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An aging dog displays all kinds of worrying symptoms. One of the major ones is the changes in the skin—specifically the appearance of bumps and lumps.
Such canines feature uneven skin here and there. However, when the skull caves in especially above the eye, you should be perturbed.
The natural aging process doesn’t cause severe hollowing in canines. If your dog is displaying these symptoms, it’s time to take action.
Healthy dogs have strong muscles that support all body parts. Even with age-related bumps and lumps, the muscles should keep the canine system working well.
In particular, the skull should remain in top shape as it contains the central nervous system.
So why is your dog’s head caved in?
Well, it can be caused by two things:
1. Atrophy of muscles
Most cases of sunken skulls in dogs are a result of what’s referred to as dog skull muscle atrophy.
In simple terms, atrophy is the decreased size in a body part, tissue, organ, or cell.
To say that something is atrophied means that it used to be of normal size but has since shrunk. It may be that the number of cells of the body parts has gone down.
Canine muscle atrophy is the loss or wasting away of muscles in the muscle tissue. Most cases occur in the hind legs but they can present in other areas as well.
The phenomenon is caused by surgery and injury. It can also happen slowly over a long period without any symptoms whatsoever.
Muscle atrophy can happen to any breed but large dogs such as German shepherds and sighthounds including Greyhounds are more prone to the illness.
Masticatory Muscle Myositis
Muscle atrophy is caused by several things, one of which is myositis or inflammation of certain muscle groups.
For a dog that has a sunken head, the probable inflammation occurs in the masticatory muscles (muscles responsible for chewing). These include cheek, pterygoid, and top of the head muscles.
The reason is that they contain a unique fiber that is absent in other skeletal muscles and may suffer ill effects because of it.
Masticatory muscle myositis (MMM) is essentially a disorder that causes the dog’s immune system to attack its own muscles thinking they are foreign.
The attack causes the muscles to be inflamed resulting in pain for your furbaby.
Besides making it difficult for him to chew food, MMM may cause the head muscles to be atrophied. This is where the area above the eyes appears sunken.
What Does It Look Like?
Skull muscle atrophy changes the appearance of a dog’s face in many ways.
For one, it makes the upper eyelid droop on the affected side (ptosis).
The pupil of the affected eye may also look constricted (miosis) while the entire eye will appear sunken.
That’s not all – the eyelid of the affected eye is usually raised and red in color.
Well, if you are not keen, you may not pinpoint all these. Plus, not all dogs suffer all the symptoms.
The glaring symptom, in most cases, is the appearance of a sunken skull right above the eye.
In the initial stages, MMM causes swelling of the head muscles – especially at the top of the head.
A few weeks later, muscle wasting around the face will be evident.
Before the skull is atrophied, the dog’s eyeball may protrude and the eye may swell. In some cases, the eyeball will deviate causing vision problems.
Other symptoms that signify MMM include food and water regurgitation, breathing problems (rarely), and difficulty swallowing food.
Some breeds such as Shetland sheepdogs, Rough coated collies, and Australian cattle dogs) are at a higher risk of developing skin lesions and suffer great pain and discomfort as a result.
Causes of Masticatory Muscle Myositis
What triggers MMM is not yet clear. However, experts believe that it is a disorder related to the immune system of the dog.
It causes the system to create antibodies to attack muscle fibers thus destroying them and triggering inflammation and death of cells.
Other causes of MMM may include the following:
- Polymyositis: this is a muscle disease that causes problems in muscles across the dog’s entire body. It is also an immune-mediated process that causes weakness, reluctance to exercise, and sometimes lameness.
- Inflammatory cancerous illnesses of the teeth, mouth, skull, and eyes. These encompass fractures, oral ulcers, tooth root abscesses, tumors occurring behind the eye, oral tumors, stomatitis, and joint dislocations.
- Loss of input from the trigeminal nerve: The trigeminal nerve is responsible for supplying nerve branches to the masticatory muscles. When the nerve loses function (trigeminal neuropathy), muscle atrophy may occur. Signs and symptoms of trigeminal neuropathy include an inability to close the mouth and a dropped jaw.
Treatment of Masticatory Muscle Myositis
The most effective solution for canine myositis is to counteract the immune’s system excitement for producing antibodies to attack masticatory and head muscles.
To do this, the vet will recommend high doses of immunosuppressive drugs. The simple term of these drugs is steroids. Other immunosuppressive medications can be used as well.
After countering myositis, the dose of steroids will be reduced and if no relapse is present, they will be completely eliminated.
Oftentimes, a low dose of the drugs is needed to keep atrophy at bay.
Dogs with MMM may have a few attacks over the first few weeks of treatment but these will subside.
To keep symptoms from coming back, your dog may be put on corticosteroids.
Some canines will need to undergo prednisone therapy for as long as they live but others can do without it.
During the initial phase of myositis, pain medications may be necessary to keep the pet comfortable.
Sadly, most pups change their feeding habits even after treating the disorder. You may want to soften kibble with some water to motivate your dog to eat.
Sometimes, feeding your dog with canned food works best.
Related Post: How Much Canned Food Should You Feed a Dog Per Day?
Will Your Dog Recover Completely?
The response to MMM treatment depends on a number of factors. These include the extent of the disease, treatment offered, and the dog’s response to treatment.
For instance, if the degree of inflammation is high, the dog’s outlook may not be so great.
Also, if treatment is started late, the muscle function may not return normally.
Luckily, if the muscle wastage is not severe and if it is caught early, your pet will get better. This is also true if the underlying cause of the disease is successfully treated.
2. Nerve Issues
Nerve problems can also cause caving in of a dog’s head. The cases are rare but they do happen.
If there’s any problem with the nerve supplying the facial muscles, it may trigger muscle atrophy.
You can tell that there’s a nerve issue if you spot a sunken skull on only one side of the face.
Nerve problems can only be handled by experts. Treatment options such as acupuncture, laser therapy, and anti-inflammatory meds may also work. Other instances require a surgical intervention.
When you are used to your dog’s facial structures, you can easily tell when something is amiss.
If you find yourself asking the question, “why is my dog’s head sunken in behind eye?” this guide has hopefully shed some light.
The answer lies in either masticatory muscle myositis or nerve damage.
For a proper diagnosis and treatment, take a trip to the vet together with your dog.
Image sources: 1, 2, 3, 4
Dr. Rochelle Batanan (DVM) is a veterinarian based in Singapore with a wealth of experience in veterinary medicine. She obtained her Doctor of Veterinary Medicine degree from the University of Southern Mindano and has since worked in several veterinary clinics and hospitals across Singapore and Philippines. Dr. Batanan has a special interest in small animal surgery and is skilled in a range of veterinary procedures including routine check-ups, vaccinations, and surgical operations. She is a dedicated professional who is committed to providing compassionate care to her patients and their families.