• 1.

    Hampshire VA. Evaluation of efficacy of heartworm preventive products at the FDA. Vet Parasitol 2005; 133:191195.

  • 2.

    Snyder DEWiseman SCruthers LR, et al. Ivermectin and milbemycin oxime in experimental adult heartworm (Dirofilaria immitis) infection of dogs. J Vet Intern Med 2011; 25:6164.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 3.

    Blagburn BLSpencer JANobles J, et al. American Heartworm Society Quarterly E-Bulletin. Heartworm preventive failures: resistance, clinic or client compliance. Available at: www.heartwormsociety.org/enewsletter/march2008/enewsletter_p=13.html. Accessed Dec 20, 2010.

    • Search Google Scholar
    • Export Citation
  • 4.

    Blair LSWilliams EEwanciw DV. Efficacy of ivermectin against third-stage Dirofilaria immitis larvae in ferrets and dogs. Res Vet Sci 1982; 33:386387.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 5.

    Clemence RGSarasola PGenchi C, et al. Efficacy of selamectin in the prevention of adult heartworm (Dirofilaria immitis) infection in dogs in northern Italy. Vet Parasitol 2000; 91:251258.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 6.

    Genchi CPoglayen GKramer LH, et al. Efficacy of moxidectin for the prevention of adult heartworm (Dirofilaria immitis) infection in dogs. Parassitologia 2001; 43:139141.

    • Search Google Scholar
    • Export Citation
  • 7.

    Lok JBKnight DHNolan TJ, et al. Efficacy of an injectable, sustained-release formulation of moxidectin in preventing experimental heartworm infection in mongrel dogs challenged 12 months after administration. Vet Parasitol 2005; 128:129135.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 8.

    Lok JBWashabau RJHeaney K, et al. Six-month prophylactic efficacy of moxidectin sustained release (SR) injectable for dogs against experimental heartworm infection in growing puppies. Vet Parasitol 2005; 133:233241.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 9.

    McTier TLShanks DJWatson P, et al. Prevention of experimentally induced heartworm (Dirofilaria immitis) infections in dogs and cats with a single topical application of selamectin. Vet Parasitol 2000; 91:259268.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 10.

    Prichard RK. Is anthelmintic resistance a concern for heartworm control? What can we learn from the human filariasis control programs? Vet Parasitol 2005; 133:243253.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 11.

    American Heartworm Society. Diagnosis, prevention and management of heartworm (Dirofilaria immitis) infectrion in dogs. Available at: www.heartwormsociety.org/veterinary-resources/canine-guidelines.html. Accessed Dec 29, 2010.

    • Search Google Scholar
    • Export Citation
  • 12.

    Glickman LTGrieve RBBreitschwerdt EB, et al. Serologic pattern of canine heartworm (Dirofilaria immitis) infection. Am J Vet Res 1984; 45:11781183.

    • Search Google Scholar
    • Export Citation
  • 13.

    Selby LACorwin RMHayes HM Jr. Risk factors associated with canine heartworm infection. J Am Vet Med Assoc 1980; 176:3335.

  • 14.

    Theis JHFranti CLambert L, et al. Risk factors for heartworm infection in dogs living in Sierra Nevada foothills and Sacramento Valley counties; public health implications. Calif Vet 1984; 38:1317.

    • Search Google Scholar
    • Export Citation
  • 15.

    Walters LL. Risk factors for heartworm infection in Northern California. In: Soil MDKnight DH, eds. Proceedings of the heartworm symposium ′95. Batavia, Ill: American Heartworm Society 1995;526.

    • Search Google Scholar
    • Export Citation
  • 16.

    Knight DHLok JB. Seasonality of heartworm infection and implications for chemoprophylaxis. Clin Tech Small Anim Pract 1998; 13:7782.

  • 17.

    Nelson CTMcCall JWRubin SB, et al. 2005 guidelines for the diagnosis, prevention and management of heartworm (Dirofilaria immitis) infection in dogs. Vet Parasitol 2005; 133:255266.

    • Crossref
    • Search Google Scholar
    • Export Citation

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Risk factors associated with failure of heartworm prophylaxis among members of a national hunting dog club

Barton W. Rohrbach VMD, MPH, DACVPM1, Agricola Odoi BVM, PhD2, and Sharon Patton PhD3
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  • 1 Department of Comparative Medicine, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996.
  • | 2 Department of Comparative Medicine, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996.
  • | 3 Department of Comparative Medicine, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996.

Abstract

Objective—To identify practices associated with failure of heartworm prophylaxis among dog and kennel owners and dog trainers.

Design—Online survey and mail-in questionnaire.

Sample—708 members of a national hunting dog club.

Procedures—Heartworm prevention practices used by respondents that reported failure of prophylaxis were compared with practices used by respondents that reported success.

Results—Univariate analyses indicated failure of heartworm prophylaxis was inversely related to the number of dogs under a respondent's care. Year-round prophylactic practice was not significantly associated with reduced odds of failure, and efforts to control exposure to mosquitoes were similar among the comparison groups. Respondents reporting prophylaxis failure were more likely to test for heartworm infection ≥ 1 time/y, compared with those reporting success. In a multivariable analysis, residence south of the Virginia-North Carolina state line (ie, the 37th geographic parallel), testing for heartworm infection < once a year when the test was administered prior to April 1, and keeping dogs outdoors for longer periods at dusk, at dawn, or after dark were associated with increased odds of prophylaxis failure.

Conclusions and Clinical Relevance—Veterinarians should stress the importance of annual heartworm testing 6 to 7 months after the last possible date of exposure to heartworm, regardless of whether a dog receives prophylactic treatment year-round. Reducing the number of hours dogs spend outdoors at dusk, at dawn, or after dark may reduce the odds of heartworm disease even when dogs are given preventive treatment.

Abstract

Objective—To identify practices associated with failure of heartworm prophylaxis among dog and kennel owners and dog trainers.

Design—Online survey and mail-in questionnaire.

Sample—708 members of a national hunting dog club.

Procedures—Heartworm prevention practices used by respondents that reported failure of prophylaxis were compared with practices used by respondents that reported success.

Results—Univariate analyses indicated failure of heartworm prophylaxis was inversely related to the number of dogs under a respondent's care. Year-round prophylactic practice was not significantly associated with reduced odds of failure, and efforts to control exposure to mosquitoes were similar among the comparison groups. Respondents reporting prophylaxis failure were more likely to test for heartworm infection ≥ 1 time/y, compared with those reporting success. In a multivariable analysis, residence south of the Virginia-North Carolina state line (ie, the 37th geographic parallel), testing for heartworm infection < once a year when the test was administered prior to April 1, and keeping dogs outdoors for longer periods at dusk, at dawn, or after dark were associated with increased odds of prophylaxis failure.

Conclusions and Clinical Relevance—Veterinarians should stress the importance of annual heartworm testing 6 to 7 months after the last possible date of exposure to heartworm, regardless of whether a dog receives prophylactic treatment year-round. Reducing the number of hours dogs spend outdoors at dusk, at dawn, or after dark may reduce the odds of heartworm disease even when dogs are given preventive treatment.

Contributor Notes

Supported by Novartis Animal Health Incorporated.

Presented as an oral presentation at the 84th Annual Meeting of the American Society of Parasitologists, Knoxville, Tenn, August 2009.

Address correspondence to Dr. Rohrbach (brohrbac@utk.edu).