What is Myasthenia Gravis in Dogs?
Myasthenia Gravis in dogs is an autoimmune disease that impacts the neuromuscular junction in canines, cats, and humans. It is caused by a breakdown of acetylcholine (ACh) receptors, which are basically linked to the transmission of impulses from nerves to the muscles. This condition causes severe muscle weakness throughout the body.
Canine Myasthenia Gravis commonly affects adult dogs. However, in some rare cases, puppies can inherit the disorder due to congenital defects. Some dog breeds are more at risk for the disease than others.
These dog breeds include the following:
- Jack Russell terriers
- Scottish terriers
- Springer spaniels
- Smooth Fox terriers
- German Shepherd
- Great Dane
- Golden Retriever
- Labrador Retriever
- Smooth-haired Miniature Dachshunds
Myasthenia Gravis Symptoms in Dogs
Muscle Weakness in Dogs
Myasthenia Gravis can cause different symptoms amongst dogs. The most common symptom of this disorder is muscle weakness. This is because the breakdown of the neuromuscular junction affects skeletal muscles. In many cases, muscle weakness appears to worsen during periods of physical activity, such as running, walking, and playing, and seems to improve during rest periods.
Dogs that suffer with Myasthenia Gravis may also have difficulty swallowing and drinking. This is due to the swelling of the esophagus. Some regurgitation is also common. In severe cases, some dogs will even regurgitate or aspirate their food and water, causing aspiration pneumonia.
Here is a complete list of the most common symptoms and clinical signs of Myasthenia Gravis in dogs:
- Muscle weakness while exercising
- Collapsing or general weakness
- Droopy eyelids
- Sleeping with eyes open
- Excessive drooling
- Regurgitating food and/ or water
- Persistent barking or whining
- Aspiration pneumonia
- Difficulty swallowing (or excessive swallowing)
- Difficulty breathing (a common sign of aspiration pneumonia)
- Excessive coughing (a common sign of aspiration pneumonia)
Causes of Myasthenia Gravis in Dogs
The specific causes of Myasthenia Gravis in dogs have been researched by professional veterinarians for years. The most common causes of the disease include the following:
- A breakdown or reduction in the transfer of nerve impulses to muscles.
- A deficiency of acetylcholine, which affects muscle movement.
- A congenital defect that some dog breeds inherit at birth.
- An acquired or immune-mediated disorder that involves the destruction of receptors by antibodies.
Congenital Myasthenia Gravis vs. Acquired Myasthenia Gravis
So, what exactly causes Myasthenia Gravis in dogs? As we briefly mentioned above, there are two main types of myasthenia gravis in dogs: acquired and congenital. Myasthenia gravis in dogs is often acquired rather than inherited at birth (congenital).
Congenital Myasthenia Gravis is incredibly rare, but it can happen. Puppies born with an ACh-receptor (acetylcholine receptors) deficiency are likely to have congenital Myasthenia Gravis. Congenital Myasthenia Gravis typically becomes apparent in puppies that are approximately six to eight weeks old. In severe cases of Congenital Myasthenia Gravis, puppies can experience paralysis or even death.
Acquired Myasthenia Gravis typically appears in dogs that are between two and four years old. Acquired Myasthenia Gravis in dogs is an immune-mediated disease, which is when the dog’s own antibodies destroy ACh-receptors, causing an acetylcholine receptors deficiency. The Dachshund is the most common dog breed that contracts Congenital Myasthenia Gravis. Perhaps what is most interesting is that Congenital Myasthenia Gravis in Dachshunds often resolves on its own!
Myasthenia Gravis Treatment in Dogs
The good news is that Myasthenia Gravis can be treated. There are various treatment methods, which include both traditional medicine as well as an at-home holistic approach. The most common treatment is the use of anticholinesterase drugs. These particular drugs contain a nervous system enzyme that helps prevent antibody attacks. These drugs also help to improve muscle strength, allowing the dog to move his or her muscles with ease.
In some severe cases of Myasthenia Gravis, dogs may be hospitalized until they are stabilized with Anti-acetylcholinesterase medications. Some dogs may require Anti-acetylcholinesterase medications for the rest of their lives. Acetylcholine can also be used to help treat dogs with myasthenia gravis.
Furthermore, the acetylcholinesterase enzyme will often break down acetylcholine. Therefore, drugs that promote acetylcholine are also used to help treat this neuromuscular disease. Pyridostigmine bromide is a common drug that promotes the action of acetylcholine.
A Holistic Approach
If your dog suffers with Myasthenia Gravis, and you prefer to approach it holistically, then be sure to discuss this with your vet. Your vet will talk to you about the best methods that he or she believes are best for your dog. One of the best ways to help treat Myasthenia Gravis in dogs is by supporting them with proper nutrition.
Dogs with Myasthenia Gravis should consume smaller meals and more frequently. Meals should be high in calories in order to ensure your dog is getting sufficient nutrition. There isn’t a “one-size-fits-all” diet for dogs with Myasthenia Gravis so be sure to speak with your vet about the best diet for your dog.
Because dogs with this disease often have difficulty using the esophagus and swallowing food and water, they need to be fed and monitored carefully. You can help by simply adjusting the dog’s feeding bowls, preventing him or her from having to bend down to eat or drink. After the dog finishes eating, hold him or her for approximately 20 minutes to prevent regurgitation and aspiration pneumonia. It will also help your dog get the proper nutrition he or she needs to treat the condition.
Aspiration pneumonia is a severe side effect from this disease. In fact, it can often require intensive care, hospitalization, and even IV fluid therapy. A feeding tube may also be required to give the dog sufficient nutrition and fluids until medications are stabilized. Therefore, working with your vet and doing what you can at home to help prevent aspiration pneumonia will ensure that your dog stays as healthy as possible and gets the proper nutrition to fight the disease.
Myasthenia Gravis: Other Complications
In severe case of Canine Myasthenia Gravis, cancer may develop. In fact, tumors, also known as thymoma can develop, which originate on the tissue of the thymus gland—an organ near the heart. Although thymoma tumors are rare in cats and dogs, they are mostly associated with Myasthenia Gravis.
What is Megaesophagus?
Megaesophagus is a condition that involves the enlargement of the esophagus, which is the tube that connects the throat to the stomach. Dogs that suffer with Megaesophagus often have a decreased ability to move food and fluids down into the stomach. Therefore, pet owners that notice their dog having difficulty swallowing food or water may mistake Megaesophagus with Myasthenia Gravis—or vice versa. A vet will often perform an evaluation to determine if a dog has Megaesophagus or Myasthenia Gravis.
Megaesophagus is more common in dogs than cats. Similar to Myasthenia Gravis, some dog breeds are more prone to contracting Congenital Megaesophagus than others. The dog breeds that are predisposed to this condition include the following:
- Fox terriers
- Miniature schnauzers
- German Shepherds
- Great Danes
- Irish setters
- Labrador retrievers
- Chinese shar-pei
Myasthenia Gravis Diagnosis
If you believe your dog is displaying clinical signs or symptoms of Myasthenia gravis or Megaesophagus, then it’s important to call your vet immediately. A professional vet will perform various tests to diagnose the correct disease. Some tests can include the following:
- A physical exam
- A blood test (antibody titer test, which tests the number of antibodies in the blood)
- A Tensilon test (an edrophonium test, an anti-acetylcholine receptor antibody test, or an anti-achr antibodies test)
- Chest X-rays
The best way to test a dog for the presence of Myasthenia Gravis is to perform a blood test, that is also ACHr antibody test, which checks for the presence of an acetylcholine receptor antibody.
Tensilon Test for Dogs
If your dog is showing clear signs of muscle weakness, then your vet may issue a special test, known as a Tensilon test. With this particular test, a dog is given an injection of an acetylcholinesterase inhibitor known as edrophonium chloride. If the dog experiences a temporary improvement in muscle movement and a reduction in weakness, then the dog likely has Myasthenia Gravis. This particular test is also referred to as an anti-acetylcholine receptor antibody test.
All in all, it is incredibly important for a vet to rule out other diseases, disorders, or injuries before diagnosing a dog with Myasthenia Gravis. This neuromuscular disorder can be a life-changing disease for your dog, so getting a firm diagnosis and forming a sufficient treatment plan is crucial for your dog’s survival.
In some cases, a vet may recommend pet owners to visit veterinary specialists to help make a firm diagnosis.
Myasthenia Gravis Prognosis
Unfortunately, you cannot prevent acquired nor congenital Myasthenia Gravis in dogs. However, much like people with Myasthenia Gravis, the disease is entirely treatable, but it will require long-term, at-home support and care until muscle weakness is reduced. The more attention and care you give to your dog, the more likely he or she will be able to maintain a strong, healthy, and happy quality of life.
My dog has Myasthenia Gravis! Can I treat them holistically or do I have to rely on pharmaceuticals?