Dr. Rebecca Windsor gives an update on the clinical trials to improve outcome for Necrotizing Meningoencephalitis in Pug Dogs (aka Pug Dog Encephalitis)

Bark n Wag 15 Minute Vet Talk

• Pug encephalitis causes inflammation of the brain in some small-breed dogs.
• It is always fatal and there is no cure.
• It is estimated that 1.2 percent of Pugs will die from this condition.
• It is believed to be an inherited autoimmune disorder with genetic markers.
• Vets may prescribe steroids or other immunosuppressive drugs to manage the condition.

Pug dog encephalitis (PDE) is a severe and debilitating disease in small breed dogs that causes inflammation of the brain. This condition is inherited in Pugs but can occur in other breeds as well.

Unfortunately, the disease is fatal and it is estimated that 1.2 percent of Pugs will die from Pug encephalitis (1). Although there is no cure for this disease, early diagnosis and management can help your dog maintain a good quality of life for as long as possible.

What is Pug Dog Encephalitis?

Pug dog encephalitis is the colloquial name for Necrotizing Meningoencephalitis (NME), a severe and incurable condition that causes inflammation and death of the brain tissue.

Although the disease primarily affects Pugs, other small breed dogs—including Maltese, Chihuahuas, and Yorkshire Terriers, can be affected as well.

Young adults are most commonly affected, with most being diagnosed before 7 years of age. Young, fawn-colored, female Pugs are especially prone to developing this condition.

What Causes the Condition?

Pug encephalitis is believed to be an inherited autoimmune disorder. In Pugs, genetic markers have been identified that can predict a dog’s risk for developing the disease. One in eight Pugs with two copies of these genetic markers will develop Pug encephalitis in their lifetime (2). At this time, it is not known why some dogs develop the disease while others do not.

Other small breeds such as Maltese, Chihuahuas, and Yorkshire Terriers can also develop NME. A genetic basis is suspected in these breeds as well, but has not yet been proven. To date, the disease has not been reported in medium or large breed dogs.

Symptoms of Pug Dog Encephalitis

The symptoms of Pug dog encephalitis may come on gradually or may progress rapidly depending on the patient. Many cases start with vague symptoms such as lethargy and depression, which can often be overlooked.

As the disease progresses, pet owners may notice more dramatic symptoms, such as:

• Seizures
• Collapse
• Circling
• Appearing lost or disoriented
• Behavior changes
• Weakness, stumbling
• Blindness
• Abnormal gait
• Coma

Diagnosing the Condition

If your dog is showing symptoms of Pug encephalitis, you should seek veterinary care immediately. Other conditions may present with similar symptoms, so your veterinarian will likely recommend several diagnostic tests to determine the underlying cause of your dog’s clinical signs.

Sampling the brain tissue through biopsy or necropsy is the only way to definitively diagnose Necrotizing Meningoencephalitis. However, other less invasive tests may be used to establish a tentative diagnosis.

Your veterinarian will perform a full physical examination, and may perform some or all of the following tests:

Blood Work. A complete blood count and biochemistry panel may be performed to evaluate organ function and look for underlying conditions such as liver disease or toxin exposure, which can cause similar clinical signs.

Diagnostic Imaging. Imaging such as MRI may be used to evaluate your dog’s brain and spinal cord. Often this requires referral to a specialist. Your dog will also likely need to be placed under general anesthesia for this procedure.

CSF Tap. Your veterinarian may recommend taking a sample of your dog’s cerebrospinal fluid (CSF), which surrounds the brain and spinal cord. Examining the cells of this fluid under a microscope can help rule out other types of meningitis and encephalitis that cause similar clinical signs.

Genetic Testing. In Pugs, a genetic test is available that can identify which individuals are at higher risk for developing NME. Dogs with two copies of the genetic markers of NME are 12.75 times more likely to develop the disease in their lifetime, compared to dogs with only one or no copies of these markers (2).

How to Treat Pug Encephalitis

Unfortunately, there is no cure for Pug encephalitis. Treatment is focused on decreasing the immune response, alleviating inflammation, and minimizing seizures.

Your veterinarian may prescribe steroids or other immunosuppressive drugs to manage the condition. Antiepileptic drugs may also be prescribed for patients experiencing seizures due to NME. Most patients will need to stay on these medications for life and will relapse if the medication is discontinued. Because these medications can have severe side effects, some trial and error may be necessary to find the drugs and dosages that work best for your dog.

Pug Dog Encephalitis Life Expectancy

Pug dog encephalitis is a serious condition and is ultimately fatal. Most dogs will succumb to the disease within a year of diagnosis, although some dogs can survive for several years with medication and supportive care.

Frequent rechecks with your veterinarian will be necessary to monitor response to treatment and ensure your dog is maintaining a good quality of life.

Cost to Manage Pug Encephalitis

Pug encephalitis can be costly because it often requires advanced testing to diagnose the condition. In some cases, your dog may need to be referred to a specialist for diagnosis and treatment.

Depending on the medications used, your dog may also need frequent rechecks and blood work to monitor the effects of these drugs.Thus, pet owners should expect to spend several thousand dollars on diagnosis and treatment of Pug dog encephalitis.

How to Prevent Pug Dog Encephalitis

Studies have shown a strong familial inheritance of this disease in Pugs. The disease is also believed to be genetic in other breeds, although this has not yet been proven. Any dog diagnosed with Pug encephalitis should not be bred, because there is a high risk that the disease will be passed on to the dog’s offspring. The parents of affected dogs should also not be bred together again, as they may be carriers of the disease.

In Pugs, a genetic test is available which can help identify potential carriers of Pug dog encephalitis. Testing before breeding is recommended to avoid producing puppies with a higher risk of developing this disease.