Pug Dog Encephalitis: Causes, Symptoms & Hereditary Testing

Pug puppies are among the UK’s most beloved small dog breeds, known for their distinctive looks and charming character. Unfortunately, pugs have a predisposition to several hereditary health problems, one of the most serious being pug dog encephalitis (PDE).

PDE is a unique, immune-mediated neurological disease primarily affecting pugs. It causes inflammation and necrosis (death) of brain tissue and its protective coverings, leading to severe neurological symptoms and, ultimately, death. This condition severely affects a pug’s quality of life and lifespan.

Understanding Pug Dog Encephalitis

Pug dog encephalitis generally manifests in dogs from about 6 months to 7 years old, with most cases occurring between 1.5 and 3 years of age. Symptoms can develop suddenly or gradually and vary widely in progression speed—some dogs deteriorate rapidly within weeks, while others may show slower decline over months.[1]

Common signs include:

• Seizures, often severe and difficult to control
• Pressing the head against walls or objects to relieve skull pressure
• Atypical behaviours such as circling, staggering, or walking in circles
• Visual impairments or apparent blindness
• Lethargy, depression, or behavioural changes including confusion and disorientation
• Weakness, unsteady gait, or stumbling

These symptoms reflect the brain inflammation and damage caused by an abnormal immune response where the dog's immune system attacks its own brain tissue rather than an infectious cause.[2][3]

Who is At Risk?

Since PDE is hereditary, all purebred pugs are at potential risk unless genetically tested clear. Crossbred dogs with pug ancestry have a lower risk due to hybrid vigour but are not completely immune. Female pugs, particularly of the common fawn colour, may be somewhat more likely to develop the condition.

Data estimates PDE accounts for around 1% of deaths in UK pugs, but many more may be carriers of PDE-associated genes.[4]

Genetics and Hereditary Inheritance

PDE inheritance follows an autosomal recessive pattern. This means a dog must inherit two copies of a mutated gene (one from each parent) to be affected. Dogs can also be carriers (one mutated gene) without showing symptoms but can pass the gene to offspring.

Dogs are classified into three genetic statuses:

• Clear (no PDE gene present)
• Carrier (one copy of the PDE gene)
• Affected (two copies of the PDE gene causing disease)

Breeding pairs’ statuses predict litter outcomes as follows:

• Two clears will produce only clear puppies.
• Two affected parents produce only affected puppies.
• Two carriers produce a mixed litter (approx. 25% affected, 50% carriers, 25% clear).
• Clear and carrier parents produce 50% clear and 50% carrier puppies.
• Clear and affected parents produce all carrier puppies.
• Carrier and affected parents produce 50% carriers and 50% affected puppies.

How to Get Your Pug Tested

Genetic testing for PDE can be done through a simple DNA sampling (often a buccal swab) collected by your vet. Samples are sent to The Kennel Club’s approved laboratories in the UK for analysis. Results inform breeders and owners on the status to make responsible breeding and health decisions to reduce PDE prevalence.

Diagnosis, Management and Prognosis

Currently, there is no definitive test to diagnose PDE in a living dog, though magnetic resonance imaging (MRI) and cerebrospinal fluid analysis can support suspicion. Confirmation usually requires post-mortem brain examination.

There is no cure for PDE. Treatment focuses on managing symptoms, primarily seizures, with anticonvulsant and immunosuppressive medications to improve quality of life temporarily. Unfortunately, the disease is progressive and fatal, often resulting in death within months of onset.[2][3]

Ongoing research seeks better early detection methods, including imaging and genetic marker studies. Responsible breeding guided by genetic testing remains the best tool to reduce PDE incidence and improve pug health in the future.

Summary

Pug dog encephalitis is a devastating hereditary immune-mediated brain disease unique to pugs. Early genetic testing and informed breeding decisions offer the best prospects for reducing the impact of this fatal condition. If you own or are considering a pug, understanding PDE is essential to responsible ownership and supporting this lovely breed’s wellbeing.