Recent Heartworm Findings

Summary of reports indicating lack of efficacy of macrocyclic lactones for heartworm prevention using certain challenging strains*

1998: CVM first received complaints about ineffective ML products1

2001: CVM reported an increase in the number of reports indicating lack of efficacy of ML1

2011- 2013: Studies sponsored by multiple pharmaceutical companies and conducted by various investigators showed these results:

  • Oral ivermectin failed in 4 studies and 31/46 dogs2,3,4,5
  • Oral milbemycin oxime failed in 6 studies and 28/68 dogs2,3,4,6,7,
  • Injectable moxidectin failed in 1 study and 4/4 dogs8
  • Topical selamectin failed in 2 studies and 15/16 dogs2,4
  • Transdermal moxidectin failed in 1 study and 1/8 dogs7
     

At least 3 strains of D. immitis tested: MP-3, JYD-34, JD2009-1

These challenging strains have been sourced from naturally infected dogs in GA, MO and AR

Studies varied in protocol. For example, variations included number of dogs, consecutive monthly doses administered, number of heartworm larvae with which each dog was infected, as well as heartworm strain

*Products tested are labeled for ongoing monthly use. The prevalence of MP-3, JYD-34 and JD2009-1 strains of heartworm is unknown, so the relevance of these studies cannot be extrapolated to heartworm strains in general. Additional research is needed to determine the prevalence of MP-3-, JYD-34- and JD2009-1-like isolates in the field.

Animals treated 45 days post infection not included

 

Read more about how Advantage Multi® for Dogs (imidacloprid + moxidection) performed:


 

In these laboratory studies, Advantage Multi® for Dogs outperformed leading heartworm preventives against the laboratory-maintained MP-3 and JYD-34 strains after a single treatment versus one or three treatments of other products tested, under the conditions of these studies.2,4,7**

 

**Products tested are labeled for ongoing monthly use. The prevalence of MP-3 and JYD-34 strains of heartworm is unknown, so the relevance of these studies cannot be extrapolated to heartworm strains in general. Additional research is needed to determine the prevalence of MP-3- and JYD-34-like isolates in the field.

1. Hampshire VA. (2005). Evaluation of efficacy of heartworm preventive products at the FDA. Vet Parasitol. 133:191-195.
2. Blagburn BL, Dillon AR, Arther RG, et al. (2011). Comparative efficacy of four commercially available heartworm preventive products against the MP3 laboratory strain of Dirofilaria immitis. Vet Parasitol. 176:189–194.
3. Snyder DE, Wiseman S, Cruthers LR, et al. (2011). Ivermectin and milbemycin oxime in experimental adult heartworm (Dirofilaria immitis) infection of dogs. J Vet Intern Med. 251:61-64.
4 Data on file. Bayer HealthCare, Animal Health.
5. Kaminsky R, Lizundia R, Blagburn B, et al. (2013). Efficacy studies in dogs demonstrate resistance of Dirofilaria against ivermectin and other macrocyclic lactones. In: Proceedings. 58th Annual Meeting of the American Association of Veterinary Parasitologists; July 20-23; Chicago, IL. 66.
6. Snyder DE, Wiseman S, Bowman DD, et al. (2011). Assessment of the effectiveness of a combination product of spinosad and milbemycin oxime on the prophylaxis of canine heartworm infection. Vet Parasitol. 180(3-4):262-266.
7. Data on file. Bayer HealthCare, Animal Health.
8. Bowman D, Lee A, Harrington L, et al. (2013). Testing the efficacy of an injectable moxidectin formulation (ProHeart® 6) against a field isolate of canine heartworm. In: Proceedings. 58th Annual Meeting of the American Association of Veterinary Parasitologists; July 20-23; Chicago, IL. 66.

Product Label

CAUTION: Federal (U.S.A.) law restricts this drug to use by or on the order of a licensed veterinarian. WARNING: DO NOT ADMINISTER THIS PRODUCT ORALLY. For the first 30 minutes after application ensure that dogs cannot lick the product from application sites on themselves or other treated animals. Children should not come in contact with the application sites for two (2) hours after application. (See Contraindications, Warnings, Human Warnings, and Adverse Reactions, for more information.) CONTRAINDICATIONS: Do not use this product on cats.

 

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