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1.
A controlled trial was conducted to evaluate the efficacy of the intraruminal ivermectin controlled-release capsule (CRC) (IVOMEC Maximizer CR Capsule for Sheep, Merial Ltd.) against induced incoming third-stage larvae and established adult infections with some rarer gastrointestinal nematode parasites of sheep. Twenty-one worm-free lambs were allocated by restricted randomisation based on body weight within sex to one of the following treatments: unmedicated control, ivermectin CRC given on Day 0 prior to induced infection, and ivermectin CRC given on Day 70 after establishment of induced infection. The ivermectin CRC delivers ivermectin at a minimum dose rate of 20 microg/kg/day for 100 days. Infections were induced by daily administration of third-stage larvae for five consecutive days. Nematodes were counted on Day 84, 14 days after treatment of established infection. The treatment with the ivermectin CRC prevented the establishment of Ostertagia leptospicularis, O. ostertagi, Bunostomum trigonocephalum, Cooperia oncophora, C. punctata, C. surnabada, Nematodirus helvetianus, N. roscidus and Strongyloides papillosus by >99% as compared with the untreated controls (p < 0.01). The administration of the ivermectin CRC reduced established adult infections of O. ostertagi, B. trigonocephalum, C. oncophora, C. punctata, C. surnabada, N. roscidus and S. papillosus by >99% (p < 0.01), and reduced established adult infections of O. leptospicularis and N. helvetianus by 96.5 and 98.4% (p < 0.01), respectively.  相似文献   

2.
Two studies were conducted to determine the persistent efficacy of doramectin pour-on against an artificial, trickle challenge of mixed nematodes in calves. In each study, 42, 4-8 months old calves were randomly assigned into four groups of 10 animals each (T1-T4), plus two larval-viability monitor animals. All animals were treated with fenbendazole (10 mg kg(-1)) 14 days prior to the start of the study to clear any existing infection. Doramectin pour-on at 500 microg kg(-1) was used on each animal in Groups T2, T3, and T4 with intervals of 1 week (Day 0, 7, and 14, respectively). Calves in Group T1 were treated with saline solution on Day 0 and at the same volumetric rate (1 ml 10 kg(-1)) as the doramectin treated animals. All treatments were applied in a single passage along the midline of the back, from the withers to the tailhead. Subsequently, trickle inoculations with infective larvae were administered to all calves for 22 consecutive days (Days 14-35). Doramectin pour-on provided > or = 91.9% efficacy against challenge with Dictyocaulus viviparus, Haemonchus spp., and Ostertagia ostertagi for up to 35 days post-treatment and against challenge with Cooperia oncophora, Cooperia punctata, and Oesophagostomum radiatum for up to 28 days post-treatment.  相似文献   

3.
The main objective of the present study was to evaluate the accuracy of the faecal egg count reduction test (FECRT) to assess the resistance status of ivermectin (IVM)-resistant isolates of the cattle nematodes Ostertagia ostertagi and Cooperia oncophora, using the controlled efficacy test (worm counts) as a reference. The second objective was to investigate whether both IVM-resistant isolates showed side-resistance against moxidectin (MOX) under controlled conditions. Thirty male Holstein calves were experimentally infected with 25,000 L3 of an IVM-resistant O. ostertagi isolate and 25,000 L3 of an IVM-resistant C. oncophora isolate. Twenty-eight days later the calves were randomly divided into 2 treatment groups and 1 untreated control group. Animals in groups 1 and 2 received MOX (Cydectin(?) 1%, Pfizer) and IVM (Ivomec(?) 1%, Merial) respectively, by subcutaneous injection at a dose rate of 0.2mg/kg bodyweight. Faecal samples were collected 7 and 14days after treatment and animals were necropsied 14/15days post-treatment. Both the FECRT and the controlled efficacy test demonstrated that the O. ostertagi and C. oncophora isolates were resistant against IVM, with efficacies below 90%. The IVM-resistant O. ostertagia isolate was still susceptible to MOX treatment, as shown by over 99% reduction in egg counts and worm burden. The FECRT suggested borderline resistance against MOX in the IVM-resistant C. oncophora isolate, with egg count reductions between 97% (95% CI: 76; 100) at day 7 and 86% (95% CI: 49; 96) at day 14. However, the controlled efficacy test clearly showed MOX-resistance, with a decrease of only 31% (95% CI: -12; 57) in C. oncophora worm numbers. After MOX treatment, a significantly lower number of eggs per female C. oncophora worms was counted compared to the control group (43% reduction). Due to this reduced fecundity, the FECRT may fail to detect MOX-resistance.  相似文献   

4.
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.  相似文献   

5.
The residual effect of treatment with ivermectin after experimental reinfection in calves was tested. Twenty-four calves were divided into 6 groups of 4 calves each. All calves received a primary infection of 50,000 larvae of both Ostertagia ostertagi and Cooperia oncophora and 1000 Dictyocaulus viviparus larvae. Calves of group 1 remained untreated, and all other calves were treated 21 days after primary infection (0.2 mg/kg injected subcutaneously). Calves of groups 1 and 2 were slaughtered 7 days later. Calves of groups 3-6 were reinfected with the same number of larvae 3 days, 1, 3 and 6 weeks after treatment respectively. Slaughter was 21 days after reinfection. Based on post-mortem worm counts the efficacy of ivermectin after primary infection was 99.7% for O. ostertagi, 95.1% for C. oncophora and 100% for D. viviparus. A residual effect was present for at least one week, but could not be observed 3 weeks after treatment.  相似文献   

6.
OBJECTIVE: To evaluate efficacy of topically administered doramectin against eyeworms, lungworms, and gastrointestinal nematodes of cattle. ANIMALS: 400 cattle (20 cattle in each of 20 trials). PROCEDURE: Trials were conducted in North America; natural and experimentally induced infections were used. In each trial, cattle were allocated randomly to control (placebo [saline [0.9% NaCl] solution at 1 ml/10 kg of body weight] or untreated; n = 10) or doramectin-treated (500 microg/kg of body weight; 10) groups. Treatments were applied in a single passage along the midline of the back, from the withers to the tailhead. Cattle were euthanatized > or =14 days after treatment, and worm burdens were determined by use of standard techniques. RESULTS: Efficacy of doramectin was > or =95.3% against adults of Thelazia gulosa, T skrjabini, Dictyocaulus viviparus, Haemonchus contortus, H placei, Ostertagia lyrata, O ostertagi, Trichostrongylus axei, Bunostomum phlebotomum, Capillaria spp, Cooperia oncophora, C pectinata, C punctata, C spatulata, C surnabada, Nematodirus spathiger, Strongyloides papillosus, T colubriformis, Oesophagostomum radiatum, and Trichuris spp. Efficacy was 95.1% against fourth-stage larvae of D viviparus, H placei, O lyrata, O ostertagi, T axei, C oncophora, C punctata, C spatulata, C surnabada, N helvetianus, T colubriformis, O radiatum, and Trichuris spp. In addition, efficacy against inhibited fourth-stage larvae of O ostertagi and Ostertagia spp was > or =98.1%. CONCLUSIONS AND CLINICAL RELEVANCE: A single topical application of doramectin pour-on was efficacious against a broad range of nematode species in cattle.  相似文献   

7.
Duplicate studies in France and Northern Ireland were carried out to determine the persistent efficacy of topical moxidectin and doramectin against natural infections of Cooperia oncophora. In each study, groups of 15 nematode-na?ve calves were treated either with topical doramectin or moxidectin, and put out to graze on pasture contaminated with C. oncophora infective larvae. The persistent efficacy for preventing establishment of infection was assessed by the time to faecal egg excretion of C. oncophora eggs. It was found that the moxidectin treatment prevented infection for less than 10 days and the effect of doramectin lasted for 24 days.  相似文献   

8.
Objective To assess the persistent activity of injectable formulations of abamectin and doramectin against gastrointestinal nematodes of cattle.
Design Controlled slaughter study assessing residual efficacy.
Procedure Nematode-free calves were treated with abamectin or doramectin (each at a dose of 200 μg/kg) and infections then induced with repeated doses of infective larvae of Trichostrongylus axei, Haemonchus placei, Ostertagia ostertagi and Cooperia species. The duration of challenge ranged from 14 to 28 days. The calves were slaughtered at either 38/39 or 45/46 days after the treatments and nematodes recovered from the gastro-intestinal tract.
Results Significant reductions in numbers of O ostertagi occurred for both abamectin and doramectin treatments (> 93%) relative to counts in untreated calves, when challenge was administered up to 21 days after treatment. For T axei and Cooperia spp significant reductions occurred when the challenge occurred for 14 days after treatment (99%). Although differences from untreated animals were not significant, the results for H placei suggested high efficacy (> 85%) for up to 21 days for doramectin and up to 28 days for abamectin.
Conclusion There was no significant difference between abamectin and doramectin for any parasite at any challenge point, indicating that there is equivalent persistent activity of doramectin and abamectin against important gastrointestinal nematodes of cattle.  相似文献   

9.
Persistent anthelmintic activity of ivermectin in cattle   总被引：1，自引：0，他引：1  
Two studies are described which demonstrate the persistent activity of ivermectin injected subcutaneously into cattle at 200 micrograms/kg in preventing the establishment of induced infections with the gastrointestinal parasites Ostertagia ostertagi and Cooperia oncophora and the lungworm Dictyocaulus viviparus. These results indicated a reduction in mean worm count compared with the control group for O ostertagi of more than 99, 45 and 94 per cent with a seven, 14 or 21 day interval between treatment with ivermectin and the administration of infective larvae, respectively, in trial 1 and more than 99, more than 99 and 99 per cent at seven, 10 or 14 days, respectively, in trial 2. Corresponding values against C oncophora were 99, 0 and 45 per cent at seven, 14 and 21 days in trial 1 and more than 99, 84 and 31 per cent at seven, 10 and 14 days in trial 2. Against D viviparus, reduction in counts were more than 99, 98 and more than 99 per cent at seven, 14 and 21 days, respectively, in trial 1 and 100, 100 and 100 per cent at seven, 10 and 14 days, respectively, in trial 2. The relevance of these results to the build-up of infective larvae on pasture and infection in cattle is discussed.  相似文献   

10.
Efficacy of ivermectin in a topical formulation was evaluated in cattle against adult gastrointestinal and pulmonary nematode infections (experiment 1, n = 24), the 2nd- and 3rd-stage larvae of Hypoderma spp (experiment 2, n = 12), and the biting louse Damalinia bovis (experiment 3, n = 12). Nematode infections were induced and grubs and lice were naturally acquired. Treatments consisted of a single dose of ivermectin in a topical formulation of 200, 500, or 1,000 micrograms/kg of body weight in experiment 1 or 500 micrograms/kg in experiments 2 and 3. At 1,000 micrograms/kg, ivermectin was 100% effective against Ostertagia ostertagi, Trichostrongylus colubriformis, Oesophagostomum radiatum, Nematodirus helvetianus, Haemonchus placei, and Dictyocaulus viviparus and was greater than 99% effective against Cooperia oncophora, C punctata, and T axei. At 500 micrograms/kg, the efficacy was 100% against C oncophora, C punctata, O ostertagi, T axei, Oes radiatum, N helvetianus, Haem placei, and Dict viviparus and greater than 99% against T colubriformis. At 200 micrograms/kg, the efficacy was 100% against Oes radiatum, Haem placei, and Dict viviparus, greater than 99% for O ostertagi, 96% for C oncophora, 86% for C punctata, 90% for T axei, 85% for T colubriformis, and 71% for N helvetianus. At 500 micrograms/kg, ivermectin was highly effective against the grubs Hypoderma bovis and H lineatum and eliminated the louse Damalinia bovis.  相似文献   

11.
Two studies were performed to compare the persistent efficacy of doramectin and ivermectin in swine experimentally infested with Sarcoptes scabiei var. suis. In the Study 1, 84 pigs were treated with doramectin, ivermectin, or saline solution on Day 0. Pigs were then challenged with mites on Days 0, 7, 14, 21, 28, 35, or 42. Weekly evaluations were performed for 5 weeks following challenge with mites. Weekly evaluations included physical examination for clinical signs of sarcoptic mange and collection of skin scrapings for determination of mite counts. In the Study 2, 80 pigs were treated with doramectin, ivermectin, or saline solution on Day 0, and challenged with mites on Days 3, 6, 9, 12, 15, 18, 21, 24, or 27. Weekly evaluations were performed for 6 weeks after challenge exposure. All negative-control (saline-treated) animals in both studies developed evidence of mite infestation. In the Study 1, doramectin prevented mite infestations 7 days longer than ivermectin. Results from the Study 2 indicated that the persistent efficacy of doramectin was 18 days on the basis of mite recovery. This was twice as long as the persistent efficacy of ivermectin, which was 9 days on the basis of mite recovery.  相似文献   

12.
Three studies were conducted to evaluate the persistent efficacy of doramectin injectable solution against experimental challenges with infective larvae of Cooperia punctata and Dictyocaulus viviparus. In each study, four groups of ten randomly-assigned calves, negative for trichostrongyle-type eggs on fecal examination, were treated subcutaneously in the midline of the neck with saline (1 ml/50 kg) on Day 0 or doramectin (200 microg/kg = 1 ml/50 kg) on Day 0, 7, or 14. Two additional calves from the same pool of animals were randomly assigned as larval-viability monitors and received no treatment. On Days 14-28, approximately 1000 and 50 infective larvae of Cooperia spp. and D. viviparus, respectively, were administered daily by gavage to each animal in Groups T1-T4. On Day 28, the two larval-viability monitor calves were inoculated in a similar manner with a single dose of approximately 30000 and 2000 larvae of Cooperia spp. and D. viviparus, respectively. Equal numbers of calves from each treatment group were killed on Days 42-45, as well as the two viability monitor animals to enumerate worm numbers. A 2% or 5% aliquot of small intestinal contents and washings were examined for worm quantification and identification, while 100% of the lung recoveries were quantified and identified. For each study and across the three studies, geometric mean worm recoveries for each treatment group were calculated from the natural log transformed data (worm count + 1) and were used to estimate percentage reduction. In the three studies, doramectin injectable solution was 97.5% efficacious against lungworms for up to 28 days and was 99.8% efficacious in reducing infection resulting from challenge with infective larvae of C. punctata for at least 28 days post-treatment.  相似文献   

13.
The persistent anthelmintic effect of ivermectin as a topical treatment at 500 microg/kg was evaluated against induced infections of Ostertagia ostertagi, Trichostrongylus axei and Dictyocaulus vivparus in calves. The results showed a highly significant (P<0.001) anthelmintic activity for at least 14 days against O. ostertagi and T.axei (>99 per cent efficacies) and for at least 28 days (98 per cent efficacy) against D. viviparus.  相似文献   

14.
The persistent efficacy of the injectable and topical formulations of doramectin was compared against experimental challenges with infective larvae of Dictyocaulus viviparus in two separate studies. Four groups of 10 randomly-assigned calves, negative for lungworm larvae by the Baermann technique, were used in each study. Calves were treated subcutaneously in the midline of the neck or poured down the midline of the back with saline (1 ml/50 kg. injection: 1 ml/10 kg. pour-on) on Day 0 or doramectin (200 microg/kg = 1 ml/50 kg. injection: 500 microg/kg = 1 ml/10 kg. pour-on) on Day 0, 7, or 14. Two additional calves from the same pool of animals were randomly assigned as larval-viability monitors and received no treatment. Calves were inoculated daily with a gavage of approximately 100 larvae of D. viviparus from days 35 to 49 for the injectable study and days 28 to 42 for the pour-on study. The two larval viability monitor calves received approximately 3000 infective larvae in the same manner on Day 49 or 42 for the injectable and pour-on studies, respectively. Equal numbers of calves from each treatment group as well as the larval viability monitor calves were necropsied on days 14 and 15 after the last lungworm inoculation to enumerate the worm burden. The worms recovered were quantified and identified. For each study, geometric mean worm recoveries for each treatment group were back transformed from the natural log-transformed data (worm count +1) and were used to estimate percentage reduction. Doramectin injectable solution was 100.0% efficacious against lungworms for up to 49 days and the pour-on formulation was 100.0%, 93.1% and 81.5% effective in reducing lungworm infection resulting from challenge infection for up to 28, 35, and 42 days post-treatment, respectively.  相似文献   

15.
Two studies were conducted with doramectin topically administered at 500 microg/kg body weight to assess retention of therapeutic efficacy against nematode infections of cattle before, and after, simulated rainfall. In the first study, 50 heifers, with patent nematode infections, were allocated to one of five treatment groups. An untreated control group and one doramectin-treated group were not exposed to simulated rainfall. Simulated rainfall was applied at a rate of 25.4 mm of water in 35 min to three of the five groups: one group immediately before treatment, the second group 90 min after treatment, and the third group 24 h after treatment. Fecal samples were collected for determining egg counts 14 days after treatment. Percentage efficacy ranged from 97.3% to 100% in all treated calves, regardless of exposure to simulated rainfall. The second study involved 40 mixed-sex cattle that were allocated to one of four treatment groups (one saline control and three doramectin-treated groups). All cattle were confirmed to be free of nematode infections prior to oral gavage with infective larvae of Dictyocaulus viviparus, Cooperia oncophora, and Ostertagia ostertagi. Twenty-six days after infection, three groups were treated with doramectin pour-on and exposed to 20 mm of simulated rainfall over 40 min: one group 60 min before treatment, the second 20 min after treatment, and the third 40 min after treatment. Approximately two weeks after treatment, all cattle were necropsied for worm counts. In all treated groups, the percentage efficacy against O. ostertagi and D. viviparus was >99% to 100%. Percentage efficacy against Cooperia ranged from 97% to 98%. Results indicated that doramectin pour-on remains efficacious against nematodes of cattle when administered immediately before or after rainfall.  相似文献   

16.
Twelve Holstein calves were used to determine the prophylactic efficacy of ivermectin against challenge exposure with gastrointestinal and pulmonary nematodes. Two groups of 6 calves (mean body weight, 205 kg) each were formed by restricted randomization according to body weight. Group-1 calves served as nonmedicated controls. Each calf of group 2 was orally given one prototype sustained-release bolus designed to deliver ivermectin at a continuous daily dose of 8 mg. Third-stage nematode infective larvae were given to the calves on posttreatment days 28 and 42. The calves were euthanatized 77 or 78 days after treatment. Ivermectin was 100% effective (P less than 0.05) in preventing the establishment of infection by Haemonchus placei, Ostertagia ostertagi, Cooperia spp (C punctata, C oncophora, C surnabada), Nematodirus helvetianus, Oesophagostomum radiatum, and Dictyocaulus viviparus and was greater than 99% effective against Trichostrongylus axei. Incidental infection by Trichuris spp was reduced by 94% (P = 0.08).  相似文献   

17.
Two studies were conducted in North America to evaluate the persistent activity of doramectin injectable formulation against experimental challenge with Haemonchus placei. In both studies, calves were randomly assigned to 1 of 4 treatment groups (n = 10 per group) or a larval viability group (n = 2). Calves were treated subcutaneously in the lateral midline of the neck with saline (1 ml/50 kg) on Day 0, or with doramectin (200 mg/kg = 1 ml/50 kg) on Day 0, 7, or 14. Animals used to assess larval viability did not receive any treatment. Beginning on Day 14 and continuing through Day 28, each of the 40 treated calves were given approximately 300 infective larvae of H. placei per os. The two larval viability animals received approximately 10,000 larvae as a single dose on Day 28. Approximately two weeks later, all animals were slaughtered and the abomasum from each calf processed for nematode recovery. A 2% aliquot of abomasal contents plus wash was examined for enumeration and identification of nematodes. Geometric mean H. placei counts were calculated from the log (H. placei count +1) and used to estimate percentage reduction. Overall, doramectin was > or =96.9% efficacious in reducing infection with H. placei when challenged daily 14-28 days after treatment.  相似文献   

18.
A study was undertaken to determine the efficacy of the novel avermectin, doramectin, against experimental larval and adult infections of three species of nematode parasite important to cattle production in New Zealand. Eighteen worm-free dairy bull beef calves were randomly allocated on live weight to three similar treatment groups. Each calf was given 30,000 Ostertagia ostertagi, 20,000 Cooperia spp. and 10,000 Trichostrongylus axei infective larvae as a single dose. One group was treated with doramectin 6 days after infection while the remaining groups received saline or doramectin 27 days after infection. Given as a single subcutaneous injection behind the ear, doramectin at 200 microg/kg removed 99.9-100% of adult and larval stages of O. ostertagi, Cooperia spp. and T. axei when compared to infections established in untreated controls (p<0.001). No adverse reactions were observed following treatment in the doramectin-treated animals. No injection site lesions were found by palpation following treatment or by injection site examination at necropsy.  相似文献   

19.
Paraherquamide, an oxindole alkaloid metabolite of Penicillium paraherquei and Penicillium charlesii, was tested against the adult stages of nine common gastrointestinal and lung nematodes of calves at single, oral dosages of 0.5, 1.0, 2.0 or 4.0 mg kg-1. At dosages 1.0-4.0 mg kg-1 there was 95% or more removal of Haemonchus placei, Ostertagia ostertagi, Trichostrongylus axei, Trichostrongylus colubriformis, Cooperia oncophora, Nematodirus helvetianus, Oesophagostomum radiatum, and Dictyocaulus viviparus. Cooperia punctata, the dosage-limiting species, was virtually unaffected by any dosage except the highest, which produced an efficacy of 89%. The 0.5 mg kg-1 dosage was 95% or more efficacious against H. placei, O. ostertagi, C. oncophora, and D. viviparus, but weaknesses were evident against the other five species. No adverse reaction was observe in any calf.  相似文献   

20.
A study was conducted to determine the therapeutic efficacy of 1% doramectin injected subcutaneously at 200 microg/kg into cattle harbouring naturally acquired infections of inhibited Ostertagia ostertagi larvae. Sixteen yearling Friesian bulls, grazed without anthelmintic treatment throughout the autumn-winter, were selected on the basis of similar body weights and serum pepsinogen activities. After removal from pasture on day -23 they were weighed and randomly assigned to two treatment groups on the basis of this weight. On day 0, one group was given saline (1 ml/50 kg) while the second was treated with doramectin (200 microg/kg). Both treatments were given by subcutaneous injection. All stock were slaughtered 14-15 days after treatment. Moderate to high levels of adult O. ostertagi and Trichostrongylus axei and early and late 4th larval stages of O. ostertagi were recovered from saline-treated calves at necropsy. Doramectin was highly effective in eliminating all stages of O. ostertagi (99.9%; p<0.0001) and T. axei (100%; p<0.0001). No evidence of lesions were detected at the injection sites at necropsy. These results confirm that doramectin is an extremely effective broad-spectrum avermectin anthelmintic with efficacy against inhibited as well as maturing larval and adult forms of O. ostertagi.  相似文献   

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