Ticks from cats in the United States: patterns of infestation and infection with pathogens

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Tick infestations were documented on 332 cats from 18 states in the United States.

Adult and immature stages of IxodesAmblyomma, and Dermacentor were recovered.

Molecular assays documented infection with at least one pathogen in 17.1% of ticks.

One in 5 cats with ticks spent ≤30% time outdoors; 10 were reportedly indoor only.

Results show cats at risk of tick infestation and exposure to tick-borne pathogens.


Ticks are an important but under recognized parasitic threat to cats in many areas of the United States. To characterize the species and stages of ticks most commonly recovered from cats and determine the prevalence of disease agents in the ticks, we conducted a survey of ticks removed from cats at veterinary practices in 18 states from April 2016 – June 2017.

A total of 796 ticks were submitted from 332 cats from 41 different veterinary practices. A single tick was submitted from the majority of cats, with a mean infestation intensity of 2.4 (range 1–46). The most common tick was Ixodes scapularis, accounting for 422/796 (53.0%) ticks submitted, followed by Amblyomma americanum (224/796; 28.1%) and Dermacentor variabilis (131/796; 16.5%); a few I. pacificusI. banksiD. occidentalisA. maculatumRhipicephalus sanguineus, and Otobius megnini were also submitted.

A majority of ticks were adults (593/796; 74.5%); females predominated in all adult tick submissions including I. scapularis (277/327; 84.7% female), A. americanum(66/128; 51.6% female), and D. variabilis (75/126; 59.5% female). Immature ticks included 186 nymphs and 17 larvae and were primarily I. scapularis and A. americanum.

Adult I. scapularis were most reported to be attached to the dorsal head and neck; A. americanum to the abdomen and perianal region; and D. variabilis to the back and ear. Ticks were collected in every month; the largest number of submissions were in May and June (42.5% of ticks) and October and November (35.9% of ticks). Adults of I. scapularis were most commonly submitted October through DecemberA. americanum March through June, and D. variabilis May through July.

Cats with ticks were predominantly male (58.8%) and altered (76.2%), and most reportedly spent >30% of time outdoors, although 64/294 (21.8%) for which lifestyle estimates were provided were reported to live primarily (≤30% of time outside; n = 54) or entirely (100%; n = 10) indoors.

Assay of ticks removed from cats revealed I. scapularis were infected with Borrelia burgdorferi (25.7%) and Anaplasma phagocytophilum(4.4%); A. americanum were infected with Ehrlichia chaffeensis (1.3%); and D. variabilis were infected with spotted fever group Rickettsia spp. (3.1%). No ticks in this study tested positive for Cytauxzoon felis.

Pet cats, including those that live primarily indoors, are at risk of tick infestation, potentially exposed to tick-borne disease agents, and would benefit from routine tick control.



Some interesting points:

  1. Ticks were found on cats year-round
  2. The majority of ticks were ADULTS
  3. This study points out we need to essentially throw out the idea you can only get a tick bite in the spring and fall.  It also points out that adult ticks are to be taken just as seriously as nymphs.
  4. According to the study, molecular assays were used and the following pathogens found.  It says nothing of Bartonella, which is unfortunate.  We really need to determine why so many humans are infected with it.

Table 4. Pathogens detected in adult ticks recovered from cats.

Tick Pathogen % positive (No. positive/No. tested)
Ixodes scapularis Anaplasma phagocytophilum 4.4% (12/272)
Borrelia burgdorferi 25.7% (70/272)
Amblyomma americanum Cytauxzoon felis 0% (0/121)
Ehrlichia chaffeensis 1.7% (2/121)
Ehrlichia ewingii 0% (0/121)
Dermacentor variabilis Cytauxzoon felis 0% (0/123)
Rickettsia spp. 3.1% (4/123)