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Why are my dog's cheeks sunken but he still has a good appetite?

Updated On September 23rd, 2025

Pet's info: Dog | Jack Russell Terrier | Male | neutered | 9 years and 3 months old

My dog, Mopar, in the last couple days, has had his cheeks/jaw become noticably sunken in. His cheek bone is protruding, and his temple also feels slightly indented. Despite this, he has a very good appetite. He's 9 years old, and a very active dog. My trusted vet opens Monday, but there is another that opens for just an hour tomorrow. What do you think is causing this? Should I rush him to the vet as soon as possible, or would it not hurt to wait a day?

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1 Answer

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Answered By Dr. Melanie, BVSc MS

Veterinarian

Published on November 7th, 2020

I'm wondering if Mopar is suffering from masticatory muscle myositis. This is an immune system disorder in which the dog's immune system identifies the dog's own muscle tissue as foreign and attacks it. This causes the sunken in appearance on the face. Because he has a good appetite, I think it's fine to wait until Monday to have him seen but do not wait any longer than that. I hope this helps!

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