Granulomatous Meningoencephalitis In Dogs

Granulomatous meningoencephalitis (GME) is an acute, nonsuppurative, progressive, inflammatory disease that affects the central nervous system of dogs.

Meningoencephalitis causes the brain to experience inflammation with a focal accumulation of inflammatory cell infiltrate. This is a very serious neurological condition resembling both encephalitis and meningitis or both can happen simultaneously. However, Meningitis and meningoencephalitis treated as two separate conditions.

Meningoencephalitis has a number of potential causes, including both infectious and non-infectious factors such as cancer/paraneoplastic syndromes, autoimmune disorders, and drug reactions. GME can have a diverse clinical presentation depending immune status of the host and age.

The GME pathogenesis is poorly understood but it is currently thought to be a type of lymphoproliferative condition that may develop into lymphoma. GME tends to be more common in young small and medium-sized breeds; however, any breed of any age can be affected.

This condition affects the central nervous system (CNS) which in turn affects all the significant parts of the body. The bad news is when the time your dog starts showing obvious symptoms, such as (convulsions, fever, confusion, etc) it may have already caused permanent damage. But, if the cause of the meningoencephalitis is curable, with appropriate treatment your dog has a chance of recovery.

Initial stage:

• When your dog holding their back or neck rigid- Neck or stiffness in the spine or back pain
• Eyes tracking from side to side or up and down
• Muscle spasms in the forelegs, back, or neck
• Unsteadiness or trouble while walking
• Fever/depression/ Weakness
• Sensitivity to touch
• Vomiting
• Low blood pressure
• Loss of appetite
• Head tilting/ Pacing or circling

Advanced stage:

• Severe unsteadiness or loss of muscle control
• Confusion or disorientation
• Stupor or Dullness
• Blindness
• Abnormal levels of aggression or agitation
• Seizures
• Paralysis

Depending on the cause (infectious or non-infectious cause), your veterinary neurologist may prescribe:

• Steroids: To suppress the immune system and inflammation (prednisone)
• Antibiotics: Antivirals, antifungals, or anti-parasitic medications
• Antiepileptic drugs: Phenobarbital, Potassium Bromide (if the dog is seizing)
• Intravenous fluids: For dehydrated dogs
• Pain medication: NSAIDs
• Analgesics: Such as opioids
• Supportive care: Rest and hospital care for dogs as they fight the disease

Follow the appropriate monitoring schedule for your pet given by the Veterinary neurologist, as recommendations may vary for each individual.

Discuss home treatments with your vet to ensure they’re won’t mess with other medications.

This may include dietary changes, exercise, supplements to administer, and other holistic treatments.

• The bad news is that GME can be caused by several factors, so it is difficult to prevent it.
• Now, the good news is, that this condition is not so common in dogs and there are a few essential ways to help prevent meningitis in dogs.
• Stick to the basics. Follow the guidelines for preventing infections.
• Clean thoroughly any and all wounds, keep recommended vaccinations up to date and administer regular parasite preventatives.
• Regularly perform blood, urine, and fecal screenings.

Beagle, Chihuahua, Bernese Mountain Dog, Dachshund, German Shorthaired Pointer, French Bulldog, Irish Wolfhound, Papillon, Pekingese, Pug, Pembroke Welsh Corgi, Maltese, Nova Scotia Duck Tolling Retriever, Yorkshire Terrier, West Highland White Terrier, Small Dog Breeds, Poodle, Terrier Dog Breeds, Toy Dogs, Middle Age Dogs, Young Dogs

1. Causes:

Infectious GME in dogs:

• Canine distemper virus (viral, contagious multisystemic viral disease)
• Neosporosis (parasitic infection - Neospora Caninum)
• Toxoplasmosis (parasitic infection - Toxoplasma gondii)
• Baylisascaris Procyonis (parasitic- roundworm of raccoons)
• Cryptococcus (invasive fungal infection)
• Blastomycosis (Blastomyces Dermatitidis - yeastlike fungal infection)
• Histoplasmosis (Histoplasma Capsulatum - fungal infection)
• Heartworms (parasitic- Dirofilaria Immitis)

Non-infectious GME causes:

• Non-infectious meningitis is more prevalent in dogs than infectious meningitis.
• Non-infectious meningitis is mostly immune-mediated meningitis.

Steroid-responsive meningitis:

AKA arteritis. This autoimmune condition mostly affects leptomeninges and associated arteries.

2. Types:

1. Infectious Meningoencephalitis:
   • This is caused by viruses, fungi, protozoa, parasites, or bacteria. These are caused by infections that typically begin in some other place in the body, then travel through the bloodstream to the spinal cord and brain.
2. Non-Infectious Meningoencephalitis:
   • Beagle pain syndrome - Juvenile polyarteritis(commonly reported in young beagles).
   • Aseptic meningitis – an overall term used for meningitis with negative cerebrospinal fluid (CSF) bacterial cultures.
   • Pug encephalitis- The medical term is Necrotizing meningoencephalitis. This is a destructive disease with a poor prognosis.
3. Idiopathic and other meningitis:
   • The underlying cause cannot be determined (idiopathic). Other causes include drug allergies, chemical reactions, inflammatory diseases such as sarcoidosis, and some types of cancer.

3. Morbidity:

Risk factors include:

• Undervaccination/ Old age
• Chronic metabolic disorders (diabetes, renal failure, cystic fibrosis, adrenal insufficiency)
• Immunosuppressed states (congenital immunodeficiencies, iatrogenic, transplant recipients)
• Autoimmune hemolytic anemia (AIHA)
• Dogs in crowded conditions such as shelters, rescue homes, etc
• Malignancy
• Splenectomy
• Exposures:
• Travel to endemic areas
• Vectors (mosquitoes, ticks)

4. Diagnosis:

• Blood tests
• Ophthalmic (eye) exam
• Serum biochemistry profile, and urinalysis
• Cerebrospinal fluid (CSF) tap
• MRI and/or CT of the brain

5. Mortality:

GME is a fatal disease with a high case fatality rate and leading to serious sequelae (long-term complications). Mortality rate increases with age.

6. Prognosis:

GME prognosis depends upon the underlying cause. Steroid-responsive GME typically carries a good prognosis. Infectious and immune-mediated GME cases carry a guarded prognosis. Early aggressive treatment can have a favorable outcome in all types of meningitis.

It’s better to set up an appointment with your veterinarian if you notice-

• Confusion or disorientation
• Severe unsteadiness or loss of muscle control
• Abnormal levels of aggression or agitation
• Seizures

1. Elimination phase:

Removal of foods that can cause inflammation

• Remove foods with additives, and refined and processed sugars.
• Trans fats, emulsifiers, thickeners, and food colorings.
• Artificial sweeteners.

2. Maintenance phase:

Gradually cut out grains, legumes, nightshades (potatoes, tomatoes), and dairy.

During the elimination phase, try bland diets to maintain dog metabolism.

Bland diet of one part unseasoned, boiled, boneless, and skinless chicken breast with three parts plain cooked rice.

3. The reintroduction phase

Reintroduced foods one at a time, allowing for a period of 1 week before reintroducing a different food.

• Minimally processed meat: Seafood, organ meat, and poultry; meats should be pasture-raised or grass-fed, whenever possible
• Provide the right fats - Omega-3 fats
• colorful non-starchy vegetables and berries
• Gluten-free diet
• Soups: Broths, chicken soup/stew, fish stew

For dogs with Infectious and immune-mediated GME, the long-term prognosis is generally poor, regardless of treatment. Typically, the dog’s ability to recover from GME will depend on the underlying cause, the duration it is affected and the response to treatment.

Dogs with steroid-responsive GME have a slightly better prognosis, and most of them get well with appropriate treatment.