CAPC Recommendations:
Ectoparasites:
Ticks
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.
- Ixodids (hard ticks) are characterized by tick mouthparts that are visible from the dorsal surface and a tick body that is capable of limited expansion. Their environmental stages are found in open areas on vegetation.
- The species of hard ticks listed in these guidelines are three-host ticks, with each motile stage (larva, nymph, and adult) feeding on a different host after molting. The six-legged larval stage hatches from the egg within days to months, depending on environmental conditions. The larva remains on the ground or on low vegetation waiting for a host, which for many species is usually a small rodent or bird. After feeding on the host for a few 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 and final host.
- Argasids (soft ticks) are characterized by a soft and easily expandable body and tick mouthparts that are not visible from the dorsal surface. Their life cycle consists of many nymphal stages; the environmental stages are found in the nests or burrows of hosts.
Stages
- Egg
- Larva
- Nymph
- Adult
Disease
- Ticks may cause anemia as all stages feed on blood and lymph. An adult female can ingest more than 100 times her weight in blood.
- Irritation and pruritus may occur at the site of tick attachment.
- Tick paralysis—an acute, ascending, flaccid, motor paralysis similar to that seen in Guillain-Barre syndrome—is caused by a neurotoxin produced by females of several tick species. The most common offending tick species are D. andersoni, D. variabilis, A. americanum , A. maculatum, I. scapularis, and I. pacificus.
- Disease transmission
- Amblyomma americanum: Ehrlichia chaffeensis (human monocytic ehrlichiosis), E. ewingii, Borrelia lonestari (southern tick-associated rash illness), and Francella tularensis (tularemia)
- Amblyomma maculatum: Hepatozoon americanum (American canine hepatozoonosis)
- Dermacentor variabilis: Cytauxzoon 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)
- Ixodes scapularis (black-legged tick): B. burgdorferi (Lyme disease), Anaplasma phagocytophlium (human granulocytic ehrlichiosis), and Babesia microti (human babesiosis)
- Rhipicephalus sanguineus (brown dog tick): Ehrlichia canis (canine monocytic ehrlichiosis), Babesia canis (canine babesiosis), 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. It appears to be intolerant to cold and persists only in temperate regions within kennels and homes.
Host Associations and Transmission Between Hosts
- Amblyomma americanum
- Larvae and nymphs: bobwhite quail, cats, coyotes, deer, dogs, humans, rabbits, raccoons, red fox, squirrels, turkey, white-tailed deer, wrens, and numerous other mammals
- Adults: cattle, cats, coyotes, dogs, horses, humans, raccoons, 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: bear, birds, bobcats, cattle, coyotes, deer, dogs, goats, horses, humans, pigs, rabbits, and rodents
- Dermacentor variabilis
- Larvae: mice, voles, and numerous small mammals
- Nymphs: cats, dogs, opossums, rabbits, and raccoons
- Adults: cattle, cats, coyotes, dogs, horses, humans, raccoons, and other large mammals
- Dermacentor andersoni
- Larvae: mice, voles, and numerous small mammals
- Nymphs: cats, dogs, opossums, rabbits, and raccoons
- Adults: bears, cattle, coyotes, deer, dogs, horses, humans, 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, cats, chipmunks, humans, mice, opossums, raccoons, shrews, skunks, squirrels, and various rodents
- Adults: bobcats, cattle, coyotes, dogs, foxes, horses, humans, opossums, raccoons, white-tailed deer, and other mammals
- Otobius megnini
- Otobius megnini is a one-host tick with larval and nymph stages as parasites. Adults are not parasitic.
- Larvae and nymphs: bighorn sheep, cattle, cats, coyotes, deer, dogs, goats, horses, humans, mules, rabbits, and sheep
- Rhipicephalus sanguineus
- Larvae, nymphs, and adults prefer to feed on dogs but also feed on other mammals including rodents and rabbits.
- 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 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, three 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 permethrin (available in spray and spot-on formulations).
- Amitraz, fipronil, and permethrin may help prevent tick attachment and cause tick death within 24 to 48 hours. Certain permethrin formulations may also produce repellent-like activity.
- Amitraz, fipronil, and permethrin spot-on formulations can be safely used on dogs, but only fipronil is 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 reinfestation rates. If additional measures are deemed necessary, clients should be informed and notations made in the pet's record before extra-label use of acaricides is recommended. If additional control measures are needed, products may be combined, frequency of application may be increased, 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).
- Having a tick-infested pet does not increase a person’s risk of a tick-transmitted disease. Humans become infected with ticks in the same way as their pets, i.e., by encountering ambushing ticks in tick-infested habitats.
- 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.
- 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 other visiting tick-infested areas. It is especially important that such checks be performed on children.
