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smanimalvet, Dog Veterinarian
Category: Dog
Satisfied Customers: 1111
Experience:  Practicing vet with focus on advanced medicine and surgery.
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What would cause muscle atrophy on one side of dogs head

Resolved Question:

What would cause muscle atrophy on one side of dogs head
Submitted: 7 years ago.
Category: Dog
Expert:  smanimalvet replied 7 years ago.

Hi there-


A couple of quick questions:

1. Is there any muscle loss anywhere else?

2. Is there any pain?

3. Which side of the head?

4. Is he on flea and tick preventative?

5. Any neurologic signs at all? Drooping of the eyelid, face, etc. Dropping of food? Can't see out of the eye ont he side of the face that is affected?


Dr. B

Customer: replied 7 years ago.
1. No muscle loss anywhere on Jake except behind his left eye at the forehead area. The other side of his l head is normal. 2. He does not seem to be in pain. In fact when I touch that area he rubs his head on me like he wants me to rub it. 3. left side of head. 4. Jake is on revolution but we have had a terribel tick season in Florida. I had the yard treated it was so bad. We also have other dogs and none of them are like Jake with a problem as such. 5. the left eye lid is droopy but I think it is because the muscle is gone. No food is dropping out and he dea eats and drinks normally. He is not loosing weight. He seems to be seeing fine. He is a little restless and I think this area bothers him
Expert:  smanimalvet replied 7 years ago.

Ok great! Thanks for the extra information.


The muscle you are describing is called the temporal muscle. Since this is the only place that is affected, we have to assume there is something wrong with the nerve that innervates that area only. When we lose innervation to a muscle, the muscle will waste away very quickly. The nerve that innervates that muscle is called the trigeminal nerve. The things that can affect the nerve supplying a particular muscle are trauma, infection, or cancer (particularly a nerve sheath tumor).


The disease you read about is called Masticatory Muscle Myositis. This means inlammation of the muscles of mastication (chewing). This usually doesn't affect just one side of the face but it is possible. This is an autoimmune disease and something I think should be considered here. There is a test called a 2M titer test I believe.


If that test comes back normal, you may want to consider a CT or MRI of the area to get a definitive diagnosis though I am not 100% sure if treatment options would be available. If you decide to go that far, it might be worth it to see a specialist in neurology.


For what it is worth, I have seen one or two of these situations respond with the use of steroids regardless so that might be another option!


Hope that helps!

Dr. B

Customer: replied 7 years ago.
I think we have nothing to loose in trying a steroid. Jake also takes thyroid medication but I don't think this is related whatsoever. I will call my vet tomorrow. If Jake had a tumor I think I would be seeing neurological signs but I cannot say that I am. I might as k for him to be examined under anesthesia carefully in that left ear. I thought about ticks before but figured if he were on Revolution then even if there were ticks they would die when they bit him. I think I am right on that. I will s also talk to the vert about the 2M titer test, what do we have to loose. We love him and he is wonderful. Thanks for your help, I appreicate it.
Expert:  smanimalvet replied 7 years ago.

You're very welcome. The thing about the neurologic signs (which we aren't seeing) is that if there is a tumor of just that nerve, this might be the only sign we see. The good news with that, however, if that it likely will never cause a problem outside of the muscle loss. You are spot on with the revolution.


I wish you luck!!

Expert:  smanimalvet replied 7 years ago.
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