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Veterinarian Technician April 2009 (Vol 30, No 4)

Parasites 100 — Working with the basic CAPC recommendations

by Dwight D. Bowman, MS, PhD

    One of the primary goals of the Companion Animal Parasite Council (CAPC) is its mission to foster animal and human health while preserving the human–animal bond through recommendations for the diagnosis, treatment, prevention, and control of parasitic infections. This mission is supported by six basic CAPC recommendations.

    To convince clients about the value of complying with these guidelines, veterinarians and their staff need to be in fairly good agreement with the principles. Therefore, technicians need to become familiar with all parasites — ectoparasites and endoparasites alike.

    In the southeastern United States, where heartworm disease is common and hookworms are prevalent, the use of year-round preventatives and the need for compliance are easy-to-understand concepts. However, in the northern states, where heartworms are considered to be transmitted seasonally, and in many of the western states, where heartworm transmission is often considered rare or nonexistent, annual prevention is not always embraced by practitioners, thereby making client compliance difficult.2

    The upper midwestern states have been one of the major centers for lack of compliance with respect to the administration of preventatives, and the occurrence of infection in dogs that are receiving preventatives is, therefore, likely because of the lack of certainty as to when to start and stop heartworm therapy.2–5 In addition, some western states refuse to admit that there is local transmission of heartworms, although veterinarians in almost every western state claim that it occurs.6 The unwillingness to accept the possibility of heartworm transmission in certain areas has allowed it to spread throughout the United States since its first appearance in Hennepin County, Minnesota, in 1937.7,8

    Zoonotic Potential

    Educating clients about the potential risk associated with zoonotic disease is a key role for veterinary technicians, who need to recognize the zoonotic potential of such parasites as Toxocara canis, Toxoplasma gondii, Trichinella spiralis, and Ancylostoma braziliense.

    With roundworms, transmission can occur throughout the winter. As soon as the egg has been ingested, the infective larva remains capable of hatching and causing disease. A national survey of dogs in US shelters showed that adults are commonly infected with T. canis and shed eggs into the environment.9 However, because academic parasitologists were unable to experimentally infect dogs with T. canis until fairly recently, there was the long-running misconception that adult dogs do not get roundworms. It happens and is not uncommon — in the national survey, more than 15% of shelter dogs older than 3 years of age had roundworms.9

    T. canis eggs are potential zoonotic agents, and recent work shows that about 14% of people in the United States are infected with the larval stage of this worm.10 These infections are acquired by ingestion of T. canis eggs from contaminated soil or on soil-contaminated objects. About the only way to minimize the risk for infection is to reduce the number of dogs — both puppies and adults — that are shedding eggs.11 The way to accomplish this is to work harder at compliance and to follow regular deworming and fecal examination protocols to prevent dogs from shedding eggs into the environment.

    Along this same line of thought, it is often forgotten that cats serve as hosts for T. cati, which is now considered a cause of larval toxocariasis in humans. In addition, cats are perhaps even better hosts than dogs for the hookworm A. braziliense, the causative agent of cutaneous larval migrans in the southeastern United States. Cats also should be given year-round treatment with broad-spectrum heartworm anthelmintics that have activity against parasites with zoonotic potential. Cats that are infected with heartworms can develop severe disease even though they may never develop adult worms or patent infections.12

    Prevention and Intervention

    There are good reasons for complying with all six basic components outlined in the CAPC guidelines. The prevention of heartworm and routine internal parasites is a good place to start, but flea and tick control likewise is important. Technicians need to understand that nothing can destroy a relationship between a pet and its owner faster than a member of the family developing a fleabite allergy or tick-borne disease.

    Raw food and contaminated water can serve as sources of many parasitic infections. The following parasites can be transmitted by raw food to pets:

    Dogs and Cats

    — Roundworms

    — Hookworms

    — Tapeworms

    Trichinella (trichinosis)

    — Protozoa

    — Trematodes

    Cats

    Toxoplasma

    Dogs

    Nanophyetus salmincola (salmon poisoning disease)

    Finally, the only way to determine whether a prevention program is working is to monitor the success of intervention — and for this we have fecal examinations and heartworm antigen detection. Technicians, therefore, need to address these concerns with pet owners. For example, teaching owners how to collect freshly voided fecal samples from a pet can yield more accurate fecal test results.

    Subsequent Parasite 100 columns from the CAPC will address other recommendations that require the intervention of technicians in protecting the human–animal bond and fostering healthy client interactions.

    Dr. Bowman reported no potential conflict of interest relevant to this article. The CAPC receives financial support from pharmaceutical companies.

    1. McCall JW, Cowgill LM, Plue RE, Evans T. Prevention of natural acquisition of heartworm infection in dogs by monthly treatment with ivermectin. In: Proceedings of the Heartworm Symposium '83. Orlando, Fla.: American Heartworm Society; 1983:150-152.

    2. Hartogensis M. CVM adverse drug data show increase in reports of lack of effectiveness for heartworm prevention drugs. FDA Vet 2005;20(6):2-3.

    3. Hampshire VA. Evaluation of efficacy of heartworm preventive products at the FDA. Vet Parasitol 2005;133(2/3):191-195.

    4. Bowman D. Heartworm disease: new information and implications for the northern U.S. In: The NAVC Conference Proceedings; Orlando, Fla.: Jan. 19-23, 2008.

    5. Bowman D. Heartworm disease: new information and implications for the southern U.S. In: The NAVC Conference Proceedings; Orlando, Fla.: Jan. 19-23. 2008.

    6. Bowman DD, Torre CJ, Mannella C. Survey of 11 western states for heartworm (Dirofilaria immitis) infection, heartworm diagnostic and prevention protocols, and fecal examination protocols for gastrointestinal parasites. Veterinary Therapeutics 2007;8(4): 293-304.

    7. Roncalli RA. Tracing the history of heartworms: a 400-year perspective. In: Recent Advances in Heartworm Disease: Symposium '98. Orlando, Fla.: American Heartworm Society; 1998:1-14.

    8. Schlotthauer JC, Hendrix CM, Robinson RA. Four decades of heartworm in Minnesota. In: Proceedings of the Heartworm Symposium '80. Orlando, Fla.: American Heartworm Society; 1980:5-6.

    9. Blagburn BL, Lindsay DS, Vaughan JL, et al. Prevalence of canine parasites based on fecal flotation. Compend Contin Educ Pract Vet 1996;18(5):483-509.

    10. Won K, Kruszon-Moran D, Schantz P, Jones J. National seroprevalence and risk factors for zoonotic Toxocara spp. infection. In: 56th Annual Meeting of the American Society of Tropical Medicine and Hygiene. Philadelphia, Pa.: American Society of Tropical Medicine and Hygiene; 2007: Abstract 134.

    11. Bowman DD. Successful and currently ongoing parasite eradication programs. Vet Parasitol 2006;139:293-307.

    12. Blagburn BL, Dillon AR. Feline heartworm disease: solving the puzzle. Vet Med 2007;Suppl.

    References »

    NEXT: Peer Reviewed — Anesthesia: Minimizing Risks in Senior Pets

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