improvement at all. For about 1 month she has been on 15mg per day of predisone and the vet said we need to decrease it now. Im just wondering if 15mg a day is enough to see results. I know she is small, but i just want to be sure that Ive gotten her as well as possible before i reduce the predisone. Thank you so much for any advise!

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Bill

dog-breed-icon

Mini Sharpei

dog-age-icon

2 Years

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Serious severity

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0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Serious severity

Has Symptoms

Locked Jaw, Stiff Gait, Falling Food

My dog, a mini Sharpei, was recently diagnosed with MMM. He has "always" had stiff legs, his mouth has "always" been messy. He "always" seemed to have a dislike of sitting with his bottom fully on the floor. About 2 weeks ago my daughter noticed that he only sat of stood. He whimpered when she tried to physically help him into the sitting position. 5 days ago we noticed he was dropping food from his mouth and was "more messy than ever". 3 days ago his weight loss was noticeable. We noticed he was not getting food or drink in his mouth because it was/is locked tight. He was very motivated to eat/drink has a fleshy mouth, and buried his head in his dishes that when we heard his tongue working hard, we assumed he was getting food. No. At the end of October he weighed 38.7 pounds. Yesterday a.m. he weighed 31.4. The vet gave him 1 liter of water under the skin and a prednisone shot. We picked him up and tried to feed him cat food through the side of his mouth. We had an xray done as well. It found that he was missing "several" teeth (mandibular/maxillary). He also has tiny ears with chronic yeas issues (bilateral otitis externa/external ear canal stenosis). Also, he had eye surgery, but continued/s to shut his eyes for long periods and drops tears constantly. I thought these were all separate issues. Are they? Our handsome Bill was hospitalized this a.m. so he could receive shots daily and not pills, be syringe fed (shouldn't he be intravenously fed), and monitored. He has made no progress. Is this effort dire? Should we give up? The vet could not open his jaw while he was sedated. I should add that his "blood work" looked "pretty good" with none of the counts "too elevated"

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Annie

dog-breed-icon

Cavalier King Charles Spaniel

dog-age-icon

21 Months

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

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0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

Has Symptoms

Our King Charles cavalier Cocker mix was diagnosed with MMM as a puppy. She has been on high and maintenance doses of prednisone numberous times. She was doing well on 5mg per day. Her recent reduction per our vets instruction 5 mg every other day. It's been two weeks and she is showing signs of a problem. She can not open her mouth enough to catch her mini tennis ball which she normally does with precision. Should she go back on a high dose to force it into remission or back on 5mg per day. Her dose has been gradually reduced from a high dose to lower dose 5 times now and it has always come back.

Masticatory Muscle Myositis Average Cost

From 415 quotes ranging from $1,000 - $3,000

Average Cost

$1,500