Meningitis

Meningitis is an inflammation of the meninges, the membranes surrounding the brain and spinal cord. The disease is triggered by infections or autoimmune processes and causes severe pain as well as neurological symptoms. If left untreated, meningitis in dogs can become life-threatening.

Definition and Distinction

Meningitis denotes an inflammation of the meninges, which protect the central nervous system. The inflammation irritates the meninges, triggers pain and leads to neurological symptoms. Meningitis can occur in isolation or together with encephalitis (brain inflammation); this is then referred to as meningoencephalitis.

Causes of Meningitis in Dogs

Meningitis arises from infectious or non-infectious factors:

Infectious Causes:

• Bacterial infections: Bacteria infect the meninges directly or spread from the ears, sinuses, or via the bloodstream. Common pathogens include Streptococcus, Staphylococcus, or E. coli.
• Viruses: Distemper and Rabies can lead to inflammation of the meninges.
• Fungal infections: In rare cases, Cryptococcus affects the central nervous system.
• Parasites: Neospora caninum or Toxoplasma gondii can cause inflammation of the meninges.

Non-infectious causes:

• Steroid-responsive Meningitis-Arteritis (SRMA): An autoimmune inflammation in which the immune system attacks blood vessels in the meninges. SRMA responds well to corticosteroids.
• Granulomatous meningitis: A chronic inflammation with granulomas (inflammatory cells) in the meninges and brain.
• Trauma or injuries: Head or spinal cord injuries can trigger an inflammatory reaction in the meninges.

Symptoms of meningitis in dogs

The symptoms vary depending on the severity of the inflammation and the areas of the central nervous system affected:

• Fever: Elevated body temperature occurs particularly with bacterial or viral meningitis.
• Neck stiffness and pain: The dog shows painful neck stiffness, holds its head low, and avoids being touched.
• Lethargy and fatigue: Affected dogs are unusually tired.
• Loss of appetite: Food intake is reduced or has stopped completely.
• Changed behaviour: Irritability, confusion, or disorientation; in severe cases, aggression or apathy.
• Seizures: Seizures occur particularly when the inflammation affects the brain.
• Balance problems and coordination disorders: Staggering, difficulty walking, loss of balance.
• Sensitivity to touch: Touching the head or neck causes severe pain.

Diagnosis of meningitis in dogs

The diagnosis requires a thorough examination and specialised tests:

1. Clinical examination: The vet assesses symptoms such as neck stiffness, fever, and neurological abnormalities.
2. Blood tests: Blood tests provide indications of an inflammatory reaction in the body.
3. Cerebrospinal fluid analysis (CSF analysis): Cerebrospinal fluid (CSF) is collected via a lumbar puncture and examined for inflammatory cells, bacteria, viruses, or signs of an autoimmune disease.
4. Imaging techniques: MRI or CT scans visualise inflammation in the meninges or brain areas and rule out tumours, abscesses, or structural problems.
5. Bacterial cultures and serological tests: Culture tests identify the specific pathogen in bacterial or viral meningitis. Serological tests rule out parasitic or viral causes.

Treatment of meningitis in dogs

Treatment depends on the cause of the disease:

1. Antibiotics: In bacterial meningitis, broad-spectrum antibiotics are administered. The choice depends on the culture test results.
2. Corticosteroids: In non-infectious meningitis, particularly SRMA, corticosteroids such as prednisolone are used to reduce inflammation and suppress the immune system. Symptoms often improve within a few days.
3. Antiviral or antifungal medications: Specific antiviral or antifungal medications are used for viral or fungal infections.
4. Pain and seizure management: Painkillers relieve pain associated with neck stiffness and inflammation. Anticonvulsants are administered for seizures.
5. Fluid therapy: Intravenous fluid administration stabilises dehydrated or weakened dogs.

Prognosis for meningitis

The prognosis depends on the cause, the speed of diagnosis, and the response to treatment:

• Infectious meningitis: With early treatment, the prognosis for bacterial meningitis is often favourable. If left untreated, severe neurological damage or death may occur.
• Autoimmune meningitis: Dogs with SRMA or other autoimmune forms generally respond well to corticosteroids but may require long-term therapy to prevent relapses.
• Viral and fungal infections: The prognosis varies depending on the severity of the infection and general health status.

Prevention

Prevention depends on the cause. For infectious forms, regular vaccinations against rabies and distemper provide protection. Good hygiene and regular vet check-ups help detect and treat bacterial infections early.