Tick-Borne Brain Infections in UK Dogs: What Six Cases From 2021 Show
In 2021, six UK dogs that had never travelled developed brain or spinal cord inflammation linked to a tick-borne virus. Three were put to sleep.
Written by thecanineledger
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If your dog has a fever or seems lethargic and then becomes wobbly, weak, has a seizure or acts strangely, see a vet the same day. A seizure that lasts more than a few minutes is an emergency.
Our note: This advice is ours. The paper describes the signs but gives no owner advice.
→ First Seizure: What to Do, and What Counts as an Emergency
In 2021, six UK dogs developed inflammation of the brain or spinal cord that their vets linked to a tick-borne virus (Gonzalo-Nadal et al., Journal of Small Animal Practice 2024). None had travelled abroad. Three were put to sleep.
While six cases is a tiny number, the authors say they “raise awareness” of these viruses in UK dogs. They could not tell which of two related viruses was involved.
→ Ticks on UK Dogs: What a 12,000-Dog Check Found
1. The study
The dogs. Six dogs seen at three UK referral hospitals in 2021. Three were Labradors. Their median age was 3.5 years. Four lived in Scotland, one in north-east England and one in south-east England.
The viruses. Tick-borne encephalitis virus is found across Europe. Louping ill virus is mainly found in the UK. Both are carried by ticks, and the blood tests used couldn’t tell them apart.
Funding. The authors were funded by UK research councils, the Scottish Government, a medical research charity and others. They declare no conflicts of interest.
2. What happened
Two phases. All the dogs had a fever, lethargy or both at some point, followed by worsening signs of spinal cord or brain disease. These included wobbliness, weakness, seizures and odd behaviour.
Ticks. Three owners had found a tick on their dog within four weeks.
Tick prevention. All the dogs were reported to be on a parasite prevention schedule, though details were missing for one.
Outcome. Three dogs survived but had lasting neurological problems. Three were put to sleep because their signs worsened quickly or didn’t improve.
Our note: All six dogs were reported to be on tick prevention. The paper doesn’t assess whether it failed.
3. What the study can’t tell you
How common it is. Six referral cases can’t show how many UK dogs are affected.
Which virus. The authors say their biggest limitation is that the tests cross-react between the two viruses.
Diagnosis wasn’t always certain. Only one of the three dogs that died had a post-mortem. Test protocols differed between hospitals.
Wording. The abstract says the disease was “caused by a flavivirus”. The title calls it suspected.
Our note: We say “linked to” a virus rather than “caused by”, following the paper’s own caution.
Our note: We leave human health out of this page.
4. What we could not verify
| Commonly said | What we found |
|---|---|
| “Tick-borne encephalitis only affects dogs abroad” | Not here. None of the six dogs had travelled. |
| “Tick prevention means no tick-borne disease” | Not shown. All six were reported to be on prevention, but the study didn’t test whether it worked. |
| “Dogs always recover” | No. Three of six were put to sleep, and survivors had lasting signs. |
Sources
- Gonzalo-Nadal V, Kohl A, Rocchi M, Brennan B, Hughes J, Nichols J, et al. Suspected tick-borne flavivirus meningoencephalomyelitis in dogs from the UK: six cases (2021). J Small Anim Pract 2024: case series, six dogs, three UK referral hospitals. Funded by UK research councils, the Scottish Government and others
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