RESUMO
A study was conducted in cattle experimentally infested with Psoroptes ovis to compare the prophylactic control against P. ovis provided by a long-acting injectable formulation of ivermectin to that of a commercially available injectable formulation of doramectin. Thirty Holstein steers were used. Animals were allocated by restricted randomization based on Day 0 body weight, forming six replicates of five animals each. Within each replicate, one animal was randomly allocated to one of the following treatment groups, with ivermectin and doramectin administered subcutaneously where indicated: (1) untreated controls; (2) ivermectin long-acting injectable (LAI) 630 mcg/kg, 56 days before challenge; (3) ivermectin LAI 630 mcg/kg, 42 days before challenge; (4) ivermectin LAI 630 mcg/kg, 35 days before challenge; or (5) doramectin 200 mcg/kg, 35 days before challenge. Animals were housed in individual pens 1 week prior to treatment. All animals were experimentally infested with P. ovis mites in the area between the shoulders, on the same day. Live mites were counted in scrapings from mange lesions at 2 sites on each animal 14, 21 and 28 days after challenge. Live mites were found in 33, 67 and 83% of the untreated controls on each respective evaluation. No P. ovis mites were found in steers treated with ivermectin LAI. Those animals showed lower (P < 0.05) mite counts than untreated controls on evaluations conducted 21 and 28 days after challenge. These results indicate that the ivermectin long-acting injectable formulation prevents induced infestations by P. ovis for at least 56 days after treatment. Doramectin injectable formulation, used at 200 mcg/kg, did not have a prophylactic effect 35 days after treatment.
Assuntos
Anti-Helmínticos/administração & dosagem , Doenças dos Bovinos/prevenção & controle , Ivermectina/administração & dosagem , Infestações por Ácaros/veterinária , Ácaros/crescimento & desenvolvimento , Dermatopatias/veterinária , Animais , Anti-Helmínticos/normas , Bovinos , Doenças dos Bovinos/parasitologia , Preparações de Ação Retardada , Injeções Subcutâneas/veterinária , Ivermectina/análogos & derivados , Ivermectina/normas , Masculino , Infestações por Ácaros/prevenção & controle , Ácaros/efeitos dos fármacos , Dermatopatias/parasitologia , Dermatopatias/prevenção & controleRESUMO
Three trials including 42 sheep were conducted in Brazil or Germany to evaluate the therapeutic (two trials) and prophylactic (one trial) efficacy of an ivermectin controlled release capsule (CRC) against Psoroptes ovis infestation. In one therapeutic trial naturally infested sheep were used while in the other trials infestations were experimentally induced. In each trial half of the animals were treated on Day 0 with one ivermectin controlled release capsule that delivers ivermectin at a rate of 1.6 mg/day for approximately 100 days, that is 20 mcg/kg/day to a 80 kg animal, while the other half remained untreated. In both therapeutic trials mites were counted in skin scrapings and their presence was recorded at predilection sites one day before treatment and at weekly intervals from Day 7 to Day 56. In the trial conducted to evaluate the prophylactic efficacy the sheep were experimentally infested with P. ovis 21 and 28 days post-treatment and mites were counted and recorded at predilection sites on Days 42, 49 and 56. The ivermectin controlled release capsule was completely effective in eliminating the P. ovis mites within 28 days of administration and it prevented the establishment of an infestation of P. ovis induced 21 and 28 days after administration.
Assuntos
Inseticidas/administração & dosagem , Ivermectina/administração & dosagem , Infestações por Ácaros/veterinária , Ácaros , Doenças dos Ovinos/prevenção & controle , Animais , Brasil , Preparações de Ação Retardada , Feminino , Alemanha , Inseticidas/uso terapêutico , Ivermectina/uso terapêutico , Masculino , Infestações por Ácaros/prevenção & controle , Ácaros/crescimento & desenvolvimento , Ovinos , Pele/parasitologiaRESUMO
The prophylactic efficacy of ivermectin against navel or scrotal myiasis in calves was evaluated in eight trials in Argentina and Brazil. In two trials, calves were injected subcutaneously with ivermectin at a dosage of at least 200 microg kg(-1) within 24 h of birth. In the other six trials, two with two-month-old calves and four with four-month-old or older calves, all calves were treated with ivermectin at a dosage of at least 200 microg kg(-1) immediately after castration. In all trials, calves were maintained together on pasture and naturally exposed to Cochliomyia hominivorax. Navel and scrotal wounds were examined for myiasis daily for at least 14 days. Incidence of navel and scrotal myiasis was significantly lower (P < 0.01) in treated calves than in control calves.
Assuntos
Doenças dos Bovinos , Inseticidas/uso terapêutico , Ivermectina/uso terapêutico , Infecção por Mosca da Bicheira/veterinária , Animais , Animais Recém-Nascidos , Argentina , Brasil , Bovinos , Incidência , Masculino , Infecção por Mosca da Bicheira/epidemiologia , Infecção por Mosca da Bicheira/prevenção & controle , Escroto , Estações do AnoRESUMO
Systemic efficacy of ivermectin applied topically was evaluated against the cattle tick, Boophilus microplus. Twenty cattle with induced infestations were randomly allocated to five groups of equal size based on the numbers of engorged female ticks which fell through the slatted floor of individual pens during the 3 days prior to treatments. Control cattle were non-medicated. Cattle in three groups were given ivermectin at 200, 500 or 1000 mcg kg-1 in a topical formulation applied along the backline from the withers to the rump; cattle in the fifth group were given ivermectin in an injectable formulation subcutaneously at 200 mcg kg-1. Individual 24-h tick collections were made three times weekly for 5 weeks after treatment. Engorged female B. microplus were incubated to determine effects on reproduction. Based on the numbers of engorged female B. microplus collected following treatments, overall efficacy of ivermectin applied topically at 200, 500 and 1000 mcg kg-1 was 50, 85 and 91%, respectively, whereas ivermectin given at 200 mcg kg-1 subcutaneously was 80% effective. The index of reproduction for ivermectin given topically was reduced by 84, 94 and 95%, respectively, and that for ivermectin subcutaneously was 94%. No significant differences (P greater than 0.05) were found for these variables between ivermectin given topically at 500 or 1000 mcg kg-1 versus 200 mcg kg-1 given subcutaneously.