Abstract
BackgroundPrior work has shown that the levels of moxidectin in dogs treated with Advantage Multi® for Dogs (Bayer Animal Health) remain at a high plasma concentration for the full month after application. The objective of this study was to demonstrate the efficacy of 10% imidacloprid + 2.5% moxidectin topical solution (Advantage Multi® for Dogs, also known as Advocate® for Dogs) for the prevention of heartworm infection and disease 30 days after just one application.MethodsTwo groups of eight dogs each were included. Dogs in Group 1 received the product (Advantage Multi® for Dogs) while those in Group 2 remained as nontreated controls. All dogs entering the study completed a physical examination including examination for Dirofilaria immitis antigen and circulating microfilariae. Dogs in Group 1 were treated on Study Day (SD) –30 as per the label recommendation. Thirty days later (SD 0) dogs in Groups 1 and 2 were subcutaneously infected in the inguinal region with approximately 50 infective third-stage D. immitis larvae (“Missouri” isolate). Blood was collected on SDs 120 and 147 for examination for D. immitis antigen and circulating microfilariae. On SD 148, all animals were euthanized and necropsied for recovery of adult heartworms. All procedures were performed in accordance with the VICH GL9 guidelines.ResultsExamination and worm counts made at necropsy showed no heartworms in the treated dogs (Group 1) compared with six of eight nontreated dogs (Group 2) with heartworms (range of 2–33). The treated dogs (Group 1) had significantly fewer heartworms (p < 0.05) compared with the nontreated controls (Group 2).ConclusionThe results demonstrated that 10% imidacloprid + 2.5% moxidectin topical solution (Advantage Multi® for Dogs) is efficacious for the prevention of heartworm infection and disease all month long with no observation of treatment-related adverse events.
Highlights
Prior work has shown that the levels of moxidectin in dogs treated with Advantage Multi® for Dogs (Bayer Animal Health) remain at a high plasma concentration for the full month after application
In 2003, it was shown that when eight dogs were administered 10% imidacloprid + 2.5% moxidectin topical solution and subsequently infected with 300 Uncinaria stenocephala 18 days later, neither immature nor mature adult hookworms were present 21 days after infection, while the eight nontreated dogs harbored a mean of 4.6 (SD ± 3.9) immature adults and 8.1 (SD ± 4.3) mature adults [1]
In 2008, a similar study with hookworms of the genus Ancylostoma was reported in which cats and dogs were respectively administered each month, as per label, either five monthly treatments of 10% imidacloprid + 1% moxidectin topical solution (Advantage Multi® for Cats) or four monthly treatments of 10% imidacloprid + 2.5% moxidectin topical solution (Advantage Multi® for Dogs) [2]
Summary
Prior work has shown that the levels of moxidectin in dogs treated with Advantage Multi® for Dogs (Bayer Animal Health) remain at a high plasma concentration for the full month after application. The objective of this study was to demonstrate the efficacy of 10% imidacloprid + 2.5% moxidectin topical solution (Advantage Multi® for Dogs, known as Advocate® for Dogs) for the prevention of heartworm infection and disease 30 days after just one application. Persistent efficacy of topical imidacloprid + moxidectin (Advantage Multi®, Bayer Animal Health) was first demonstrated in dogs and cats against hookworm infections. Necropsy examinations conducted after establishment of patent infections in the nontreated cats showed none of the six treated cats had hookworms, while a mean of 62.5 adult A. tubaeforme was recovered from the nontreated cats. Each of the six treated and six nontreated dogs were orally infected with U. stenocephala larvae and Ancylostoma caninum larvae 22 and 23 days, respectively, after the fourth treatment. One adult A. caninum was recovered from one treated dog, while a mean of 41.3 A. caninum was recovered from the nontreated dogs
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