title: Selamectin for the prevention of canine Dirofilaria immitis infection: field efficacy in client-owned dogs in a high risk area.
abstract: Dog owners and veterinarians in small animal practices began to waive prevention of canine heartworm disease after heartworm infections seemed to have disappeared in Brazil. After 2013, infection rates rebounded, and an evaluation of the efficacy of chemoprophylactic drugs became necessary. Included in this re-evaluation was the efficacy of selamectin in client-owned dogs residing in a high infection-risk area.
  
  
  
  The preventive efficacy of selamectin was evaluated by the topical application of selamectin to 24 client-owned dogs at the recommended rate (minimum of 6 mg/kg) by a veterinarian monthly for 36 months. Blood samples were collected before the first treatment and at the end of the study for testing to detect microfilariae by the modified Knott's test and Dirofilaria immitis antigens using a commercial antigen test. Exposure to risk of heartworm infection was confirmed by the presence of infection in dogs living in low-income communities within a 2 km radius from the homes of dogs in the study. The dogs were managed according to routine practice by the owners within each household throughout the study.
  
  
  
  All dogs tested negative by both tests after receiving topical treatment with selamectin monthly for 36 months. Testing of 204 dogs from the communities confirmed the presence of heartworm in the area by detection of microfilariae or D. immitis antigen in 44 dogs (21.6 %).
  
  
  
  Topical selamectin was 100 % effective for D. immitis prevention in 24 dogs that received monthly treatments by a veterinarian. Detection of heartworm infections in untreated dogs in the area suggests that clients need to be better informed regarding the prevalence of D. immitis and the importance of maintaining regular preventive treatments.
authors.affiliation: Consultório Veterinário Fino Trato para Cão e Gato, Av. Armando Lombardi 800, loja 100 F, 22640-000, Rio de Janeiro, RJ, Brazil.
authors.forename: Maria de Fátima Chicarino Varajão
authors.initials: Mde F
authors.lastname: Moraes-da-Silva
authors.affiliation: Programa de Pós-Graduação em Medicina Veterinária - Clínica e Reprodução Animal, Faculdade de Veterinária, Universidade Federal Fluminense, Rua Vital Brazil Filho 64, 24230-340, Niterói, RJ, Brazil.
authors.forename: Flavya
authors.initials: F
authors.lastname: Mendes-de-Almeida
authors.affiliation: Fundação Oswaldo Cruz, Av. Brasil 4365, 21040-360, Rio de Janeiro, RJ, Brazil.
authors.forename: Livia
authors.initials: L
authors.lastname: Abdalla
authors.affiliation: Zoetis, Rua Henri Dunant, 1383, 4th floor, CEP: 04709-111, São Paulo, SP, Brazil.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Merlo
authors.affiliation: Departamento de Medicina e Cirurgia Veterinária, Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro, BR-465, km 7, 23890-000, Seropédica, RJ, Brazil.
authors.forename: Jonimar Pereira
authors.initials: JP
authors.lastname: Paiva
authors.affiliation: Programa de Pós-Graduação em Medicina Veterinária - Clínica e Reprodução Animal, Faculdade de Veterinária, Universidade Federal Fluminense, Rua Vital Brazil Filho 64, 24230-340, Niterói, RJ, Brazil. labarthe@fiocruz.br.|Fundação Oswaldo Cruz, Av. Brasil 4365, 21040-360, Rio de Janeiro, RJ, Brazil. labarthe@fiocruz.br.
authors.forename: Norma Vollmer
authors.initials: NV
authors.lastname: Labarthe
mesh_terms: D000287:Administration, Topical; D000818:Animals; D000871:Anthelmintics / Q000627:therapeutic use*; D001769:Blood / Q000469:parasitology; D001938:Brazil; D004183:Dirofilaria immitis / Q000187:drug effects*; D004184:Dirofilariasis / Q000517:prevention & control*; D004283:Dog Diseases / Q000517:prevention & control*; D004285:Dogs; D007559:Ivermectin / Q000031:analogs & derivatives* / Q000627:therapeutic use
chemical_list: D000871:Anthelmintics; D007559:Ivermectin; C414354:selamectin
keywords: Chemoprophylaxis; Dirofilaria immitis; Heartworm; Macrocyclic lactone; Preventive; Selamectin