Photo of a woman (Emma Thilén, SLU) sitting outdoors with a spaniel-type dog.
Emma Thilén is pursuing a PhD at SLU during the period 2024-2029 within the project “Virus-induced encephalitis in dogs and humans - causes and disease patterns in Swedish populations.” Photo: Lisa Chröisty, SLU

Virus-induced encephalitis in dogs and humans – in search of answers to the questions of why

Page reviewed:  19/09/2025

The brain is one of the body's most important and most fragile organs, for both dogs and humans. If the central nervous system becomes infected, it can be fatal. What do we know about the viruses that can cause this? And can similarities between species be demonstrated? That is now the question.

Tiny slices of inflamed brain tissue lie on the microscope slide. The light comes on. The focus is adjusted. And suddenly, there it is, right before your eyes: the inflamed structure of brain tissue. ready to be explored by the research team seeking the answer to the question “why?”

Every year, both dogs and humans suffer from viral encephalitis, which can affect the entire central nervous system (CNS). The disease is often serious, and knowledge about it is very limited.

So, what causes these cases of disease? And how does the damage to the brain occur? These are important questions that are still waiting to be answered.

When it comes to dogs, in most cases it is actually impossible to find the underlying cause of encephalitis, explains Emma Thilén, veterinarian and doctoral student in the project, and continues: And the same is true for humans. Why is that? Well, perhaps because there are viruses that have not yet been discovered.

To search for something yet unknown

Dogs suffering from inflammation of the central nervous system are often brought to the vet with symptoms such as movement disorders, seizures, behavioral changes, and/or fever. Some treatment is available, but at present it can be difficult to make a reliable clinical diagnosis.

That is why this research project has now been launched, with a broad objective. It involves expanding knowledge about the cause of brain inflammation in dogs and making comparisons between dogs and humans in the hope of finding common disease patterns.

The aim is to pave the way for a future with better knowledge and diagnostic methods, and where it is possible to prevent the disease from occurring in the first place.

So what I'm going to do now is analyze for viruses that are known, but also for those that are still unknown, says doctoral student Emma Thilén.

In the project, she and the research team will analyze brain specimens from deceased dogs and humans who suffered from inflammation of the central nervous system.

This is all thanks to an archive of tissue samples saved over many years—and highly advanced technology.

In the service of dogs and humans

It is easy to relate to the concern that arises when a loved one falls ill, regardless of whether it is a dog or a human being. The dream scenario, which doctoral student Emma Thilén has set as her long-term goal, is therefore to work towards a future where the disease can not only be cured, but also prevented.

If my research can contribute to improved diagnostics in the long term, the hope is that it will lead to better conditions for both treatment and preventive measures. That would feel very valuable, she says.

Towards a future where questions are answered

The project is therefore already in full swing in the fall of 2024. In brief, the coming period will involve:

  • Map the incidence of encephalitis in the Swedish dog population over the past 25 years and investigate the types of changes that occur in brain tissue.

  • Search for both known and previously unknown viruses as causes of encephalitis in dogs.

  • Use medical records and collected data to increase understanding of the characteristics that distinguish dogs that are affected by encephalitis from those that are not.

Next, it will be time for the joint approach to dogs and humans, where the research team hopes to identify potential risk factors for brain inflammation and see patterns that can be transferred from humans to dogs and dogs to humans.

If we find common disease patterns between dogs and humans, this may also point to a common underlying cause, says doctoral student Emma Thilén.
Photo of a woman (Emma Thilén, SLU) sitting at a microscope in a laboratory.
“My dream scenario would be to know enough about brain inflammation to be able to prevent it to such an extent that it never actually occurs at all,” concludes the doctoral student. Photo: Lisa Chröisty, SLU

Facts:

  • The project and doctoral position is funded by Agria and SKK's research fund, the Birgitta Carlsson Fund, Animal Protection Stockholm, and the Ingeborg Ögren Fund, and is expected to run from spring 2024 to 2029.
  • One of five doctoral projects at SLU focusing on diseases common to dogs and humans.
  • The doctoral student in the project is Emma Thilén, together with a research group consisting of:
    • Cecilia Ley, principal supervisor and researcher in veterinary pathology at the Swedish University of Agricultural Sciences, SLU
    • Mikael Berg, supervisor and professor of veterinary virology at SLU
    • Nils Fall, supervisor and professor of clinical veterinary epidemiology at SLU
    • Sylwia Libard, project supervisor and senior physician in pathology at Uppsala University
    • Karolina Engdahl, researcher in small animal epidemiology at SLU
    • Erika Karlstam, laboratorieveterinär och patolog vid SVA
    • Dennis Rubbenstroth, Head of Laboratory at the Friedrich Loeffler Institute
    • Kaspar Matiasek, Professor of Diagnostics and Neuropathology at Ludwig Maximilian University

The project is divided into three sub-studies, all of which build on each other – broadly described as:

  1. In the first part, the research team will examine brain specimens from dogs—stored in an archive dating back to the 1970s—and examine tissue from the last 25 years. The goal is to characterize the subgroups of inflammation with questions such as "What type of inflammation is it, and in which parts is it visible? Based on previous medical records and insurance data, information about the affected dogs will also be collected, based on aspects such as gender, breed, where in the country they lived, any stays abroad, etc., in order to search for potential links between the onset of the disease and lifestyle factors.

     

  2. In part two, analyses of known and unknown viruses will be carried out using advanced technology, including next-generation sequencing/high-throughput sequencing, bioinformatics, RT-qPCR, immunohistochemistry, and in situ hybridization (RNA-scope).

     

  3. In part three of the project, the dog-human perspective will be taken into account. As in parts 1 and 2, preparations from affected human brains will now be examined and living conditions mapped. The findings will ultimately be compared with those in dogs to identify any common causal relationships and risk factors that could provide new knowledge about the onset of encephalitis.

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