Tick biology and behavior (Proceedings)


Tick biology and behavior (Proceedings)

Apr 01, 2010

Basic tick biology

The common ticks on dogs and cats in North America are all three host ticks. Accordingly, the larvae, nymphs, and adults of each species must each quest, attach to a host, and feed before leaving the host to molt or deposit eggs in the environment. Most of the common ticks of dogs take as long as 2 to 3 years to complete this developmental cycle, becoming dormant and sheltering during adverse environmental conditions and emerging again to actively seek a host when conditions become favorable. One notable exception is Rhipicephalus sanguineus, the brown dog tick or kennel tick, which can survive inside homes and may complete development from egg to egg laying adult in as little as two months. Effective control of ticks and prevention of tick-borne diseases requires (1) recognition of the tick species active in a given area at a particular time of year, (2) understanding of the habitat and reservoir hosts required to support that species, (3) awareness of the reproductive capacity and strategies of ticks, and (4) consistent use of effective acaricide control products on the dog and, when necessary, in the environment.

Identification of common tick species

Although not often pursued, adult ticks can be easily identified by veterinarians and veterinary technicians with minimal effort. Several excellent pictoral keys are available to aid in identification. Knowing the tick species infesting a given dog or active in an area at a particular time of the year enhances our ability to recommend effective control measures, allowing adjustments to be made when necessary. For example, persistent R. sanguineus infestations on a dog suggests a home or kennel infestation may present, whereas A. americanum ticks are more likely acquired from wooded areas around the home where the dog spends its time. Identification of ticks on dogs can also provide valuable information about tick-borne diseases of concern in the area because different ticks transmit different pathogens to dogs.

Rhipicephalus sanguineus

The brown dog tick or kennel tick, Rhipicephalus sanguineus, is the most widely distributed tick on dogs worldwide (Dantas-Torres, 2008), and dogs infested with this tick can be found in every state in the USA although infestations are more commonly reported in the South. Brown dog ticks are unique among the ticks of dogs in that they use dogs as a strongly preferred, almost exclusive host in all life stages. Although individual ticks occasionally feed on another species, such as people or cats, populations of R. sanguineus are supported almost entirely on dogs. In addition, they can tolerate the low humidity inside homes and kennels and can complete their life cycle in as little as 2 months, thus this tick can establish in large numbers and thrive indoors so long as adequate dogs are available for feeding (Dantas-Torres et al., 2006). Home infestations with R. sanguineus, which may be found in climate controlled environments at any time of the year, are particularly troubling because they increase the risk of transmission of zoonotic disease agents, such as R. rickettsii and E. canis (Goddard et al., 1989; Demma et al., 2005). This tick can also thrive outdoors in warmer areas, usually in an area immediately surrounding a home, with peaks of activity occurring late spring to early fall (Goddard 1989; Louly et al., 2007).