New information sheds more awareness on canine ehrlichiosis - DVM
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New information sheds more awareness on canine ehrlichiosis

DVM Best Practices

The likelihood of disease transmission is dependent upon the abundance of appropriate tick vectors and infected mammalian hosts in the same geographic region. The species of ticks involved in the transmission of ehrlichia organisms to dogs include Amblyomma, Ixodes and Rhipicephalus (Photo 4). The three-life stages of these ticks feed on separate hosts.

Prevention Ehrlichia vaccines for dogs are not available but may be in the near future. Continuous low-dose tetracycline has been reported to be successful in the prevention of E. canis infection in an endemic area of Africa. The incidence of disease in treated dogs in this study was less than 1 percent. This is not a practical or wise treatment regime because of the potential selection of resistant strains of bacteria.

As simple as it may sound, avoidance of tick-infested areas during peak tick questing seasons is a highly effective strategy. Clients should realize that walking their dogs through tall grassy or wooded areas in the spring and the fall might lead to multiple tick infestations. Keeping lawns and brush mowed in and around the dog's yard will reduce tick numbers.

If exposure to questing ticks cannot be avoided, their prompt removal from the animal before attachment will benefit the animal. Ticks that have started the attachment process should be grasped with fine forceps, pulled straight out and placed into 70 percent alcohol. No twisting, heat, nail polish or other household compound has proven to be useful in tick removal. Once the tick is removed, disinfection of the attachment site is recommended. Some ticks will survive the flush of a toilet. Clients should be reminded of the rare, but possible, disease transmission hazard of crushing engorged ticks. Repellants containing DEET are effective for adult clients but should never be used on children, cats or dogs. Environmental control of ticks is challenging even for professional pest control operators (PCOs). Identification of the tick species involved will help direct the prevention effort. Rhipicepalus spp. infestations in kennels are very difficult to control because all life stages will feed on dogs. Rodent control will help, but will not eliminate the infestation. Most attempts to eliminate deer from backyards are relatively futile.

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Tick control can usually be accomplished with the regular topical application of residual insecticides such as amitraz, fipronil and permethrin. Duration of activity varies considerably based upon formulation, dog activity, and acaricide tolerance or resistance in a given region. All permethrin products must never be used on cats and only with extreme caution on dogs that interact with cats.

Conclusion Veterinarians play a major role in the prevention, diagnosis and treatment of ehrlichia infections in dogs. There is a very fine line for creating awareness of tick-borne diseases without generating panic and concern in the pet-owning public. Even though the zoonotic role of dogs as a reservoir for human infection has never been shown to be a threat, it is still a great concern for many canine patients.

Editing credits to M.W. Dryden, R.R. Ganta.

Dr. Payne is an assistant professor at Kansas State University in the Department of Diagnostic Medicine/Pathobiology. She received her DVM from Kansas State University in 1971 and worked in small animal clinical practice in Virginia for 23 years before returning to the university. Her Ph.D. was earned in 2000 for research in insecticide resistance of the cat flea.


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