Meningoencephalomyelitis in Dogs

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Meningoencephalomyelitis is a compound word that indicates inflammation of the meninges (coverings of the brain and spinal cord), encephalo (brain tissue itself) and myelo (spinal cord tissue). The '–itis' part of the term simply refers to the inflammation which can be infectious or non-infectious.

The roots of this term can be combined to indicate inflammation of the meninges and brain (meningoencephalitis), meninges and spinal cord (meningomyelitis) or brain and spinal cord (encephalomyelitis).

Meningoencephalomyelitis is an uncommon syndrome but can be seen in any aged animals often with devastating results.

There are numerous potential causes of meningoencephalomyelitis. Infectious causes include viruses, bacteria, fungus or parasites. When a specific cause of meningoencephalomyelitis is not found, it is called idiopathic, which means it has no known cause, although unidentified viral and immune-mediated causes are commonly suspected.

What to Watch For

Symptoms that indicate encephalitis include:

  • Lethargy
  • Fever
  • Disorientation
  • Stupor
  • Seizures
  • Unsteady gait
  • Behavior changes
  • Anorexia
  • Photophobia (sensitivity to light)

    Symptoms of meningitis may include:

  • Same as encephalitis
  • Irritability
  • A stiff neck or back

    Symptoms of myelitis may in include:

  • Stumbling
  • Falling
  • Uncoordinated gait
  • Paresis (weak voluntary movement)
  • Paralysis

    If the following symptoms are seen, they may indicate an emergency situation that should be addressed immediately:

  • Seizures
  • Loss of consciousness
  • Altered consciousness such as stupor or inappropriate responses
  • Paralysis

    Diagnosis

    Your veterinarian will perform a complete physical and neurologic examination and may order some additional tests such as:

  • Complete blood count or hemogram
  • Serum chemistry analysis
  • Urinalysis

    Depending on the results of the individual tests above, other tests may be required and could include:

  • Neuroimaging (CT and/or MRI)
  • Cerebrospinal fluid tap
  • Electroencephalogram
  • Bacterial and viral culture of cerebrospinal fluid
  • Serological testing of the blood

    Treatment

    The general goals of treatment are to provide supportive care and relieve symptoms. Specific treatment is indicated when a cause can be determined. Treatment may include:

  • Anticonvulsants to treat seizures
  • Corticosteroids to reduce brain swelling and inflammation
  • Non-steroidal anti-inflammatory medications to reduce fever and pain
  • Supportive care, such as rest, nutrition and fluids

    Home Care

    If your pet has been diagnosed with meningoencephalomyelitis, follow your veterinarian's treatment recommendation and notify him if any symptoms worsen or emergency symptoms appear. Keep your pet well-rested, warm and well fed following the illness.

    The outcome will vary. Some animals may recover and other may not survive the disease.

  • There are numerous causes of meningoencephalomyelitis including:

  • Some specific diseases, which have one or more components of meningoencephalomyelitis, include granulomatous meningoencephalomyelitis, pug dog meningoencephalitis and necrotizing meningoencephalitis of Yorkshire terriers and Maltese dogs.

  • Infectious causes may be viral, bacterial, fungal or parasitic and are identified by either direct observation of the organism in the cerebrospinal fluid (CSF), culture of the CSF or serologic testing of the blood, CSF or other body fluid affected by the pathogen.

  • Exposure to virus can occur through insect bites, food, water, skin contact or decomposing material.

  • Rickettsial and arbovirus diseases can be carried by mosquitoes or ticks while protozoal diseases such as neospora and toxoplasmosis are spread by fecal contamination.

  • When a specific cause of meningoencephalomyelitis is not found, it is called idiopathic, which means it has no known cause, although unidentified viral and immune-mediated causes are commonly suspected.

  • If an infectious cause invades the brain, it can cause inflammation of the brain, spinal cord and coverings. White blood cells invade the brain tissue as they try to fight off the infection. The brain tissue swells and can cause destruction of nerve cells, bleeding within the brain and brain damage.

  • Diagnosis In-depth

    Your veterinarian will perform a complete physical and neurologic examination and may order some additional tests:

  • Complete blood count or hemogram allows your veterinarian to know the extent of the disease process and occasionally yields a diagnosis.

  • Serum chemistry analysis can help assess the body's overall health status and may assist in choosing specific tests. For instance, toxoplasmosis, neosporosis and mycoses will cause the globulins in the serum chemistry analysis to be markedly elevated.

  • Urinalysis to assess kidney function and check for organisms in urine.

    Depending on the results of the individual tests above, other tests may be required and could include:

  • Neuroimaging (CT and/or MRI) will assess the brain and/or spinal cord for compressive lesions as well as changes in the parenchyma of the neural tissue. A prognosis based on the morphologic changes in the neural tissue is possible, although tissue diagnosis may be the best.

  • A myelogram or myelogram and CT may help diagnose compressive lesions in the spinal cord, although these tests will not assess parenchymal damage in the brain and spinal cord.

  • X-rays of the chest and abdomen.

  • Cerebrospinal fluid (CSF) tap is the most powerful tool to determine the presence of inflammation in the neural tissue. It will occasionally give us a complete diagnosis as in the cases of mycotic diseases if the organism is seen directly in the sample.

  • Electroencephalogram can assess the electrical activity in the brain.

  • Bacterial and viral cultures of CSF.

  • Serological testing of the blood.

  • Neuroimaging and CSF tap procedures require general anesthesia, which has risks for sick animals.

    Treatment In-depth

  • The general goals of treatment are to provide supportive care and relieve symptoms.

  • Specific treatment is indicated when a cause can be determined.

  • Broad-spectrum antibiotics may be prescribed for bacterial infections. Oftentimes, your veterinarian will choose an antibiotic empirically before a final culture and sensitivity is returned. A different antibiotic may be added if the culture indicates it.

  • Anticonvulsants may be given to treat seizures. Some anticonvulsants include phenobarbital, potassium bromide, chlorazepate, valproic acid, gabapentin, felbamate and lamotrigine. Diazepam (valium) is used for emergency or short term use.

  • Following inflammation, a scar may form on the brain and may be a predisposing factor for seizure disorders even after your pet has completely recovered from the initial illness.

  • Corticosteroids, such as dexamethazone or prednisone, are used to reduce cerebral edema and inflammation. Corticosteroids should be avoided if there is an active bacterial infection causing the inflammation.

  • Non-steroidal anti-inflammatory drugs are used to reduce fever and pain.

  • Supportive care (rest, nutrition, and fluids) allows your pet to fight the inflammation. If your pet cannot tolerate medications, food, or fluids orally, some of these things can be given intravenously.

  • If seizures develop during or after the meningoencephalomyelitis, anticonvulsants such as phenobarbital can be given to treat these disturbances.

    Follow-up

    If your pet has been diagnosed with encephalomeningomyelitis or any variant, follow all treatment recommendations and notify your veterinarian if any symptoms worsen or emergency symptoms appear. Keep your pet well-rested, warm and well fed following the illness.

    The acute phase of this disease may last for 1 to 2 weeks with resolution of fever and neurologic symptoms. Some neurologic symptoms may require many weeks or months before full recovery is seen.

    The outcome of meningoencephalomyelitis varies. Some cases are mild, brief, and have complete recovery. Others are severe and protracted with permanent damage. Death is possible.

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