The Data

THE THEO PROJECT - SECOND DATA REPORT

114 unique cases | 15 countries | May 7th 2026

⚠️ Trigger warning: This report contains data on outcomes including the loss of dogs to MUE. Please read with care.

About this report

The Theo Project launched on April 3rd 2026. Our first data report was published on April 21st, based on 56 submissions from 11 countries. In the five weeks since, our registry has more than doubled. We now have 114 unique submissions from dog owners across 15 countries - Australia, Belgium, Canada, Croatia, Estonia, Finland, Germany, Lithuania, Netherlands, New Zealand, Poland, Singapore, Spain, United Kingdom and USA.

This is our second data snapshot. Like the first, it is crowd-sourced from dog owners and has not been independently verified by veterinary professionals. We are not scientists and we are not drawing clinical conclusions. We are collecting the data that doesn't yet exist and making it available to those who can properly analyse it.

Since publishing our first report, we have begun reaching out to veterinary neurology researchers and research departments to share our data with those who are actively studying this disease. We are hopeful that our data will reach the hands of those who can do something meaningful with it.

Diagnoses represented

Of our 114 unique submissions, dogs were diagnosed with confirmed MUE, confirmed SRMA, GME and related conditions. A number remain suspected but unconfirmed - often due to financial constraints, because the dog deteriorated too rapidly for full testing to be completed, or because the treating vet chose to begin treatment immediately without waiting for confirmatory results.

Outcomes

Approximately 13% of dogs in our registry have sadly passed away from their condition or related complications. Of the remaining dogs, the majority are stable on medication, with a smaller number in full remission and off medication entirely. A significant number are experiencing ongoing flare-ups. These figures remain broadly consistent with published research on MUE, which suggests roughly one third of dogs respond well and achieve remission, one third remain on lifelong medication, and one third do not survive.

Our registry also includes dogs who have lived for many years after diagnosis, with some owners reporting their dogs living five, six, and even eight or more years post-diagnosis.

Age at diagnosis

Dogs in our registry range in age from approximately 10 weeks old to 15 years old at the time of diagnosis. The vast majority were diagnosed under 2 years of age, though our data also includes a number of older dogs.

Area affected

Approximately 40% of dogs in our registry had both their brain and spinal cord affected. Around one in five had brain involvement only, and approximately one in five had spinal involvement only. A smaller number had unknown or unconfirmed areas of involvement.

Breeds represented

While MUE can affect any breed, certain breeds appear repeatedly in our registry. Our registry now includes over 60 distinct breeds. Breeds appearing most frequently include Maltese, Golden Retriever, Chihuahua, Labrador, Pomeranian, Dachshund, Boston Terrier, Whippet, Weimaraner and Miniature Schnauzer. 72% of dogs in our registry came from breeders, a figure that may be relevant in the context of genetic predisposition.

It is important to note that the breed distribution in our registry may be influenced by how The Theo Project has been discovered. The primary way owners have found us so far is through a small number of Facebook groups, one of which is specific to Maltese dogs. This may mean that certain breeds are currently over-represented in our data. It is one of the reasons we hope The Theo Project will continue to spread more widely - the broader and more diverse our reach, the more representative and reliable our breed data will become.

Treatment response

The overwhelming majority of dogs in our registry responded to steroids - primarily prednisone or prednisolone - within days of starting treatment. Additional medications used across submissions included cyclosporine, cytarabine, leflunomide, azathioprine, Keppra and gabapentin among others. Owners noted significant side effects from long-term steroid use including calcinosis cutis, muscle wastage and weight gain, with individual cases of steroid-induced diabetes also reported.

Misdiagnosis

Misdiagnosis before the correct diagnosis was reached was extremely common across our submissions. The most frequent misdiagnoses included intervertebral disc disease (IVDD), Lyme disease, a pulled muscle, ear infection, vestibular disease, and in some cases brain tumour. Several owners describe being sent home by vets multiple times before a neurologist was eventually consulted.

Vaccinations before symptoms

Approximately 51% of dogs in our registry had received vaccinations in the months before symptoms started. This figure has shifted from the 68% recorded in our first report - as our dataset grows and becomes more representative across age groups and countries, these figures will continue to evolve.

Several owners specifically noted a close temporal relationship between vaccination and onset of symptoms, including a number who reported symptoms beginning shortly after routine vaccinations such as booster doses and puppy vaccines.

It is important to note that the majority of dogs receive vaccinations routinely, which means this figure alone cannot establish causation. The Theo Project remains neutral on vaccination - we recognise it is a vital and important part of protecting dog health for most dogs. We are simply collecting and reporting what owners have shared with us, so that researchers can investigate patterns that owners are observing in the real world. We are not drawing conclusions - we are asking questions. If the data ultimately shows no meaningful relationship, that is a valuable finding too.

Flea and tick treatment before symptoms

Approximately 62% of dogs in our registry had received flea and tick treatment before symptoms started. The most commonly named products were Simparica Trio, Nexgard, Bravecto and Revolution - many of which belong to the isoxazoline class of drugs, which carry an existing FDA warning regarding neurological side effects in some dogs.

Several owners noted a specific temporal relationship between flea and tick treatment and onset or relapse of symptoms, with a number independently flagging isoxazoline products as a potential concern.

As with vaccinations, the majority of dogs receive flea and tick treatment routinely, so this figure alone cannot establish causation. The Theo Project remains neutral on flea and tick prevention - we recognise it plays an important role in protecting dog health. We are simply recording what owners have reported so that researchers can investigate further. We are not making claims. We are collecting data - and we believe that data, whatever it ultimately shows, belongs in the hands of people who can properly analyse it.

Litter connections - a notable finding

One of the most striking patterns to emerge since our first report is the number of cases where multiple dogs from the same litter were independently diagnosed with MUE or SRMA. These cases were not solicited - owners volunteered this information independently.

In one case, 3 of 9 puppies from the same Golden Retriever litter in Lithuania were diagnosed with SRMA at different ages - 4 months, 8 months and 10 months respectively, with the attending neurologist suspecting genetic predisposition. A Bernese Mountain Dog owner reports 4 dogs from the same litter were all diagnosed within days of each other. A Welsh Springer Spaniel owner notes that this is the second dog in their family to be diagnosed - the first was a half-sibling with the same father, diagnosed with GME, who lived to 12. A Whippet breeder reports that two of her dog's sisters were also diagnosed - one with SRMA, one with MUO.

These cases raise important questions about genetic predisposition that we hope researchers will investigate. Whether certain breeding lines carry a higher risk of immune-mediated neurological conditions is a question our registry is uniquely positioned to help explore.

The financial impact

The financial impact of MUE is a theme that runs through almost every submission in our registry. Owners describe spending thousands - and in some cases tens of thousands - of pounds, dollars and euros on diagnosis and treatment. Many describe using savings, credit cards and crowdfunding platforms. Several describe stopping chemotherapy because they could no longer afford it. Insurance frequently did not cover the full cost.

A note on our submission form

Since launching, we have added two new questions to our registry form: whether your dog has ever had a poor reaction to a vaccine, and whether you are submitting for the first time or resubmitting to update a previous entry. If you submitted your dog's story earlier and would like to add or correct any information, you can now do so by resubmitting the form and selecting "resubmitting to update a previous entry." We will match it to your original submission and update your record manually. Every update helps.

What this data cannot yet tell us

Our registry is five weeks old and 114 cases strong. This is a growing foundation, not a conclusion. The patterns we are observing - particularly around litter connections, vaccinations, flea and tick treatments, breed predisposition and outcomes - are compelling, but they require a much larger dataset to be statistically meaningful. We are not scientists and we are not drawing clinical conclusions. We are collecting the data that doesn't yet exist and making it available to those who can.

What happens next

We will continue to publish updated data reports as the registry grows. We are in the process of sharing our data with veterinary neurology researchers who are actively studying this disease. Every submission brings us one step closer to turning the unknown into the known.

If you haven't yet submitted your dog's story - please do.

A note on our data: This data is crowd-sourced from dog owners and has not been independently verified by veterinary professionals. It is intended as a starting point for understanding - not as medical advice. As our registry grows, so will the reliability and depth of what we can share.

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Our first data report, published April 21st 2026 and based on our initial 56 submissions, is available to view here.