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Be tick aware: when and where to check cats and dogs for ticks
  1. Ian Wright1,
  2. Benjamin Cull2,
  3. Emma L Gillingham2,
  4. Kayleigh M Hansford2 and
  5. Jolyon Medlock2
  1. 1 The Mount Veterinary Practice, Fleetwood, UK
  2. 2 Department of Medical Entomology and Zoonoses Ecology, Public Health England, Porton Down, UK
  1. E-mail for correspondence; hammondia{at}hotmail.com

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Tickborne disease represents a long established risk to human and pet populations. Increasing pet travel and importation is occurring concurrently with an expanding distribution of tick vectors and tickborne diseases, bringing new challenges for veterinarians. In the UK, the most common tick species, Ixodes ricinus, bites humans and companion animals, and can put both groups at risk of endemic diseases such as Lyme disease.1–5 The prevalence of Lyme disease-causing Borrelia in ticks removed from dogs and cats in the UK is low, approximately 2 per cent.1 4 5 Recent large-scale incidence data for Lyme disease in cats and dogs are lacking but the presence of causative agents in ticks attached to cats and dogs demonstrates that they are being exposed to infection. The wide range of non-pathognomonic ways in which Lyme disease can present also means it is likely to be underdiagnosed. Dogs and cats may also act as transport hosts for infected ticks, moving them into new locations. Other tickborne diseases may also pose a risk. For example, Babesia canis has recently been reported for the first time in the UK6 and increasing numbers of Rhipicephalus sanguineus ticks are being found on recently travelled or imported dogs.7 These threats make tick surveillance and accurate tick prevention advice for people and their companion animals vital for both human and animal health.

Veterinary professionals should recommend licensed tick preventive products that rapidly kill or repel ticks for pets whose lifestyle puts them at increased risk of tick exposure or for pets travelling abroad (ESCCAP UK & Ireland). In addition, owners should check themselves and their pets regularly and safely remove any ticks found. Guidance on safe tick removal can be found on Public Health England’s (PHE) tick surveillance pages (www.gov.uk/guidance/tick-surveillance-scheme). Although there may be some risk of reaction at tick bite sites if ticks are removed incorrectly, to the author’s knowledge, there are no large studies demonstrating quantifying the incidence of this occurring and these effects can be mitigated by educating pet owners how to remove ticks correctly. Ticks can be hard to detect on pets if immature stages are present or if long or densely coated animals are being examined.8 Reliable data on the bite site location of ticks on pets, therefore, would aid veterinary professionals and parasite advice groups to better guide clients as to where to look for ticks on their animals. Coupled with knowledge of peak pet-tick exposure periods, this could increase detection of feeding ticks, potentially reducing the risk of tickborne disease transmission, and may also encourage pet owners to think about their own health by making them tick aware.

Here, we describe the bite site locations of ticks acquired by cats and dogs within the UK during 2016, which were submitted to PHE’s Tick Surveillance Scheme (TSS) for identification. As part of standard TSS data collection, the location on the body where the tick(s) was found feeding was recorded when available.

During 2016, up to 630 records were received from dogs and cats; 393 (62.4 per cent) records were submitted by vets and 237 (37.6 per cent) by members of the public. Of the 481 records from dogs, 79.4 per cent were I ricinus, 18.9 per cent I hexagonus and 1.7 per cent other species (Dermacentor reticulatus, Haemaphysalis punctata and I canisuga). Of the 149 records from cats, 51.7 per cent were I ricinus, 46.3 per cent I hexagonus and 2.0 per cent other species (I canisuga and I ventalloi). These results were comparable to other recent studies identifying ticks found on dogs and cats.2 5

Ticks were collected from both hosts throughout the year. On dogs, I ricinus was found mainly during April to September, with highest numbers removed from May to July (Fig 1). I hexagonus was mainly found between May and July. The seasonality of I ricinus on cats was similar, being removed primarily during April to September, but with peak records received from April to June (Fig 1). Cats were infested with I hexagonus year-round, with submissions frequently received from April to December. I ricinus collected from dogs constituted 17.2 per cent adult males and 82.8 per cent adult females, and from cats 11.0 per cent males, 87.6 per cent females, 1.3 per cent nymphs and 0.2 per cent larvae. In contrast, I hexagonus from dogs was 51.0 per cent nymphs, 35.9 per cent females and 13.1 per cent larvae, and from cats 52.7 per cent nymphs, 39.0 per cent females, 6.8 per cent larvae and 1.4 per cent males.

FIG 1:

The seasonality of Ixodes ricinus (blue) and I hexagonus (red) removal from cats (solid lines) and dogs (dashed lines).

Information on bite site location was included in 62.8 per cent records from dogs and 61.7 per cent records from cats. On dogs, ticks were most frequently removed from the head (49 per cent), legs (12 per cent), neck (9 per cent) and chest (8 per cent; Fig 2). Of the ticks removed from the head, the majority were located around the eyes (25 per cent), ears (24 per cent) and muzzle (15 per cent; Fig 2). Similarly, on cats, ticks were most frequently removed from the head (43 per cent), neck (32 per cent) and legs (6 per cent; Fig 2). Ticks recorded from cats’ heads were frequently removed from around the ears (30 per cent), under the chin (20 per cent) and on the face and muzzle (9 per cent each; Fig 2).

FIG 2:

Tick bite locations on dogs and cats.

Twenty-three records involved ticks (all I ricinus) found in pet owners’ houses, and were collected from the floor (n=10; 43.5 per cent), pets’ bedding (n=7; 30.4 per cent) and furniture (n=6; 26.1 per cent). Eight of these records were associated with cats and the remaining 15 associated with dogs. All records, except one which consisted of four females, involved single adult ticks (three males, 23 females). The majority of ticks found in houses were engorged females (n=19; 73.1 per cent), likely detached from their hosts after feeding ready to lay eggs. Four unengorged females were also recorded; three of these fell off cats, likely due to recent acaricide treatment, and one was scratched off by a dog. The remaining three ticks were males.

The role of veterinary professionals and parasite advice groups is fundamental in giving accurate evidence-based advice to pet owners regarding ticks and tickborne disease prevention. This improves pet health and also has the potential to reduce human tickborne disease exposure by raising the awareness of what ticks look like, where and when they can be found and which animal or human health risks are associated with them. Successfully finding ticks on pets is important to reduce the potential risk of pathogen transmission and because the presence of ticks on dogs suggests that owners would also have visited areas similar to their pets and may have been exposed. If owners find ticks on their pet, they may also be more likely to check themselves and take more personal tick preventive precautions.

Data from the current study and others9-11 suggest that owners can improve their chances of detecting ticks on their pets by concentrating searches on the head, neck and legs. It is possible that results are biased towards those areas of the pets that are easily accessible to their owners and vets; however, our data match those of systematic studies involving vets and owners closely examining animals for ticks.9 10 Although tick bite risk for pets appears to be highest during April to September, it is important to remain vigilant all year, particularly in areas of the UK where D reticulatus is present and active during the winter months,12 and when animals have recently travelled. The year-round risk of tick bites on cats and dogs has also been highlighted by other recent UK surveillance.13

Performing regular tick checks on pets could reduce the risk of companion animals acquiring a tickborne infection. In addition, appropriate tick treatments could be used. If pet owners learn to recognise the most common tick species in the UK (I ricinus), spotting unusual ticks that may present more serious or less well-known tickborne disease risks should become easier. This is particularly relevant in assessing the risk posed by ticks found within the house which may be native I ricinus carried inside by pets, or represent a more serious threat of house infestation by imported R sanguineus.14

Veterinarians should pass this information onto pet owners and encourage them to submit any ticks they find, particularly those they consider to be unusual, to PHE’s TSS so that up-to-date knowledge of the distribution of tick vectors can be maintained.

References

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Footnotes

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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