Meningitis, Meningoencephalitis, Meningomyelitis in Dogs

By PetMD Editorial on Feb. 14, 2010

Bacterial Meningitis and other Nervous System Infections in Dogs

Much like in humans, the system of membranes which envelops the dog's central nervous system is called the meninges. If this system becomes inflamed, it is referred to as meningitis. Meningoencephalitis, meanwhile, is the inflammation of the meninges and brain, and meningomyelitis is the inflammation of the meninges and spinal cord.

Inflammation of meninges commonly leads to secondary inflammation of the brain and/or spinal cord, resulting in various neurological complications. Long-term inflammation can also obstruct the flow of cerebrospinal fluid (CSF) -- the protective and nourishing fluid that circulates around the brain and spinal cord -- which leads to accumulation of CSF in the brain and thus severe complications such as seizures and paresis.

Symptoms and Types

Neurological symptoms often associated with meningitis, meningoencephalitis, and meningomyelitis such as impaired movement, altered mental state, and seizures, may be profound and progressive. Other symptoms generally seen in dogs suffering from one of these conditions include:

Depression
Shock
Low blood pressure
Fever
Vomiting
Abnormal increase in sensitivity to various stimuli (hyperesthesia)

Causes

The most common cause of meningitis is a bacterial infection in the brain and/or spinal cord originating from elsewhere in the body. Meningoencephalitis, meanwhile, is usually due to infections of the ears, eyes, or nasal cavity. And meningomyelitis generally proceeds following diskospondylitis and osteomyelitis. In puppies and dogs with compromised immune system, such infections commonly reach the brain and spinal cord via the blood.

Diagnosis

You will need to give a thorough history of your dog’s health, including the onset and nature of the symptoms. The veterinarian will then conduct a complete physical examination and several laboratory tests -- such as complete blood count (CBC), blood culture biochemistry profile, and urinalysis -- to help identify and isolate the type of infection.

Biochemistry profile, for example, may indicate liver and kidney involvement, while blood testing may reveal an increased number of white blood cells, which is evidence of an ongoing infection. Urinalysis may also reveal pus and bacteria in the dog's urine, an indication of urinary tract infections.

Other tools often used to identify the infectious agent involved include magnetic resonance imaging (MRI), abdominal ultrasounds, thoracic and abdominal X-rays, and samples from the skin, eyes, nasal discharge, and sputum.

One of the most important diagnostic tests, however, is CSF (or cerebrospinal fluid) analysis. A sample of your dog's CSF will be collected and sent to a laboratory for culturing and further evaluation.

Treatment

In severe cases of meningitis, meningoencephalitis, or meningomyelitis, the dog will be hospitalized to prevent more severe complications. Once the causative organism is identified, your veterinarian will employ antibiotics intravenously to maximize their effectiveness. Antiepileptic drugs and corticosteroids may also be prescribed to control seizures and reduce inflammation, respectively. Dogs that are severely dehydrated, meanwhile, will undergo immediate fluid therapy.

Living and Management

Rapid and aggressive treatment is vital for a successful outcome, although its effectiveness is highly variable and overall prognosis is not favorable. Unfortunately, many dogs die from these type of infections once it reaches the central nervous system, despite treatment.

However, if treatment is successful it may take more than four weeks for all the symptoms to subside. The dog's activity should be restricted during this time and until it is stabilized.