Meningitis is an inflammation of the meninges, which is the fibrous covering of the brain and spinal cords. There are many causes of meningitis including viral, bacterial, fungal and immune mediated.

Aseptic meningitis is believed to be an immune-mediated disease although the exact cause is unknown. The meninges become inflamed and thickened with an invasion of inflammatory cells. This usually occurs in the neck. The signs that your pet reflect the location of the inflamed meninges and vary from mild neck discomfort to severe cervical rigidity and intractable pain. Fever may accompany the signs of pain.

It is most frequently seen in medium to large breed dogs. Dog breeds that are seen most often are:

Labrador retrievers

Golden retrievers

Bernese Mountain dogs

Weimaraners

German shepherd dogs
        
Aseptic meningitis usually affects dogs younger than two years old with both male and female dogs equally affected.

Aseptic meningitis may be the most common form of meningitis seen in dogs. Dogs affected by aseptic meningitis usually do not show other signs of bacterial meningitis. Other conditions that can cause similar signs include:

Viral meningitis. This form can be caused by canine distemper, adenovirus, or rarely parvovirus.

Bacterial meningitis. Although rare, Staphylococcus intermedia, streptococcus, Escherichia coli and Pasteurella multocida are all bacteria that can cause bacterial meningitis.

Other infections causes of meningitis include Rickettsia (Rocky Mountain Spotted Fever), fungus (Cryptococcus neoformans) and parasites. These can cause meningitis but usually have other signs of illness.

Brain tumors. Tumors of the forebrain can cause neck stiffness or pain.

Hydrocephalus and syringomyelia. These are congenital (present at birth) conditions typically seen in smaller dog breeds.