A dog can have many different expressions throughout the day and night. He may also do some odd behaviors and have different, atypical expressions. A dog may keep his mouth open for a variety of reasons. If he is keeping his mouth open and he doesn’t normally do that particular behavior or expression, then you may notice it immediately. 

You may also notice if he is panting when his mouth is open, or looks as if he is having trouble breathing or is congested. If your dog is keeping his mouth open, and is not willing to close it, then you should contact your veterinarian. Causes can include:

If your dog is keeping his mouth open, he may be experiencing a symptom of an underlying disorder. Reasons your dog may be doing this for a prolonged period include:

Your dog may simply be trying to cool down his body by panting with his mouth open. The air circulates through your dog’s body and helps him when he is too warm.

Also referred to as mandibular paralysis, trigeminal neuritis is paralysis of a dog’s muscles used for chewing. When inflammation in the trigeminal nerves occurs, your dog may keep his mouth open and not have the ability to chew.

If your dog has an abscessed tooth, or any tooth pain, he may want to avoid closing his mouth. He may keep his mouth slightly open in order to avoid touching the tooth with the teeth above or below it.

If your dog suffers from allergies or has a cold, he may have congestion in his nasal passages. Like humans, it may be difficult to breathe through the nose when conditions like this occur, so he may keep his mouth open to ease any breathing difficulties.

If you notice your dog keeping his mouth open for a prolonged period of time and he cannot eat or drink in a normal way, you should contact your veterinarian. Once you arrive at the veterinarian’s office, he will immediately begin to assess his symptoms. He will need more information from you regarding your dog’s behavior. He may want to know how long your dog has been having the symptoms of his mouth being open and if he is having any pain and discomfort, or other symptoms such as drooling or panting.

Your medical professional may perform a complete physical examination, along with a urinalysis, biochemistry profile, and blood work. He may also choose to conduct imaging of your dog’s jaws and mouth to check for any trauma or tooth abscess. If he suspects a neurological condition, he may perform a neurological examination to check for any nerve abnormalities, such as trigeminal neuritis. 

Once your dog is diagnosed with a condition, your veterinarian will give you treatment options in order to help him recover. Treatment depends on the condition your dog has been diagnosed with.

It will be difficult to prevent your dog from having certain underlying health issues that would cause him to keep his mouth open. However, there may be things you can do to possibly minimize the chances. Being proactive in your dog’s overall health is key to ensuring he is less prone to developing conditions such as tooth abscess or nasal congestion. When you take your dog to the veterinarian for his routine visits, the medical professional will check his teeth and gums each time. This can help prevent a painful tooth abscess from forming. Also, if your dog has allergies and gets nasal congestion from time to time, knowing which medication to give him (prescribed by your veterinarian, of course) will minimize the need to have his mouth open in order to breathe.

The cost of allergy care for your dog may be approximately $350. The cost of a tooth abscess treatment will be about $1200.