Infectious brain disorders in pets - Causes, symptoms & treatment

Infectious brain disorders are caused by pathogens such as parasites, bacteria, viruses, or fungi that invade the brain and/or its surrounding membranes. These infections lead to inflammation of the brain tissue and meninges (encephalitis or meningoencephalitis), which can cause severe neurological symptoms. In dogs and cats, feline infectious peritonitis virus (FIP), toxoplasmosis, neosporosis, and bacterial infections are the most common causes. 

In this article, we discuss the causes, symptoms, diagnosis, treatment, and prognosis of infectious brain disorders in pets.

What are infectious brain disorders?

Infectious brain disorders are inflammations of the brain or meninges caused by pathogens. These can reach the brain through the bloodstream, from a nearby infection (such as an ear or nasal infection), or directly following trauma or surgery. These infections often cause severe symptoms and require prompt treatment.

Which animals are at risk?

Both dogs and cats are at risk, especially during periods of reduced immunity - for example, very young kittens and puppies, or aged, weakened animals.

Causes of infectious brain disorders

The main infectious causes are:

• Parasitic infections: Toxoplasma gondii (cats), Neospora caninum (dogs)
• Bacterial infections: often following ear infections, nasal infections, or blood poisoning
• Viral infections: in dogs, including canine distemper virus; in cats, including FIP
• Fungal infections: rare, usually in immunocompromised animals or animals with fungal infections in the nose that spread further toward the brain

Symptoms in dogs and cats

Symptoms vary depending on the pathogen, but common signs include:

• Ataxia (unsteady gait)
• Weakness or paralysis
• Balance disorders
• Epileptic seizures
• Behavioral changes/changes in consciousness
• Fever and lethargy

Diagnosis of infectious brain disorders

The diagnosis is made through a combination of clinical and neurological examination, blood tests, and imaging. MRI and CT reveal areas of inflammation. Cerebrospinal fluid analysis provides evidence of inflammation and can sometimes identify the causative pathogen.

Treatment of infectious brain disorders

Medication

Treatment depends on the cause:

• Toxoplasmosis/Neosporosis: antibiotics such as clindamycin
• Bacterial infections: targeted antibiotics based on culture results
• Viral infections: supportive care; antiviral therapy is limited, but an effective therapy for FIP has recently become available
• Fungal infections: antifungal medication, though the prognosis is often guarded

Supportive therapy

In addition to specific medication, animals often receive pain relief, anti-inflammatory drugs, and anti-epileptic drugs if needed. Physiotherapy and rehabilitation can help with the recovery of muscle strength and coordination.

Recovery and prognosis

The prognosis varies greatly depending on the pathogen and how quickly diagnosis and treatment occur. Bacterial and viral infections often have a variable prognosis. Fungal infections in the brain usually have a guarded to poor prognosis.

Want to know more?

Read more about our services in neurology and internal medicine. Our specialized veterinarians at Nesto have experience with infectious brain disorders and guide you and your pet through the treatment and recovery process.

Frequently Asked Questions (FAQ)

What are infectious brain disorders?

Inflammations of the brain or meninges caused by pathogens such as parasites, bacteria, viruses, or fungi.

Which animals are at risk?

Both dogs and cats.

How is the diagnosis made?

With blood tests, imaging (MRI/CT), and cerebrospinal fluid analysis.

How are they treated?

With antibiotics or antiprotozoal agents depending on the cause, supplemented with supportive care.

What is the prognosis?

Depends on the pathogen and how quickly treatment begins.