Ticks

  • Current Advice on Parasite Control:

    Ectoparasites - Ticks

    Last reviewed and edited Apr 2011

  • Species*

    Canine
    Amblyomma americanum (lone star tick) (Link to Image)
    Amblyomma maculatum (Gulf Coast tick)
    Dermacentor variabilis (American dog tick) (Link to Image)
    Dermacentor andersoni (Rocky Mountain wood tick)
    Ixodes pacificus (western black-legged tick)
    Ixodes scapularis (black-legged tick) (Link to Image)
    Otobius megnini (spinose ear tick) (Link to Image)
    Rhipicephalus sanguineus (brown dog tick) (Link to Image)

    Feline
    Amblyomma americanum (lone star tick) (Link to Image)
    Dermacentor variabilis (American dog tick) (Link to Image)
    Ixodes scapularis (black-legged tick) (Link to Image)
    Otobius megnini (spinose ear tick) (Link to Image)

    *Other tick species may on occasion parasitize dogs and cats

  • Overview of Life Cycle

    • Ticks infesting dogs and cats include the Ixodidae (hard ticks) and the Argasidae (soft ticks); of the species discussed here, only O. megnini is an argasid. The tick species that most commonly infest dogs and cats in North America are the Ixodidae, with O. megnini the exception.
    • Ixodid (hard) ticks are characterized by a highly sclerotinized dorsal shield (a “scutum”) and anterior mouthparts with a basis capitulum that is visible from the dorsal surface. Questing stages of many ixodid ticks that parasitize dogs and cats are found on low vegetation in transitional areas between woods and fields.
      • The species of hard ticks listed in these guidelines are ‘three-host’ ticks, which means that each motile stage (larva, nymph, and adult) will molt off of the host between their requisite blood meals, often feeding on a different host after molting to the subsequent stage. The six-legged larval stage hatches from the egg within weeks to months, depending on environmental conditions. The larva remains on the ground (e.g., in leaf litter) or on low vegetation waiting for a host, which for many species is usually a bird or small mammal. After feeding on the host for several days, the engorged larva drops to the ground and molts to an eight-legged nymph. The nymph then finds an appropriate host and feeds for several days to a week. Once the nymph has engorged, it drops to the ground and molts to the eight-legged adult, which then must find a third host. Ixodid larvae and nymphae will expand and grow several fold in size as they engorge on host blood before they detach to molt. Female adults have a partial dorsal scutum that allows their tegument to expand as they grow as much as 100 times their original weight before they detach from the host. The engorged female will then crawl to a microhabitat with the appropriate relative humidity (such as leaf litter), oviposit (leaving up to several thousand eggs), and then die. Adult ixodid males posses a full scutum that covers their entire dorsal surface, so males do not undergo such a large increase in size and will still appear ‘flat’ when they take a blood meal.
      • Ixodid ticks are further divided into several major groups, or subfamilies, that have different morphology physiology and behavioral biology. These differences can have important effects regarding vector competence and capacity. For example, only members of the genus Ixodes are considered competent vectors of spirochetes that cause Lyme disease. In another group, consisting of the genera Amblyomma, Dermacentor, and Rhipicephalus, adult male ticks must take a blood meal before they are ready to mate. Thus ticks of the latter group copulate as the female feeds on the host, which in turn can result in interhost transfer of the adult ticks as they seek to reproduce. Experimental and ecological data indicate that ixodid males that require a blood meal before mating can persist and even transfer between hosts for some time after feeding, perhaps even through the remainder of the vector season.
    • Argasid (soft) ticks lack a highly sclerotinized scutum and possess mouthparts that originate on the ventral surface. Their life cycle includes multiple nymphal stages; the environmental stages are usually found in association with the bedding, nests or burrows of hosts.
      • Most argasid species spend the majority of their time off the host, living in association with a host bedding area, den or nest, and taking relatively brief (10-60 minutes) blood meals (often at night). Therefore it can be difficult to determine if these argasid species are parasitizing a dog or cat without evidence of pathogens transmitted by such ticks (e.g., relapsing fever spirochetes).
      • The argasid species listed in these guidelines is a ‘one-host’ tick found in the ear canal of its hosts. The spinose ear tick larva crawls into the outer ear of a suitable host where it engorges and molts into a nymph. Nymphs undergo two molts before they leave the host as adults to copulate and oviposit. Unlike most other argasid species, spinose ear ticks do not feed as adults.
  • Stages

    • Egg
    • Larva
    • Nymph
    • Adult
  • Disease

    • Ticks may cause anemia as all stages feed on blood and lymph. An adult female ixodid tick can grow 100-fold in size as she feeds, and ingests more than 100 times her weight in blood (a great deal of these blood meals is defecated by the tick and water from the blood meal is secreted back into the host as tick saliva).
    • Irritation and pruritus may occur at the site of tick attachment.
    • Otoacariasis is the infestation of the ear by ticks or other mites. Some species, such as the spinose ear tick, are specifically adapted to parasitize the auditory canal. Some ixodid species may attach and feed on the pinna that can result in inflammation and discomfort.
    • Tick-borne toxicoses can range from localized inflammation or allergic hypersensitivity to paralysis (associated with ixodid ticks) or severe toxic reactions (usually associated with argasid ticks).
    • Tick paralysis—a form of tick toxicosis characterized by an acute, ascending, flaccid, motor paralysis similar to that seen in Guillain-Barre syndrome in humans—is caused by a neurotoxin produced by females of several tick species. The most common offending tick species in the U.S. are D. andersoni and D. variabilis, but A. maculatum has been associated with tick paralysis in Mexico.
    • Pathogen transmission
      • Amblyomma americanum: Ehrlichia chaffeensis (human monocytic ehrlichiosis), E. ewingii (canine and human granulocytic ehrlichiosis), human southern tick-associated rash illness (etiologic agent undetermined), Francisella tularensis (tularemia), and Cytauxzoon felis (cytauxzoonosis)
      • Amblyomma maculatum: Hepatozoon americanum (American canine hepatozoonosis)
      • Dermacentor variabilis: C. felis (cytauxzoonosis), Rickettsia rickettsii (Rocky Mountain spotted fever), and F. tularensis (tularemia)
      • Dermacentor andersoni: R. rickettsii (Rocky Mountain spotted fever) and F. tularensis (tularemia)
      • Ixodes pacificus (western black-legged tick): Borrelia burgdorferi (Lyme disease) and Anaplasma phagocytophlium (human and canine granulocytic anaplasmosis)
      • Ixodes scapularis (black-legged tick): B. burgdorferi (Lyme disease), Anaplasma phagocytophlium (human and canine granulocytic anaplasmosis), and Babesia microti (human babesiosis)
      • Rhipicephalus sanguineus (brown dog tick): Ehrlichia canis (canine monocytic ehrlichiosis), R. rickettsii (Rocky Mountain spotted fever), Babesia canis (canine babesiosis), Hepatozoon canis (canine hepatozoonosis), and possibly Anaplasma platys and Babesia gibsoni
  • Prevalence

    • Amblyomma americanum is found in the southern plains, Midwest, and eastern United States. Its range extends from central Texas to Florida; north to New York, New Jersey, and Maine; west to Michigan; and south through central Kansas, Oklahoma, and Texas.
    • Amblyomma maculatum is found in the Gulf Coast states, central and eastern Oklahoma, and central and eastern Kansas.
    • Dermacentor variabilis is found in the eastern United States from Florida to southern New England and from the Atlantic coast to the eastern sections of the plains states. Populations also occur along the Pacific coast.
    • Dermacentor andersoni occurs in the Rocky Mountain states from the eastern slopes of the Cascades east to the western edge of the Great Plains and south to New Mexico and Arizona.
    • Ixodes pacificus is found on the Pacific coast and extends into parts of Arizona, Nevada, and Utah.
    • Ixodes scapularis, widely distributed in the eastern and central United States, is found in at least 35 states. The area of distribution is from Maine south to Florida, west into central Texas, and north to Minnesota.
    • Otobius megnini generally is found in drier range areas of the United States particularly the southwest but also occurs in many southern U.S. states.
    • Rhipicephalus sanguineus occurs throughout North America and Hawaii and is very common in the southeastern and West Coast states. This species appears to be intolerant to cold, but persists in temperate regions due to its somewhat unique ability to infest kennels and homes that would be less hospitable for environmental stages other tick species.
  • Host Associations and Transmission Between Hosts

    • Amblyomma americanum
      • Larvae and nymphs: bobwhite quail, turkey, wrens, cats, dogs, coyotes, red fox, pigs, squirrels, rabbits, raccoons, humans, cattle, white-tailed deer, and numerous other mammals
      • Adults: cats, dogs, humans, coyotes, raccoons, horses, cattle, sheep, and white-tailed deer
    • Amblyomma maculatum
      • Larvae: small rodents and ground-dwelling birds such as quail and meadowlarks
      • Nymphs: similar to larval hosts but also includes dogs
      • Adults: birds, humans, dogs, coyotes, bobcats, bear, rabbits, rodents, pigs, horses, cattle, deer, and goats
    • Dermacentor variabilis
      • Larvae: mice, voles, and numerous small mammals
      • Nymphs: cats, dogs, opossums, rabbits, and raccoons
      • Adults: cats, dogs, coyotes, raccoons, horses, cattle, humans, and other large mammals
    • Dermacentor andersoni
      • Larvae: mice, voles, and numerous small mammals
      • Nymphs: cats, dogs, opossums, rabbits, and raccoons
      • Adults: dogs, coyotes, bears, horses, humans, deer, cattle, and sheep
    • Ixodes pacificus
      • Larvae and nymphs: small rodents and birds
      • Adults: large mammals (commonly deer, dogs, coyotes, horses, and humans)
    • Ixodes scapularis
      • Larvae: various rodents such as white-footed mice and shrews; other small mammals; birds and lizards
      • Nymphs: birds, mice, shrews, chipmunks, squirrels, opossums, raccoons, skunks, cats, humans, and various rodents
      • Adults: bobcats, coyotes, dogs, foxes, opossums, raccoons, humans, horses, cattle, white-tailed deer, and other mammals
    • Otobius megnini
      • Otobius megnini is a one-host tick with larval and nymph stages as parasites in the ear of their host. Adults are not parasitic.
      • Larvae and nymphs: bighorn sheep, deer, cattle, sheep, goats, cats, dogs, coyotes, horses, mules, rabbits, and humans
    • Rhipicephalus sanguineus
      • Larvae, nymphs, and adults prefer to feed on dogs but occasionally feed on other mammals including rodents, rabbits, cattle and humans.
    • Most ticks infest dogs and cats by using an ambush technique (questing), although Ixodes spp. may employ both ambush and hunter tactics. Ticks that utilize the ambush strategy climb onto weeds, grasses, bushes, or other leafy vegetation and wait for passing hosts to brush against the vegetation. When stimulated by the presence of a host, they extend their forelegs, which contain a sensory apparatus called Haller's organ. When the host brushes against the plant, the tick immediately releases from the vegetation and crawls onto the host. Ticks that exhibit a hunter strategy run or crawl to attack hosts and are usually associated with animals occupying dens. Most tick species infesting dogs and cats will exhibit host-seeking behavior only during certain periods of the year when climatic conditions favor development and reproduction.
  • Environmental Factors

    • Seasonal tick activity can vary widely by geographic region, and tick populations can vary dramatically within a given area due to local vegetation and host abundance.
      • Amblyomma spp. occur most commonly in woodland habitats with dense underbrush but can also be found in grassy meadows and young forests. The distribution of A. americanum is linked to the distribution and abundance of its primary reproductive host, the white-tailed deer.
      • Dermacentor spp. occur most commonly in grassy meadows and young forests and along roadways and trails.
      • Ixodes scapularis is found in deciduous forests such as maple and oak woodlands and adjacent brush or grass. The distribution of I. scapularis is linked to the distribution and abundance of its primary reproductive host, the white-tailed deer.
      • Otobius megnini is most common in hot, drier range areas, rocky habitats, or animal shelters.
      • Rhipicephalus sanguineus is most common in warm, subtropical climates in shaded sandy areas. Ticks can be found in cracks and crevices in houses, garages, and dog runs. These ticks often crawl up walls in homes and kennels and can be found in false ceilings.
  • Diagnosis

    • Diagnosis is made on physical examination of host, manual removal of tick, and identification (refer to linked images in the Species section). The tick is removed by grasping it as close to the skin as possible with fine forceps or tweezers. The tick is then directly extracted using slow, steady pressure. The tick should not be crushed, twisted, or jerked out of the skin because this may result in exposure to pathogens within the tick or cause the head to become detached and left in the skin, which may lead to infection or granuloma formation.
  • Treatment

    • Ticks can be removed manually (described in the Diagnosis section).
    • Regular application of acaracides is often necessary to protect the dog or cat from ticks and the diseases they transmit.
      • In North America, several topically administered acaracides appear to have the greatest efficacy against ticks: amitraz (available in a spot-on formulation and impregnated collar), fipronil (available in spray and spot-on formulations), and pyrethroids (synthetic pyrethrins) that include deltamethrin (available in spot-on formulation and impregnated collar), flumethrin (impregnated collar), and permethrin (available in spray and spot-on formulations).
      • Amitraz, deltamethrin, fipronil, flumethrin, and permethrin may help prevent tick attachment and cause tick death within 24 to 48 hours. Certain pyrethroid formulations may also produce repellent-like activity.
      • Amitraz, fipronil, deltamethrin, flumethrin, and permethrin formulations can be safely used on dogs, but only fipronil and flumethrin are approved for use on cats.
    • Published data indicate that selamectin kills R. sanguineus and D. variabilis on dogs, but selamectin’s slower speed of kill may not be clinically acceptable in heavy tick infestations.
    • Occasionally label-recommended application of topical acaracides will not appear to control the problem. This failure may be real or perceived, based on pet owner expectations of product performance and re-infestation rates. If additional measures are deemed necessary, clients should be informed and notations made in the pet's record before  additional acaricides are recommended. If additional control measures are needed, products may be combined or an attempt can be made to eliminate ticks in the environment.
  • Control and Prevention

    • Because substantial geographic differences occur in tick prevalence and seasonality, CAPC supports year-round use of topical tick-control products on pets. Furthermore, in certain geographic regions, reactive or seasonal applications of tick-control products may be administered too late to prevent disease transmission.
    • Other tick-control measures include elimination of tick and alternative host habitats by cutting or removing grass, weeds, and brush piles between fences, along property lines, and near buildings. It is also helpful to select plants that do not attract deer.
    • Treating outdoor environments with products such as carbaryl, cyfluthrin, permethrin, or s-fenvalerate can also help in controlling ticks. Acaracides should be allowed to dry before animals or humans are allowed back into the premises.
    • Bait boxes can be used to rid areas of rodents.
    • Acaracides such as cyfluthrin and permethrin can be used in indoor facilities to help eliminate R. sanguineus infestations. Acaricides should be sprayed into cracks and crevices, behind and under cages, and along the boards in the ceiling. It is often preferable to have a licensed pest-management professional (exterminator) apply acaracides on premises indoors and outdoors.
  • Public Health Considerations

    • Many of the ticks that infest dogs and cats will also parasitize humans and can transmit numerous infectious agents (described in Disease section).
    • Humans become infested with ticks in the same way as their pets, i.e., by encountering ambushing ticks in tick-infested habitats. Pets may on occasion bring ticks into the home, which may be mediated with topical tick-control products made for pets.
    • The following measures will aid in preventing human exposure and infestation with ticks.
      • Avoid-tick infested areas, when possible.
      • Wear light-colored clothing when entering infested areas to facilitate visualization of ticks as they crawl on clothing.
      • Tuck pant cuffs into socks to limit access to legs.
      • Walk in the center of trails; avoid vegetation at trail margins.
      • Use a chemical repellent such as DEET, picaridin, or permethrin.
      • Perform daily tick checks when vacationing or visiting tick-infested areas. It is especially important that such checks be performed on children.
      • Take a warm bath or shower (with soap and shampoo) after visiting areas where ticks might be present.
      • If a tick is found on a human host, it can be contained by wrapping it in cellophane tape (engorged females should be killed with alchohol), putting it in a sealable plastic bag, labeling the bag with the date found, and freezing the bag.