New study finds non-endemic tick-borne diseases in UK dogs
9 May 2023
Ticks. We’ve all heard of them and many of us have had the task of removing one from our pet or ourselves. But how much do we know about the diseases they carry?
As National Lyme Disease Awareness Month begins, we take a look at a new paper published in the Journal of Small Animal Practice (JSAP) which reports on the presence of tick-borne diseases in dogs in the UK.1
What’s the story so far?
Whilst only two tick-borne diseases are currently considered endemic in the UK (anaplasmosis and Lyme borreliosis), many more are endemic in continental Europe. With the significant increase in dogs being imported into the UK from eastern Europe in particular, there is a risk of dogs bringing non-endemic tick-borne diseases into the UK and potentially entering the resident tick population, resulting in local transmission and disease in UK dogs.
What tick-borne diseases were found?
In the latest study, 76 dogs with tick-borne diseases were included from seven referral centres, of which 25 were diagnosed with ehrlichiosis, 23 with babesiosis, eight with Lyme borreliosis and six with anaplasmosis1. Fourteen dogs had co-infections with two or three pathogens. Notably, ehrlichiosis and babesiosis are not endemic in the UK, but are endemic in much of continental Europe.
Unsurprisingly, most of the dogs with tick-borne diseases had travelled to or from countries where those diseases are endemic, except for the dogs with anaplasmosis and Lyme borreliosis. However, three dogs with ehrlichiosis, one dog with Babesia canis and one with Babesia vulpes had not travelled outside of the UK, and so presumably became infected from a resident tick in the UK. Significantly, this is the first time Babesia vulpes infection has been identified in a non-travelled dog in the UK. This suggests it is plausible that some canine Babesia species and ehrlichiosis are becoming established in the UK. Canine babesiosis in particular has the potential to become widely established, as its component vectors (Dermacentor reticulatus and a yet uncharacterised Ixodes species tick) are endemic in the UK.
A variety of non-specific clinical signs and laboratory abnormalities were reported in dogs with tick-borne diseases. Overall, prognosis of these dogs was good, with clinical remission achieved in 84% of dogs, thanks to targeted treatment. However, eight dogs were euthanased during hospitalisation (five dogs with ehrlichiosis, two with babesiosis and one dog co-infected with ehrlichiosis, anaplasmosis and leishmaniosis).
What about ticks?
In recent years, there has been a rise in the number of ticks from animals (primarily dogs) which have travelled outside the UK, submitted to Public Health England’s Tick Surveillance Scheme2. The most prevalent tick reported to the scheme was Rhipicephalus sanguineus, the competent vector of Ehrlichlia canis, some Babesia species, Anaplasma platys, Heptazoon canis and Rickettsia conorii.2 Although currently considered non-endemic in the UK, Rhipicephalus sanguineus is increasingly being detected, particularly in southern England3, and climate change may affect the distribution of both non-endemic and endemic ticks, and the diseases they transmit.
What are the recommendations for vets?
It’s recommended that imported dogs are carefully examined for evidence of both tick-borne diseases and ticks themselves. Given that many ticks reported on imported animals are in their nymph or larval forms3, effective acaricidal treatment and environmental control measures to prevent tick persistence should be strongly considered.
This study emphasises the need for veterinary surgeons to consider tick-borne diseases in dogs with compatible clinical presentation and laboratory findings, especially in cases where the dog has travelled. It also highlights the potential for local transmission of non-endemic tick borne-diseases in the UK. Crucially, just because a dog has not travelled, it doesn’t mean tick-borne diseases should be ruled out.
References
1Silvestrini P, Lloyd-Bradley B, Glanemann B, Barker EN, Badham H, Tappin S, et al. (2023) Clinical presentation, diagnostic investigations, treatment protocols and outcomes of dogs diagnosed with tick-borne diseases living in the United Kingdom: 76 cases (2005-2019). Journal of Small Animal Practice. https://doi.org/10.1111/jsap.13592
2Hansford, KM, Pietzsch ME, Cull B, Gillingham EL & Medlock JM (2018) Potential risk posed by the importation of ticks into the UK on animals: records from the Tick Surveillance Scheme. Veterinary Record. 182, 107
3Jameson LJ, Phipps LP & Medlock JM (2010) Surveillance for exotic ticks on companion animals in the UK. Veterinary Record. 166, 202-204