What is Myasthenia Gravis in Dogs?

Myasthenia gravis is a neuromuscular disease that causes dogs to become weak. The main hazard is megaesophagus in these dogs because it can be a life-threatening side effect.

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Myasthenia gravis in dogs is a relatively rare neuromuscular disease in which there is a breakdown in the transmission of signals between nerves and muscles. Dogs with myasthenia gravis exhibit extreme weakness and excessive fatigue. The condition keeps muscles from contracting, causing affected dogs to become weak; severe weakness is the primary symptom of myasthenia gravis in dogs.

Certain dog breeds are predisposed to a congenital (inherited) form of myasthenia gravis, including English Springer Spaniels, Jack Russell Terriers, Smooth Fox Terriers and Smooth-haired Miniature Dachshunds. However, most cases are acquired and not inherited, so all puppies and dogs are at risk.

In most cases, myasthenia gravis is an acquired problem in adult dogs. It is thought to be the result of a defect in the dog’s immune system that causes antibodies to mistake the dog’s muscle receptors as the enemy – essentially attacking them and preventing them from working properly. This keeps the muscles from contracting, causing affected dogs to become weak. Female and male dogs are equally at risk.

Miniature Smooth Haired Dachshund.
iStock / Getty Images Plus/ NORRIE3699

“For some reason, we often see peaks of acquired myasthenia gravis in dogs between the ages of two and four, and then again from nine to 13 years of age. Unfortunately, pet parents may think it is just the signs of aging of their senior dog, and not seek out proper diagnosis, management and treatment,” says W. Jean Dodds, DVM, and founder of Hemopet, the first non-profit national animal bloodbank.

Puppies with congenital myasthenia gravis are typically diagnosed at six to eight weeks of age.

The symptoms of myasthenia gravis in dogs are progressive and can vary greatly from dog to dog. The most common symptom is muscle weakness that worsens with exercise, but improves with rest.

Megaesophagus: A Common Result of Myasthenia Gravis in Dogs

Often the esophagus is affected in dogs with myasthenia gravis; these dogs have trouble swallowing and drinking. When a dog’s esophagus loses its motility due to myasthenia gravis, secondary megaesophagus can occur. Megaesophagus is when the esophageal muscle relaxes so that food and liquids cannot be pushed down into the stomach by normal muscle contraction. In some situations, this condition may cause the dog to aspirate food and water, which can in turn result in aspiration pneumonia.

Smooth Fox Terrier
iStock / Getty Images Plus/ derevetskaira

Because megaesophagus can cause aspiration pneumonia, it is a dangerous symptom. Feeding dogs with megaesophagus can be done safely, but it requires some extra effort. Make sure that your dog’s head is elevated during feeding (and for 10 to 15 minutes afterward). Your veterinarian will work with you in finding the best way to make sure your dog can eat and drink without the risk of regurgitation or aspirating food/water.

Diagnosis of Myasthenia Gravis in Dogs

If your dog suffers from muscle weakness, alert your veterinarian at once. The vet will perform a complete physical exam and recommend the best choice of diagnostic testing.

If necessary, your dog will receive treatment specific to his needs. These may include the use of anticholinesterase drugs, which help to improve muscle strength by reducing the attack by antibodies on the dog’s muscle receptors.

Unfortunately, there is no prevention or cure for this disease. Treatment and careful at-home care can help dogs with myasthenia gravis maintain a quality of life for a reasonably long time. The more attention paid to the prevention of aspiration pneumonia, the better the prognosis for your dog.

“Myasthenia Gravis does demand patience and commitment from the pet caregiver,” emphasizes Dr. Dodds. “Remember, it is a progressive condition that does not have a cure, but we can try to slow the progression and side effects with the right supportive care and medications for a longer, quality life.”

17 COMMENTS

    • mestinon is the first line of treatment for Canine MG. 0.5mg/kg – 3mg/kg, BID/TID. If Mestinon alone cannot stabilize, an immunosuppressant is added. I hope this helps.

  1. great article. My dog has has MG/ME for 3 years. We are in remission now but the diagnosis phase was very difficult.. I wish I knew more about MG before diagnosis. This article will be helpful to so many others

    • Hi Jen…I think my dog has myasthenia and trying to diagnose now…she is on mestinon and prednisone now..what do you mean by remission…is your dog fine with no pain? We battled for so long…constant sore knees and back pain…now limping and some days can barely walk.

    • Jen … our dog was diagnosed recently also. He is doing well so far .. just one regurgitation in 3 days following his hospital exit and is gaining his muscle strength back fast. I’m having trouble getting a straight answer on the remission … if your dog is in remission does that mean he can go back to Normal eating and not having to be elevated? I’m trying not to get my hopes up too much but wanted to hear from an owner

      • Sally,

        How are things going with your dog? My cocker spaniel has MG and ME. I would be happy to tell you our story. He has been in remission now for two years i think now after regurgitating multiple times daily, having to hold him up to eat, etc.

  2. Within three days she was diagnosed after some gaging and vometing. Picked her up from the vet with a fairly good prognosis with proper care, she had ME with MG; That evening while holding her upright and administering her steroids, she died while I was holding her upright with my hand supporting her head. Her eyes went blank. I still cannot get over it.

  3. They think my springer spaniel has MG he’s 11 and was healthy up until a few weeks ago but has all the symptoms. He’s off to the vets tomorrow for more bloods I just hope once on meds he improves as is in a very sorry state bit like me at moment too.

  4. My dog (jack russel X pug) who is 10 was recently diagnosed with MG. Her symptoms were a loss of muscle control in her hind legs. When she tried to squat or jump both hind legs would “rabbit hop” in unison, and she fell over on to her side, The hopping continued until she was distracted by being touched or spoken to. Her vet put her on prednisone. The symptoms are gone now My question—has anyone else had experience with this type of MG ?

  5. I just found this on net about MG. I believe my dog has it. I went in twice with my dog all typical symptoms MG. He has no clue, what it was. He said it was arthritis even though muscle wasting swallowing breathing problems developed in a couple of weeks, very acute at age 9. I believe Bravecto either caused it (used over several years) or exacerbated it. Nexguard and Bravecto used at recommended doses and timings. Last dose she showed these symptoms within four days uncoordinated and muscle weakness then exacerbated over four weeks.

  6. Facebook has support groups for MG and ME. We have a doxie that almost died from aspiration pneumonia because of regurgitation. The first sign was hind leg weakness and then progressed to facial and focal paralysis . We feed her upright in a special chair. She is on a drug to treat the symptoms of the MG. Hoping she will go into remission. Check out the groups on Facebook they have been so helpful.

  7. We lost Remy to this last week. The week before I had him out nightly for romps – then one evening after being out he started to throw up. Next 3 days were to an ER vet and then he couldn’t’ stand – next day took him to a neurologist where he was diagnosed and then died 2 days later. Had major problems with his esophagus and breathing at the end. Unbelievable how quick he went from seeming perfectly healthy to passing. We miss him so much. I took him for long romps every night

    • Hello m’y chihuahua was diagnosed with myasthenia not strait away he start with the eyes running for a while then a very bizarre sound from his throat and he couldn’t barked like before and after weeks the most scared was he fell a couple of times so we went to the hospital they said after a scann it was a myasthenia with neurological signs, we are fight for 8months now with 4times to the hospital almost lost him 3 times with pneumonia he is a fighter still with us …. last time we went a month ago because I am aware to everything like vomiting etc… and the neurologist told me he was getting worse so she put the dosage of pyridostigmine up and he was much better we send an other blood test to US and it seems that the antibodies goes a little bit down so we sill very careful with that very bad desease but till then is doing well and I hope we are going on a ride of it (it is a nightmare for months….

  8. My schnauzer was recently diagnosed with ME. Meds are not working. Keep calling the U of I vet for lab results. It’s been over a week. I am at wits end. He will be 2 in Nov. was fine til he got a rabies vaccine in Feb. started throwing up in Mar.
    can someone help here. Ty. Lila and Hasi
    He currently on Viagra and Omeprozole

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