Meningoencephalitis in Dogs

Meningoencephalitis is a painful and debilitating disease that can be caused by anything that precipitates inflammation anywhere in the body. Some of these are infected wounds, sinuses, or ears that migrate to the brain, toxic chemical exposure, insect bites (ticks or mosquitos usually), untreated streptococcus, E. coli infection, and staphylococcus infections, and sometimes it is just spontaneous, although that is rare. Some of the first signs of meningoencephalitis are extreme sensitivity to touch, stiff muscles, and stumbling.

Meningoencephalitis is actually a merging of two illnesses that often occur together in dogs. Meningitis is the inflammation of the meninges, which is the outer layer of the brain and spinal cord. Encephalitis is the inflammation of the brain. These are dangerous disorders when they occur separately, so they are twice as serious when they occur together. This disease affects the central nervous system (CNS) which affects all the vital parts of the body. Unfortunately, by the time your dog starts showing obvious symptoms, such as fever, confusion, and convulsions, it may have already done irreparable damage. But, if the source of the meningoencephalitis is one of the curable causes, with aggressive treatment your dog has a chance if you get to a veterinary professional right away.

The symptoms are usually pretty extreme by the time you notice them which is what makes meningoencephalitis such a dangerous illness. Once the main CNS symptoms are evident, the disease has already done some damage to the nervous system and it may be too late for treatment. However, with aggressive treatment, it is always possible. Watch for these signs of illness:

• Increased body temperature
• Rigid stance
• Neck pain (holding the head very stiff)
• Depression
• Loss of balance
• Lack of motor control
• Disorientation
• Weakness
• Abnormal behavior
• Irritation and nervousness
• Tilting the head
• Sensitivity to touch
• Lethargy
• Muscle spasms
• Walking in circles
• Loss of appetite
• Blindness
• Partial paralysis (usually in the legs or face)
• Seizures
• Fainting
• Coma
• Death (common mortality rate between 60% and 100%, depending on the source)

Types

The different types of meningoencephalitis are similar to the causes of the disease, which are:

• Immune system meningoencephalitis – The body attacks its own cells, which causes inflammation of the nerves
• Bacterial – Eye, ear, or sinus infection, infected wound
• Viral – Rabies, distemper
• Fungal - Blastomycosis
• Parasitic - Trichinosis
• Rickettsial – Ehrlichia, Rocky Mountain spotted fever, lyme disease
• Protozoan - Toxoplasmosis
• Idiopathic – Unknown

All dogs of any age and gender are susceptible to meningoencephalitis, but there are certainly some groups of animals that are higher risk. These are:

• Puppies under three months of age and dogs above eight years old because of their low immune system
• Certain breeds (Pug, Maltese, Bernese Mountain dog, and Beagle)
• Dogs with chronic diseases because of their lowered immune system

If you believe your dog could have meningoencephalitis, you need to go to the nearest animal hospital or emergency clinic. Be sure to call ahead to let the staff know that your dog may have a contagious form of meningoencephalitis, just in case. That way, they can make arrangements for you to take your pet directly to a private room so as not to infect the other animals. The veterinarian on duty will talk to you at length about your dog’s medical history and immunization records and why you believe your dog has meningoencephalitis. Be sure to let the veterinarian know if your dog is on any kind of medication, whether it is a prescription or not. This is important because it may affect the diagnosis and the treatment plan.

A comprehensive medical examination will be done to assess your dog’s overall health, body temperature, weight, height, reflexes, pupil reaction time, respiration and heart rate, blood pressure, and breath sounds. The most important test in this case is the spinal tap, in which the veterinarian will place your dog under anesthesia and take a sample of cerebrospinal fluid to analyze. The results of the test will likely show an increase in protein, globulin, and white blood cells if your dog has meningoencephalitis. Other tests that may be needed are a complete blood count (CBC), serum biochemical analysis, blood urea nitrogen (BUN), and packed cell volume (PCV). Imaging, such as x-rays, CT scans, and MRI may be necessary as well.

To treat your dog for meningoencephalitis, the cause has to be determined. There are different procedures and types of medications for each cause.  

Fluids and Oxygen

Your pet will be given intravenous (IV) fluids and electrolytes for dehydration and to boost the metabolism.

Medication

Some of the medicines the veterinarian may give your dog are corticosteroids, antibiotics (cephalosporins, fluoroquinolones, sulfonamides, metronidazole, tetracyclines, and ampicillin), antifungal medication, pain medication for discomfort, itraconazole or fluconazole for mycotic infection, clindamycin and anticonvulsants to control seizures.

Hospitalization

Your dog will be kept for at least 24 hours for treatment and observation. Since the mortality rate is so high, the veterinarian may let you take your pet home right away and just give you medication for pain. If your dog is obviously suffering, though, your veterinarian may suggest euthanizing your dog.

The prognosis for meningoencephalitis is not promising. In fact, this is usually fatal within just a few days or weeks because once your dog shows symptoms it is already affecting the CNS. However, this depends on the cause of the meningoencephalitis. If the cause is immune-related or bacterial, the chances for successful recovery are not good, but possible with continued aggressive treatment. Viral infections show a high mortality rate at 60% to 85%, but if your dog can handle the treatment, the disease may be beaten. No matter what the cause, if your dog is in severe pain and no chance of recovery, euthanasia may be the only choice.