Brain inflammation in dogs: Everything you need to know about canine encephalitis

Encephalitis, or inflammation of the brain, is not a disease on its own but a serious complication that can occur with many different illnesses. It’s a significant clinical finding and is associated with symptoms such as seizures, disorientation, blindness, loss of coordination, and other sudden changes in movement, awareness, or behavior.

These changes can be frightening for pet owners to see, and it’s natural to search online for answers. But it’s important to know that sudden neurologic symptoms and dramatic changes in behavior are emergencies requiring immediate, in-person veterinary care. Early recognition of the significance of neurologic signs and prompt veterinary care may improve prognosis.

You can be better prepared to act quickly in an emergency by learning:

• How dogs get encephalitis
• The common clinical signs of encephalitis
• How encephalitis is diagnosed and treated by a vet
• How to prevent infectious causes of encephalitis in dogs

Detecting encephalitis in dogs begins with recognizing signs that the brain, spinal cord, or nerves may not be working normally. The key is not just noticing symptoms but understanding that sudden neurologic changes are always serious. Getting the right treatment sooner can improve the outcome for your dog.

If your dog develops sudden neurologic symptoms, such as new or recurring seizures, loss of consciousness, disorientation, head pressing, loss of coordination, or other changes in normal behavior, the best way to help them is to contact your veterinarian or nearest vet emergency clinic as quickly as possible. If you’re unsure if your dog is having an emergency, an online veterinary professional can assist by virtually examining your pet, discussing their symptoms, and offering professional advice on what to do next. However, an in-person veterinary evaluation is necessary for confirming the presence of brain inflammation, identifying potential causes, and providing appropriate treatment.

Encephalitis, also called meningoencephalitis, is a clinical finding of brain inflammation. Finding evidence of encephalitis does not explain why the brain tissue is inflamed, so “encephalitis” is not a full diagnosis. There are many types of encephalitis in dogs with a variety of causes. Encephalitis disorders in dogs include:

• Idiopathic encephalitis
• Steroid-responsive encephalitis
• Granulomatous meningoencephalomyelitis (GME)
• Immune-mediated encephalitis
• Bacterial encephalitis
• Necrotizing encephalitis, or pug dog encephalitis (PDE)

The brain and spinal cord together make up the central nervous system, and inflammation in either part can cause serious neurological problems. Inflammation of the brain (encephalitis) and of both the brain and spinal cord (encephalomyelitis) are some of the most common clinical findings of neurological disease in dogs. Potential causes of encephalitis in dogs include:

• Immune-mediated diseases
• Tick-borne diseases, such as Lyme disease
• Viral infections, such as canine distemper
• Single-cell parasitic diseases, such as toxoplasmosis
• Fungal infections, such as cryptococcosis
• Hereditary disorders, most notably in some small breeds

Most cases of encephalitis in dogs are immune-mediated, meaning the immune system mistakenly attacks the brain. These cases are often classified as idiopathic because no infectious or external cause can be identified. GME and PDE are examples of diseases where the dog’s immune system mistakenly attacks the brain, leading to inflammation. In addition to immune-mediated factors, inherited traits may also contribute to PDE and similar encephalitis cases in small breeds such as pugs, Maltese, Chihuahuas, and Yorkshire terriers. Infectious causes of encephalitis, such as bacterial, viral, parasitic, or fungal diseases, are diagnosed less commonly.

Symptoms of encephalitis can vary depending on the underlying cause, the severity of the inflammation, the area of the brain affected, and how long the disease has been present. Clinical signs may include:

• Lethargy
• Seizures
• Tremors
• Sudden blindness
• Loss of coordination (ataxia)
• Weakness
• Disorientation or confusion
• Signs of pain, especially in the neck and back
• Paralysis
• Behavior changes, such as depression or lack of responsiveness
• Circling
• Head tilt
• Head pressing
• Loss of consciousness

These symptoms are not specific to encephalitis and can develop with many other, more common, health conditions. Regardless of why they’re occurring, the presence of any of these symptoms requires prompt veterinary evaluation.

Seizures and other neurologic symptoms are very common in dogs with encephalitis. Dogs with encephalitis often have sudden, severe symptoms rather than minor or subtle symptoms that get worse over time.

When to seek emergency care

Many symptoms of encephalitis indicate an emergency, such as:

• Seizures
• Sudden blindness
• Loss of coordination
• Sudden paralysis or weakness
• Disorientation
• Head pressing
• Loss of consciousness

These symptoms are considered emergencies and signal a need for immediate, in-person evaluation. Delaying care by researching online or attempting to treat the symptoms at home can lead to a worse outcome and may jeopardize your dog’s health. While online resources may provide background information, emergencies are best addressed through immediate hands-on veterinary care.

Because many different health issues can cause the same symptoms that are associated with encephalitis, diagnostic tests are necessary to identify the underlying cause. Before testing is done, veterinarians usually start with a physical examination and patient history. Pet parents can offer valuable information, such as:

• Timing, frequency, and description of symptoms
• Any recent illness, injury, or tick exposure
• Medications and medical history
• Videos of any episodes or behaviors (when it’s safe to record)

Based on the exam and patient history, recommended diagnostic testing may include:

• More specific examination of the nervous system (e.g., testing reflexes)
• Blood work and infectious disease testing
• Advanced diagnostic imaging, such as CT or MRI scans
• Analysis of cerebrospinal fluid (CSF)

Encephalitis is often idiopathic in dogs, meaning there’s no identifiable cause, even with diagnostic tests. Prognosis for encephalitis in dogs varies widely depending on the underlying cause, how the inflammation responds to treatment, and the severity of the inflammation.

Treatment options for dogs with encephalitis

“Sometimes vets start with treatments that are safe and potentially helpful, even before test results confirm the exact cause,” explains Dr. Jo Myers, a veterinarian on the Vetster platform. “This may involve using safe, supportive treatments that address the most likely or urgent problems, such as seizure control medications and steroids to suppress autoimmune or immune-mediated diseases, while awaiting test results or while monitoring the patient’s response.” For cases with an identifiable cause, treatment involves addressing the underlying disease in addition to relieving inflammation and other symptoms. Treatment options may include:

• Steroids
• Antibiotics, antiparasitics, or antifungal medications
• Chemotherapy/radiation therapy (confirmed tumors only)
• Supportive care for seizures and other symptoms

Because symptoms of encephalitis also occur with many other conditions, treatment without a confirmed diagnosis is not recommended. Veterinary evaluation is necessary to guide safe and effective care.

Most cases of encephalitis cannot be prevented. However, infectious encephalitis can sometimes be prevented with the use of:

• Vaccines to prevent diseases such as canine distemper
• Tick prevention to reduce the risk of tick-transmitted diseases

Hereditary forms of encephalitis are linked to breed predispositions, so responsible breeding practices, such as avoiding breeding dogs with a family history of the condition, may reduce risk.

Symptoms such as seizures, sudden disorientation, head pressing, paralysis, or loss of consciousness are serious warning signs in dogs. These changes always indicate the need for urgent veterinary care, whether or not encephalitis is the underlying cause. It’s more important to ensure your dog receives immediate medical attention than trying to identify the specific cause or guessing at home treatment.

In-person veterinary evaluation is essential for stabilizing a dog in crisis and determining the cause of their symptoms. If you’re unsure if your dog is having an emergency, an online vet can virtually assess your dog’s condition and offer advice on what to do next.

What does encephalitis look like in dogs?

Canine encephalitis, or brain inflammation, causes symptoms that affect the nervous system, such as seizures, lethargy, changes in eyesight, loss of coordination, disorientation, and many other changes. These symptoms also occur in many other much more common illnesses, so getting an accurate diagnosis is necessary for the best chance of successful treatment.

Does my dog with encephalitis need to see a veterinary neurologist?

Veterinary neurologists are specialists who focus on diseases of the brain, spinal cord, and nerves. Not every dog with suspected encephalitis requires referral to a neurologist, but specialists often play an important role when advanced testing, such as MRI or cerebrospinal fluid analysis, is needed, or when a dog doesn’t respond to initial treatment. General-practice veterinarians frequently diagnose and begin treatment for encephalitis, and they determine when a referral is appropriate. Referral may be especially valuable if the case is complex, the cause is unclear, or specialized equipment is needed to guide treatment.

What is the life expectancy of a dog with encephalitis?

The prognosis and life expectancy of a dog with encephalitis depends on the severity of the brain inflammation, the cause of the inflammation, and how long the brain has been affected. Causes of encephalitis vary widely, from bacterial or viral infections to severe autoimmune disorders. It’s important to get an accurate diagnosis from a veterinarian to determine appropriate treatment and your dog’s overall prognosis.

Disclaimer: This article, its content, and its related references do not constitute veterinary advice and should not be considered a substitute for veterinary care. If your pet is showing any symptoms that could indicate a medical emergency, please seek immediate emergency care.