Masticatory Myositis in Dogs: Ginger’s Painful Mouth

Masticatory myositis is an auto-immune disease. In other words, the immune system attacks the dog’s own jaw muscles as a foreign invader.

As a result, the puppies are in severe pain and unable to open their mouth. Can you imagine if it hurt when you tried to eat? And I mean really hurt.

Some breeds, including Cavalier King Charles Spaniel, carry a genetic predisposition to this condition. However, auto-immune diseases require two things:

  • a genetic predisposition
  • and a trigger

The trigger, though, can be many things, including:

  • infections bacterial or viral
  • vaccinations
  • environmental toxins
  • allergens
  • adverse reactions to medication
  • even stress
Masticatory Myositis in Dogs: Ginger's Painful Mouth
Cavalier King Charles Spaniels are one of the breeds predisposed to masticatory myositis
Other predisposed breeds:
  • German Shepherds
  • Labrador Retrievers
  • Golder Retrievers
  • Doberman Pinschers

Source: VCA Hospitals

Ginger’s story

You know how adorable Cavalier King Charles Spaniel puppies are. Ginger was no exception. Ginger was a happy girl. She played and enjoyed being loved with all her might.

Feeding was one of the highlights of her day.

It took all but twelve hours for all that to change.

Ginger’s symptoms

Ginger’s turn from a normal puppy to a dull, quiet and withdrawn happened fast. She didn’t want to eat and when anybody tried to touch her head she’d back away and yelp. Something was obviously wrong.

Veterinary exam

Quickly, Ginger’s parents took her to a veterinarian.

The most likely causes behind mouth pain in dogs are dental issues or foreign bodies. Ginger was only three months old. Could she have something stuck in her mouth? Could it be a stick injury?

Unfortunately, Ginger would let the veterinarian get anywhere close to her head at all. The only way to examine her mouth was giving her general anesthetic.

Diagnosing Ginger

To the veterinarian’s surprise, he was unable to open Ginger’s mouth even under anesthesia. What gives?

Follow-up x-rays didn’t offer any answers. Everything looked normal.

Symptoms of masticatory myositis in dogs include:

  • inability to open mouth
  • inability to eat
  • swollen masticatory muscles
  • severe facial pain

However, the only way to definitely diagnose masticatory myositis in dogs has been a biopsy. Fortunately, there is now a blood test that can measure the antibodies attacking the muscles too.

Diagnosing conditions so rare that you hardly hear about them is always a challenge.

Pain relief

The first thing Ginger’s veterinarian did was to take care of her terrible pain. Ginger’s parents brought her home with strong pain medications. Likewise, they also received recommendations for soft moist food. Finally, the poor girl could get some nourishment into her.

The pain meds did make Ginger feel much better and she started eating.


Unfortunately, all the medication upset her digestive system. The only option was to stop all medication. That, however, brought the pain back.

It became a matter of finding a middle ground between

  • controlling Ginger’s pain
  • while minimizing the risk of damaging her GI system

In the meantime, her veterinarian kept working on the diagnosis. All this happened before the blood test to diagnosis masticatory myositis in dogs became available.

Blood tests, just as the x-rays, didn’t show anything useful. Everything looked normal.

Thinking out of the box

Could something such as electromyography (EMG) provide needed answers? It would be a non-invasive way of figuring out what was going on with Ginger’s chewing muscles. It is not a veterinary test but maybe they could pull it off.

Then, Ginger’s veterinarian found a freshly-published report about masticatory myositis in Cavalier King Charles Spaniels. Finally, there was the answer to Ginger’s severe jaw pain. Her veterinarian worked with San Diego laboratory to confirm Ginger’s diagnosis.

Treating Ginger

As soon as Ginger received treatment with immunosuppressive medications, she felt immediately better.

As a fallout of her illness, Ginger still has some residual problems. But she is feeling good and continue to enjoy her life.

Ginger’s story took place in 2013. Today, diagnosing her would have been easier. Treatment options, however, haven’t changed much.

I decided to feature this older story to highlight the dedication and persistence of her veterinarian. He didn’t stop until he got to the bottom of it. Which is what makes a good veterinarian. No, that is what makes a great veterinarian.

Source story:
Ginger, a three-month-old Cavalier King Charles Spaniel puppy who had a very painful mouth

Further reading:
Masticatory Myositis in Dogs – When Chewing Hurts!

Categories: Autoimmune diseaseDog health advocacyMasticatory myositisReal-life Stories

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Jana Rade

I am a graphic designer, dog health advocate, writer, and author. Jasmine, the Rottweiler of my life, was the largest female from her litter. We thought we were getting a healthy dog. Getting a puppy from a backyard breeder was our first mistake. Countless veterinary visits without a diagnosis or useful treatment later, I realized that I had to take Jasmine's health care in my own hands. I learned the hard way that merely seeing a vet is not always enough. There is more to finding a good vet than finding the closest clinic down the street. And, sadly, there is more to advocating for your dog's health than visiting a veterinarian. It should be enough, but it often is not. With Jasmine, it took five years to get a diagnosis. Unfortunately, other problems had snowballed for that in the meantime. Jasmine's health challenges became a crash course in understanding dog health issues and how to go about getting a proper diagnosis and treatment. I had to learn, and I had to learn fast. Helping others through my challenges and experience has become my mission and Jasmine's legacy. I now try to help people how to recognize and understand signs of illness in their dogs, how to work with their veterinarian, and when to seek a second opinion. My goal is to save others the steep curve of having to learn things the hard way as I did. That is the mission behind my blog and behind my writing. That is why I wrote Symptoms to Watch for in Your Dog, which has turned out being an award-winning guide to dog owners. What I'm trying to share encompasses 20 years of experience.

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