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My dog yelps and can't open his mouth. Is his jaw locked or sore?

Updated on September 23rd, 2025

Pet's info: Dog | American Staffordshire Terrier | Male | neutered | 1 year and 7 months old | 36 lbs

My dog can’t open his mouth fully and yelps while doing it, I gave him a bone to see his reaction and it’s like the jaw had locked and he was struggling to get the bone out whilst yelping, do that didn’t go to how I planned, he won’t let me open his mouth and his trying to hi five me to tell me it’s sore every time I go to touch his mouth. he ate sardines & biscuits earlier this morning with no trouble, but big things his struggling to open the mouth fully with.

1 Answer

Most Helpful Answer

Juliana,  DVM

Answered By Juliana, DVM

Veterinarian

Published on March 8th, 2018

I’m sorry Oscar is dealing with this. He is quite a handsome guy! Pain opening the mouth can be caused by a few thing including infections or an autoimmune disease called masticatory muscle myositis (MMM). I would have Oscar evaluated by his veterinarian. They may be able to get an idea based on their exam, and they can also do special blood testing for MMM. They can start Oscar on medication as indicated to help him be much more comfortable. In the meantime continue feeding him very soft foods. Hope he is feeling much better soon!
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