What might cause a dog's jaw to become painful and lock?

There are many reasons why your dog's jaws may be locked open or closed. He might have fractured or dislocated his jaw, for example. Or developed a large and painful abscess in his mouth, or behind his eye. He might be suffering from osteoarthritis. He might have contracted the bacterial disease tetanus, commonly known as lockjaw - although it's fairly rare in dogs. Given the range of possible causes, your pal needs to be treated by a veterinarian.

One thing is certain. If your dog cannot eat or drink properly, he's obviously feeling the pain - physically, psychologically, or both. And without your help, his health will be in jeopardy. Whatever the problem, a dog that's struggling to open or close his mouth is not going to recover on his own.

– Dr. Larry McDaniel, DVM for the “Purina® Animal Instincts” Podcast Series

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