A dog's jaw can chatter when it is feeling stressed or anxious, but it can also be symptomatic of a seizure or an ongoing epileptic condition, according to PetMD. If a dog's jaw is chattering on a regular basis and the dog is exhibiting other symptoms, such as appearing dazed, falling on its side, salivating often, vocalizing or trying to paddle with its legs then the dog should be brought into a veterinary clinic immediately, states PetMD.
Seizures and epileptic conditions are serious and can be life threatening if not controlled with medication. There are also home adjustments that can be made so that the dog is less likely to have these fits. The only way to diagnose and then treat the dog properly is through veterinary care, reports WebMD.