Dog Cant Open Mouth Wide – What is the Reason?

If your dog cant open mouth wide, there is an underlying issue to be addressed. We have written an extensive guide on what all problems could be causing this issue. Do read and learn more about what you need to do.

There can be several reasons why your dog can’t open its mouth wide. From joint problems to muscular conditions, your dog might be going through a lot of pain in its jaw, and thus, it is important to get the quick and correct diagnosis and treatment to live an active and happy life again. 

In this article, we list all the common reasons and possible problems that might be causing your dog not to open its mouth wide. Do read them till the end because you never know what might strike you to pay a visit to the veterinarian and get your dog the help it deserves. 

Dog Cant Open Mouth Wide

Why Can’t My Dog Can’t Open Its Mouth Wide?

Dogs are jolly animals and do not mind a little pain. Thus, if your dog is crying in pain when trying to open its jaw, it means something serious is going on in and around its mouth. 

If your dog has jaw pain, it will cry or jerk its head back, especially when chewing or eating something. Also, the food might drop off of his mouth because he is only opening a fraction of his mouth. 

Watching your dog suffer from this problem can be difficult, and thus, it is important to reach t to the root of this problem. Here are some of the common reasons this might be happening.

You might like to read: Why Does My Dog Put My Arm In His Mouth? 

Bone and joint problems  

There are several problems related to the bone and joint of dogs that can make it difficult for them to open their mouth (the term for this condition is trismus). Some of the conditions related to this problem include 

  • Jaw Dislocation, which can lead to arthritis, and if the situation worsens, your dog’s mouth will fail to open at all. 
  • Craniomandibular osteopathy: where abnormal bone growth leads to much pain in the jaw and head area of dogs, sometimes to the point where the only option left is euthanasia. 
Dog Cant Open Mouth Wide

Craniomandibular osteopathy is a non-cancerous and non-inflammatory condition in young and growing dogs of around 3 to 8 months. It can occur in all breeds but is hereditary in West Highland White Terriers and Scottish Carin.

It can also give rise to tumors, infection, inflammation, or fracture to the bones, cartilage, bone capsules, joints, and other areas of the dog’s jaw. It is highly uncomfortable for the dogs to deal with this pain and thus, takes away their zest and active approach towards life. 

You might like to read: Why Does My Dog Whine After Eating?

Muscular problems

Masticatory Myositis

One of the most common muscular problems dogs deal with in their jaw area is masticatory myositis. This inflammatory problem invites the immune system to attack the chew food muscles. 

The 2M fibers of these muscles are not found anywhere else in the body and are often found swollen when the dog fails to open its mouth completely. With time, the disease causes excruciating pain in the jaw area of the dog in case it tries to open its mouth and thus, should be medicated as soon as possible.

If treated early and well, your dog might be able to go back to its normal life. However, if the disease remains untreated, the damage can be permanent, and your dog shall have to remain on medication for the rest of its life. 

Dog Cant Open Mouth Wide

Muscular dystrophy 

Muscular dystrophy is a term used to refer to collective genetic diseases that affect muscular, digestive, cardiac, and other body systems. Any breed can be affected by this problem, but the young pups usually catch this condition. 

Male dogs are more prone to exhibit the symptoms, and females can be silent carriers. There is no cure for this problem currently, and thus, it may eventually lead to the dog’s passing. 


Polymyositis is a condition that attacks the body’s skeletal muscle, which includes those that help in chewing food. In this condition, the immune system also attacks the muscles, but the infection is caused by different organisms, including viruses, bacteria, protozoa, and more. 

In addition to trismus, dogs exhibit several other symptoms, including lethargy, weakness, difficulty walking and moving their neck muscles, etc. It can also cause swelling and pain in the muscles and thus, making it difficult for the dog to open its mouth. 

Blood tests, MRI, and muscle biopsy are some of the tests required to diagnose the problem and whether the treatment will come to fruition depends on how your dog’s body responds to it. 

Tumors and trauma to the muscles are also common reasons why your dog cannot open its mouth and, thus, should be looked into as well. 

You might like to read: How To Get Dog Hair Out Of Throat?

Dog Cant Open Mouth Wide

My Dog Cries When Opening Mouth Wide?

Your Dog cries when opening its mouth wide is because it is in pain or extreme discomfort due to some underlying issue. While we have discussed a few of the conditions that it may be suffering from, in the above sections, there is more that we want to discuss in this.

Other problems can lead to trismus, including

  • Foreign objects, including a piece of wood or bone, wedged in the back of the mouth causes physical pain. 
  • Dental problems or diseases can be quite troubling to the teeth and gums of dogs.
  • Tetanus infection, which is rare in dogs but if it occurs, can cause lockjaw. 

And leave the mouth stiff and in pain. When your puppy is suffering from this infection, they need strong care and support and are treated with antibiotics, along with therapy. 

The ‘lock jaw’ part of the tetanus infection brings us to the very important condition that affects dogs of all breeds and ages as well – it is called Lock Jaw and is concerned with temporomandibular joint or TMJ, which is a joint where the jaw meets the skull. 

The problems in this joint can occur due to chronic inflammation, fractures, luxation, or other developmental factors. There is also a possibility of a tumor growing in the joint and thus, causing trouble for your dog in opening its mouth.

Some of the symptoms that direct that your dog might be suffering from lockjaw include swollen jaw, pain, fever, weight loss, dehydration, paralysis of the face, abnormal facial expression, loss of appetite, jawbone shift, masticatory muscle atrophy, inability to open or close jaw, salivation, etc. 

If any of the symptoms show up, immediately seek medical assistance, and after the physical examination, diagnostic tools like blood tests, CT scan, MRI, etc., come into the picture. The success rate of the lockjaw is quite variable. However, the treatment is available in most dental care clinics, and thus, you can hope for the best for your furry friend. 

You might like to read: Why Does My Dog Have A Pink Spot On His Lip?

Why do dogs breathe with their mouth open? 

There can be several reasons why a dog is a mouth-breather—also, open mouth functions to help dog breathing, cooling, and communication. If your dog is overheated, it cools itself down by breathing. 

Your dog needs to cool down

Dogs do not sweat via their skin, as is the case with humans. Thus, they need another way to feel cool in their body, and so, they leave their mouth open to cool down.

When it comes to communication with an open mouth, it lets its owner know if it is afraid or in pain. However, if the mouth is softly open and resembles a smile, it means that your dog is calm and cool. 

They also leave their mouth open when they are extremely happy or excited about the place they are in or the food they are about to devour, or anything else. 

Dog Cant Open Mouth Wide

It could be a sign of a condition

However, this must not be confused with the fact that dogs are completely capable of breathing through their nose. Both ways are completely normal ways of breathing. However, certain conditions can cause breathing problems in your four-legged friend, and these difficulties would include:

  • Labored breathing or dyspnoea – If you notice your furry friend is struggling to inhale a sufficient amount of oxygen, especially if it hasn’t exercised or run enough, then you must get it tested by a vet. 
  • Fast breathing or tachypnoea – If your puppy is breathing faster than usual or has shallow breathing for an extended amount of time, you must also get it tested by a vet. 
  • Panting – All dogs pant after a good session of exercise or running. However, if your dog is panting even when doing nothing, it indicates a breathing problem and should be examined by a vet. 

You might like to read: Can A Dog Die From Swallowing A Scrunchie

A Few Final Words

As we have read already, there are several reasons behind your dog’s inability to open its mouth/jaw wide or without pain or stiffness. We have tried mentioning most of them in this article. 

Still, it is on you to take care of your furry friend by getting it to the vet, who diagnoses its problem correctly and provides the treatment that helps it recover from the problem and live a normal and healthy life. 

Dog Cant Open Mouth Wide

We thank you for reading the article and hope that we have answered all your questions. If we left something out, do let us know in the comments below and we will add it to the article.

We have also written about other conditions in dogs such as Dog Cant Lift Head and Dog Teeth Bleeding When Chewing Bone. Do read these because odd behaviors can often mean that your dog is suffering from a problem.