RESUMEN
A series of 10 dose confirmation studies was conducted to evaluate the persistent activity of an extended-release injectable (ERI) formulation of eprinomectin against single point challenge infections of gastrointestinal and pulmonary nematodes of cattle. The formulation, selected based on the optimal combination of high nematode efficacy, appropriate plasma profile, and satisfactory tissue residue levels, includes 5% poly(D,L-lactide-co-glycolic)acid (PLGA) and is designed to deliver eprinomectin at a dose of 1.0mg/kg bodyweight. Individual studies, included 16-30 cattle blocked based on pre-treatment bodyweight and randomly allocated to treatment with either ERI vehicle or saline (control), or the selected Eprinomectin ERI formulation. Treatments were administered once at a dose volume of 1 mL/50 kg bodyweight by subcutaneous injection in front of the shoulder. In each study, cattle were challenged with a combination of infective stages of gastrointestinal and/or pulmonary nematodes 100, 120 or 150 days after treatment and were processed for parasite recovery according to standard techniques 25-30 days after challenge. Based on parasite counts, Eprinomectin ERI (1mg eprinomectin/kg bodyweight) provided >90% efficacy (p<0.05) against challenge with Cooperia oncophora and Cooperia surnabada at 100 days after treatment; against challenge with Ostertagia ostertagi, Ostertagia lyrata, Ostertagia leptospicularis, Ostertagia circumcincta, Ostertagia trifurcata, Trichostrongylus axei, and Cooperia punctata at 120 days after treatment; and against challenge with Haemonchus contortus, Bunostomum phlebotomum, Oesophagostomum radiatum and Dictyocaulus viviparus at 150 days after treatment. Results of a study to evaluate eprinomectin plasma levels in cattle treated with the Eprinomectin ERI formulation reveal a characteristic second plasma concentration peak and a profile commensurate with the duration of efficacy. These results confirm that the Eprinomectin ERI formulation can provide high levels of parasite control against a range of nematodes of cattle for up to 5 months following a single treatment.
Asunto(s)
Antinematodos/uso terapéutico , Enfermedades de los Bovinos/tratamiento farmacológico , Ivermectina/análogos & derivados , Infecciones por Nematodos/veterinaria , Animales , Antinematodos/sangre , Antinematodos/farmacocinética , Bovinos , Femenino , Inyecciones , Ivermectina/sangre , Ivermectina/farmacocinética , Ivermectina/uso terapéutico , Masculino , Nematodos/fisiología , Infecciones por Nematodos/tratamiento farmacológico , Distribución Aleatoria , Factores de TiempoRESUMEN
The efficacy of eprinomectin in an extended-release injection (ERI) formulation was evaluated against infections with third-stage larvae or eggs of gastrointestinal and pulmonary nematodes in cattle under 120-day natural challenge conditions in a series of five studies conducted in the USA (three studies) and in Europe (two studies). For each study, 30 nematode-free (four studies) or 30 cattle harboring naturally acquired nematode infections (one study) were included. The cattle were of various breeds or crosses, weighed 107.5-273 kg prior to treatment and aged approximately 4-11 months. For each study, animals were blocked based on pre-treatment bodyweight and then randomly allocated to treatment: ERI vehicle (control) at 1 mL/50 kg bodyweight or Eprinomectin 5% (w/v) ERI at 1 mL/50 kg bodyweight (1.0 mg eprinomectin/kg) for a total of 15 and 15 animals in each group. Treatments were administered once on Day 0 by subcutaneous injection in front of the shoulder. In each study, all animals grazed one naturally contaminated pasture for 120 days. At regular intervals during the studies, fecal samples from all cattle were examined for nematode egg and larval counts. In four studies pairs of tracer cattle were used to monitor pasture infectivity at 28-day intervals before and/or during the grazing period. All calves were weighed before turnout onto pasture and at regular intervals until housing on Day 120. For parasite recovery, all study animals were humanely euthanized 27-30 days after removal from pasture. Cattle treated with Eprinomectin ERI had significantly (p<0.05) fewer strongylid eggs (≤1 egg per gram; egg count reduction≥94%) than the control cattle and zero lungworm larvae at each post-treatment time point. At euthanasia, cattle treated with Eprinomectin ERI had significantly (p<0.05) fewer of the following nematodes than the ERI vehicle-treated (control) cattle with overall reduction of nematode counts by >92%: Dictyocaulus viviparus (adults and fourth-stage larvae (L4), Bunostomum phlebotomum, Cooperia curticei, Cooperia oncophora, Cooperia punctata, Cooperia surnabada, Cooperia spp. inhibited L4, Haemonchus contortus, Haemonchus placei, Haemonchus spp. inhibited L4, Nematodirus helvetianus, Nematodirus spp. inhibited L4, Oesophagostomum radiatum, Oesophagostomum spp. inhibited L4, Ostertagia leptospicularis, Ostertagia lyrata, Ostertagia ostertagi, Ostertagia spp. inhibited L4, Trichostrongylus axei, Trichostrongylus colubriformis, Trichostrongylus spp. inhibited L4, Trichuris discolor, and Trichuris ovis. Over the 120-day grazing period, Eprinomectin ERI-treated cattle gained between 4.8 kg and 31 kg more weight than the controls. This weight gain advantage was significant (p<0.05) in three studies. All animals accepted the treatment well. No adverse reaction to treatment was observed in any animal in any study.
Asunto(s)
Antinematodos/uso terapéutico , Enfermedades de los Bovinos/tratamiento farmacológico , Ivermectina/análogos & derivados , Infecciones por Nematodos/veterinaria , Animales , Antinematodos/administración & dosificación , Peso Corporal/fisiología , Bovinos , Enfermedades de los Bovinos/parasitología , Heces/parasitología , Femenino , Inyecciones , Ivermectina/administración & dosificación , Ivermectina/uso terapéutico , Masculino , Nematodos/fisiología , Infecciones por Nematodos/tratamiento farmacológico , Distribución AleatoriaRESUMEN
The therapeutic efficacy of eprinomectin in an extended-release injection (ERI) formulation was evaluated against induced infections of developing fourth-stage larval or adult gastrointestinal and pulmonary nematodes of cattle in a series of six studies under two identical protocols (three each for developing fourth-stage larvae or adults) conducted in the USA, Germany or the UK (two studies at each location, one per stage). Each study initially included 16 nematode-free cattle. The cattle were of various breeds or crosses, weighed 109-186.5 kg prior to treatment, and were approximately 4-7 months old. The animals were blocked based on pre-treatment bodyweight and then randomly allocated to treatment: eprinomectin ERI vehicle (control) at 1 mL/50 kg body weight or eprinomectin 5% ERI at 1 mL/50 kg bodyweight (1.0 mg eprinomectin/kg) for a total of eight and eight animals in each group. Treatments were administered once on Day 0 by subcutaneous injection in front of the shoulder. In each study, cattle were infected with a combination of infective third-stage larvae or eggs of gastrointestinal and pulmonary nematodes. Inoculation was scheduled so that the nematodes were expected to be fourth-stage larvae or adults at the time of treatment. For parasite recovery, all study animals were humanely euthanized and necropsied 14-15 (adult infections) or 21-22 days after treatment (developing fourth-stage larval infections). When compared with the vehicle-treated control counts, efficacy of eprinomectin ERI against developing fourth-stage larvae and adults was ≥98% (p<0.05) for the following nematodes: Dictyocaulus viviparus, Bunostomum phlebotomum, Cooperia curticei, C. oncophora, C. surnabada, C. punctata, Haemonchus contortus, H. placei, Nematodirus helvetianus, Oesophagostomum radiatum, Oes. venulosum, Ostertagia leptospicularis, O. ostertagi, O. circumcincta, O. pinnata, O. trifurcata (developing fourth-stage larval infections only), Strongyloides papillosus, Trichostrongylus axei, T. colubriformis, and Trichuris ovis (adult infections only). All animals accepted the treatment well. No adverse reaction to treatments was observed in any animal in any study.
Asunto(s)
Antinematodos/uso terapéutico , Enfermedades de los Bovinos/tratamiento farmacológico , Ivermectina/análogos & derivados , Infecciones por Nematodos/veterinaria , Animales , Antinematodos/administración & dosificación , Bovinos , Enfermedades de los Bovinos/parasitología , Femenino , Inyecciones , Ivermectina/administración & dosificación , Ivermectina/uso terapéutico , Larva , Masculino , Infecciones por Nematodos/tratamiento farmacológico , Infecciones por Nematodos/parasitología , Distribución Aleatoria , Resultado del TratamientoRESUMEN
In an experiment to determine the therapeutic efficacy of an ivermectin intraruminal controlled-release (CR) bolus, 14 mixed breed sheep of one lot were infested with Psoroptes ovis and subsequently divided into two groups of seven. In one of these groups each sheep received one ivermectin CR bolus appropriate to its weight, the other group remained as an untreated control. All mites were eliminated from the group receiving the bolus while the control group remained infested, the disease progressed, and all but one sheep required treatment for psoroptic mange before the end of the experimental period. A second lot of 14 sheep, free from P. ovis, were divided equally into two groups to determine the prophylactic efficacy of the ivermectin CR bolus. In one group, each sheep was given an ivermectin CR bolus according to body weight and the sheep in the other group received no medication and served as untreated controls. Twenty-one days later two sheep infested with psoroptic mange were introduced into each of the groups. These donor sheep were removed 10 days later. The group treated with the ivermectin CR bolus remained mange-free and did not harbour any mites. All of the sheep in the control group developed psoroptic mange and required treatment to control the infestation at the end of the experimental period. Sheep that received the ivermectin CR bolus had greater mean weight gains than the control groups in these experiments. The ivermectin CR bolus releases a minimum dose of 20 microg ivermectin kg/day for 100 days: this prolonged activity should prove a valuable asset for the treatment and control of psoroptic mange in sheep.
Asunto(s)
Insecticidas/uso terapéutico , Ivermectina/uso terapéutico , Infestaciones por Ácaros/veterinaria , Enfermedades de las Ovejas/tratamiento farmacológico , Animales , Preparaciones de Acción Retardada/uso terapéutico , Femenino , Insecticidas/administración & dosificación , Ivermectina/administración & dosificación , Masculino , Infestaciones por Ácaros/tratamiento farmacológico , Infestaciones por Ácaros/prevención & control , Distribución Aleatoria , Ovinos , Enfermedades de las Ovejas/parasitología , Enfermedades de las Ovejas/prevención & control , Aumento de PesoRESUMEN
The options for the treatment and control of sheep scab (psoroptic mange) have been increased in recent years through the introduction of the endectocides ivermectin, doramectin and moxidectin. Whilst therapeutic efficacy is good, the current injectable formulations offer limited protection against re-infestation with Psoroptes ovis. An intraruminal controlled-release formulation of ivermectin has been developed to provide therapeutic and prophylactic activity against a range of sensitive endo- and ecto-parasites of sheep for 100 days after administration. These ivermectin boluses are designed to release ivermectin at 20-40 microg/kg/day over 100 days and were developed for use in sheep of 20-90 kg bodyweight. Several controlled therapeutic and prophylactic trials against sheep scab have been conducted under a variety of protocols with such boluses in Europe and South America. The results of these studies indicate that the bolus provides 100% therapeutic efficacy against established P. ovis infestations and equivalent prophylactic efficacy against challenge infestations administered during the active life of the bolus.
Asunto(s)
Preparaciones de Acción Retardada/uso terapéutico , Insecticidas/uso terapéutico , Ivermectina/uso terapéutico , Infestaciones por Ácaros/veterinaria , Enfermedades de las Ovejas/prevención & control , Animales , Brasil , Alemania , Insecticidas/administración & dosificación , Insecticidas/normas , Irlanda , Ivermectina/administración & dosificación , Ivermectina/normas , Infestaciones por Ácaros/tratamiento farmacológico , Infestaciones por Ácaros/prevención & control , Ácaros/efectos de los fármacos , Distribución Aleatoria , Rumen/fisiología , Ovinos , Enfermedades de las Ovejas/tratamiento farmacológicoRESUMEN
OBJECTIVE: To evaluate efficacy of topically applied eprinomectin against inhibited early fourth-stage larvae (IL4) of Ostertagia spp in calves. ANIMALS: 4 groups (n = 6 [replicates]) for dose titration; 2 groups (n = 8 calves [replicates]) for dose confirmation. PROCEDURE: 2 dose titration studies-0, 125, 250, and 500 micrograms of eprinomectin/kg of body weight-Louisiana and Georgia- and 2 dose confirmation studies of selected therapeutic dosage (500 micrograms/kg) in Scotland and France. Monitor calves were used to determine inhibition percentage of Ostertagia IL4. Test calves were ranked by weight in replicates of 4 (titration trials) or 2 (confirmation trials) animals each, and within replicates, were randomly allocated to treatment groups. Drug treatments were done on day 0, and animals were euthanatized by replicate, with holding time between treatment and euthanasia varying among trials from 14 to 27 days. RESULTS: Observations indicated high efficacy (> 99%) of 500 micrograms of eprinomectin/kg in removal of Ostertagia IL4. Ostertagia and Cooperia were only genera common across sites, with efficacy of aforementioned dosage against adult and larval stages of both genera consistently high (> 99%). Results of 1 or both titration studies (500 micrograms/kg) indicated > 99 to 100% efficacy against adult Haemonchus placei, Trichostrongylus axei, T colubriformis, Bunostomum phlebotomum, Dictyocaulus viviparus, and Oesophagostomum radiatum. Lower efficacy values were observed at minimal (125 micrograms/kg) dosage. In France, 500 micrograms/kg was 85% effective against Trichostrongylus spp adults; however, numbers of control calves infected with Trichostrongylus spp and degree of infection were low. Adverse reactions were not evident. CONCLUSION: Eprinomectin given topically (500 micrograms) was highly effective against Ostertagia IL4 and other common nematodes of cattle.
Asunto(s)
Antihelmínticos/uso terapéutico , Enfermedades de los Bovinos/tratamiento farmacológico , Ostertagia/efectos de los fármacos , Ostertagiasis/veterinaria , Administración Tópica , Animales , Antihelmínticos/administración & dosificación , Bovinos , Enfermedades de los Bovinos/epidemiología , Enfermedades de los Bovinos/prevención & control , Relación Dosis-Respuesta a Droga , Femenino , Francia/epidemiología , Georgia/epidemiología , Larva/efectos de los fármacos , Larva/crecimiento & desarrollo , Larva/fisiología , Louisiana/epidemiología , Masculino , Ostertagia/crecimiento & desarrollo , Ostertagia/fisiología , Ostertagiasis/tratamiento farmacológico , Ostertagiasis/prevención & control , Escocia/epidemiología , Estaciones del AñoRESUMEN
One hundred and twenty four-month-old Hereford-Friesian cross heifers weighing from 88 to 130 kg were divided into two equal groups. One group acted as a control with each animal receiving one placebo bolus, the other animals received one prototype intraruminal sustained-release bolus designed to deliver approximately 8 mg ivermectin/day for 100 to 120 days. The boluses were administered the day before turnout in mid-May. Each group was grazed separately for 167 days on pastures contaminated with parasitic nematode larvae including the lungworm Dictyocaulus viviparus, and the gastrointestinal worms Ostertagia ostertagi, Cooperia oncophora and Nematodirus helvetianus. Parasitic disease did not occur in the ivermectin-bolus group, but the control group required anthelmintic treatment to control parasitic gastroenteritis at 111 and 154 days after turnout. Up to the 111th day after turnout, the peak mean nematode egg and larval counts per gram of faeces in controls was, respectively, 564 epg and 0.5 lpg. Based on faecal nematode egg counts and worm burdens in bolus-treated cattle removed from pasture at 119 days after turnout and bolus function studies, it was concluded that ivermectin delivery from the prototype bolus ceased between 95 and 98 days after administration. However, unlike the controls, the treated cattle did not develop parasitic gastroenteritis at any time. Their faecal nematode egg output was significantly (P < 0.01) lower (< 1 epg) compared to the controls and lungworm larval output zero during the functional life of the bolus. The faecal egg and larval outputs continued low until the end of the trial.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Enfermedades de los Bovinos/tratamiento farmacológico , Enfermedades de los Bovinos/parasitología , Ivermectina/uso terapéutico , Infecciones por Nematodos/veterinaria , Animales , Peso Corporal , Bovinos , Enfermedades de los Bovinos/fisiopatología , Preparaciones de Acción Retardada , Femenino , Ivermectina/administración & dosificación , Infecciones por Nematodos/tratamiento farmacológico , Estadística como Asunto , Reino UnidoRESUMEN
The parasiticide ivermectin has been administered to domestic livestock since 1981 to control internal and external parasites, including insects; some of the ivermectin is excreted unchanged in faeces. Concerns over the effects of ivermectin on dung-utilising insect populations and the potential for consequent persistence of dung on pastures have been raised. This paper presents the results of a study over two grazing seasons of the rate of decomposition of cattle dung pats exposed to normal environmental influences. The cattle had been treated at therapeutic levels with either an injectable or a sustained release bolus formulation of ivermectin. It was concluded that the rate of decomposition of the dung pats, the extent of their avoidance by the cows, the organic matter content of the soil and the populations of earthworms in the pastures were not affected by the use of ivermectin.
Asunto(s)
Heces , Ivermectina/farmacología , Animales , Biodegradación Ambiental/efectos de los fármacos , Bovinos , Enfermedades de los Bovinos/prevención & control , Monitoreo del Ambiente , Estudios de Evaluación como Asunto , Heces/microbiología , Heces/parasitología , Ivermectina/uso terapéutico , Enfermedades Parasitarias/prevención & control , Enfermedades Parasitarias en AnimalesRESUMEN
Eight controlled trials were conducted, using 96 cattle of European breeds, to evaluate the efficacy of abamectin against natural and artificially acquired infections of adult and fourth-stage larvae of all the economically important gastrointestinal nematodes and lungworms in Germany and the United Kingdom. Half the animals were treated on one occasion with abamectin at a dose of 200 micrograms/kg bodyweight given subcutaneously while the other half remained untreated. Worms were counted 14 or 21 days after treatment or 28 days after the last infection. The treatment was highly effective (> 99 to 100 per cent) (P < 0.05) at removing immature (L4) stages and adult worms of the following species: Ostertagia ostertagi (inhibited larvae included), Trichostrongylus axei, Haemonchus contortus, Bunostomum phlebotomum, Cooperia species Oesophagostomum radiatum and Dictyocaulus viviparus. Naturally acquired adult C surnabada and Trichuris discolor infections were also significantly (P < 0.05) reduced. For Nematodirus helvetianus the efficacy varied from 89.8 to > 99 per cent (P > 0.1 to < 0.01). Abamectin gave full protection against the gastrointestinal nematodes O ostertagi, H contortus, Cooperia species and O radiatum for at least seven days and against the lungworm D viviparus for at least 14 days after treatment.
Asunto(s)
Antihelmínticos/uso terapéutico , Enfermedades de los Bovinos/tratamiento farmacológico , Parasitosis Intestinales/veterinaria , Ivermectina/análogos & derivados , Infecciones por Nematodos/veterinaria , Animales , Bovinos , Enfermedades de los Bovinos/prevención & control , Infecciones por Dictyocaulus/tratamiento farmacológico , Infecciones por Dictyocaulus/prevención & control , Femenino , Parasitosis Intestinales/tratamiento farmacológico , Parasitosis Intestinales/prevención & control , Ivermectina/uso terapéutico , Masculino , Infecciones por Nematodos/tratamiento farmacológico , Infecciones por Nematodos/prevención & controlRESUMEN
Two trials involving a total of 36 Dorset horn lambs were conducted to assess the anthelmintic efficacy of ivermectin against experimental infections of benzimidazole-resistant strains of Haemonchus contortus and Ostertagia circumcincta. Two resistant strains of each of the two species were used and in each trial the lambs were allocated to three groups. One group was given 200 micrograms ivermectin/kg bodyweight orally, the second group was given 5 mg oxfendazole/kg bodyweight orally and the third group remained untreated as controls. Fourteen days after treatment the lambs were necropsied. Ivermectin was found to be more than 99 per cent to 100 per cent effective against all four benzimidazole-resistant strains, whereas oxfendazole was 78.6 per cent and 83.8 per cent effective against the H contortus strains, and 25.6 per cent and 39.8 per cent effective against the O circumcincta strains.
Asunto(s)
Bencimidazoles/farmacología , Haemonchus/efectos de los fármacos , Ivermectina/farmacología , Ostertagia/efectos de los fármacos , Animales , Resistencia a Medicamentos , Hemoncosis/tratamiento farmacológico , Hemoncosis/etiología , Masculino , Ostertagiasis/tratamiento farmacológico , Ostertagiasis/etiología , Recuento de Huevos de Parásitos/veterinaria , OvinosAsunto(s)
Babesiosis/parasitología , Gerbillinae , Enfermedades de los Roedores/parasitología , Animales , Babesia/crecimiento & desarrollo , Babesiosis/mortalidad , Sangre/parasitología , Temperatura Corporal , Eritrocitos/parasitología , Gerbillinae/parasitología , Tamaño de los Órganos , Enfermedades de los Roedores/mortalidadAsunto(s)
Fenómenos Biomecánicos , Placas Óseas , Huesos/fisiología , Animales , Radio (Anatomía) , Ovinos/fisiología , Cráneo , Estrés MecánicoAsunto(s)
Fenómenos Biomecánicos , Radio (Anatomía)/fisiología , Animales , Cabras , Métodos , Movimiento , Ovinos , Resistencia a la TracciónRESUMEN
Rosette strain gauges were attached to the cranial and caudal aspects of the proximal half of the radius in eight skeletally mature female sheep; The sheep's radius has a slight cranially convex curvature. During walking it was deformed so that the cranial surface was subjected to tension aligned along the bone's lon axis, and the caudal surface to compression similarly aligned. The compressive strain on the caudal aspect of the bone was consistently larger (X 1-9) than the tensile strain on the cranial aspect. The thickness of the cortex did not reflect this difference but in younger animals the process of osteonal remodelling seemed further advanced in the cortex which was customarily subject to the larger deformation. The relevance of these findings is discussed in relation to the technique of internal fixation and to our understanding of the basis of the mechanical adaptability of bone.