Efficacy of moxidectin long-acting injectable formulation (1mg/kg bodyweight) against first instar larvae of Oestrus ovis in naturally infected sheep (original) (raw)
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Veterinary Parasitology, 2012
Cydectin(®) 2% LA Solution for Injection for Sheep (Pfizer Animal Health) is a long-acting (LA) formulation of moxidectin for the treatment and prevention of mixed infections of gastro-intestinal nematodes, respiratory nematodes and certain arthropod parasites in sheep. To evaluate the duration of persistent efficacy against nasal bots (Oestrus ovis), a natural exposure study was conducted in Spain during the summer of 2011. One hundred and twenty nasal bot-free, Rasa Aragonesa sheep were randomly allocated to eight groups of 15 animals each. On Day 0, four groups were treated at the recommended dose rate of 1 mg moxidectin/kg bodyweight. Four groups remained untreated as negative controls. All animals were held in nasal bot-proof housing except for exposure to natural challenge when one group of treated sheep and one of group of control animals were transferred to a local pasture at either 0-20, 20-40, 40-60, or 60-80 days after treatment. Following challenge, sheep were scored for clinical signs of bot infestation, necropsied and the heads sectioned for larval recovery. Nasal bot larvae were retrieved from 7 to 11 control sheep following each exposure period indicating that adult bots were active throughout the study. In the first challenge up to 20 days after treatment, when sheep were slaughtered immediately after exposure, the majority of larvae were first instar (L1) and only 3 of the 15 control sheep were infested with second instars (L2). There was 100% efficacy against L2 and 38.1% reduction in the number of live L1 in the treated sheep but mean counts were not significantly different between treatment and control groups (P ≥ 0.05). For the subsequent exposure periods 20-80 days after treatment (necropsies 7-9 days after challenge), 6-10 sheep were infested with L1 and 9-11 control sheep were infested with L2 and third instars (L3). There was negligible efficacy against L1, but treatment with moxidectin resulted in 100% control of L2 and L3. These results are consistent with the biology of nasal bots and control with a systemic agent, as the slower growing L1 have limited feeding and are therefore less susceptible to systemic parasiticides. The study demonstrated that the persistent efficacy of this long-acting injectable formulation of moxidectin protects against the development of active O. ovis infestations for at least 80 days after treatment.
Treatment of small lungworm infestation in sheep by using moxidectin
Veterinary Parasitology, 2004
The use of moxidectin (MXD) in the treatment of small lungworm infestation (Cystocaulus ocreatus, Muellerius capillaris, Neostrongylus linearis and Protostronglylus rufescens) in sheep, was evaluated. Twenty-one sheep naturally infested with small lungworms, were divided into three groups (n = 7) and treated as follows: group A with moxidectin 1% injectable solution at a dose rate of 0.2 mg kg −1 bodyweight, group B with moxidectin 0.1% oral drench at a dose rate of 0.2 mg kg −1 bodyweight and group C being controls. Before treatment, mean faecal larval counts were 30.7, 21.1 and 26.7 lpg in group A, B and C, respectively; 14 days after treatment respective counts were 0.4, 2.3 and 63.0 lpg, (percentage reduction after moxidectin administration >96.0%); 60 days after treatment respective counts were 0.0, 0.0 and 26.4 lpg, (percentage reduction after moxidectin administration 100%). It is concluded that treatment of small lungworm infestation of sheep can be effected by using moxidectin.
Veterinary Parasitology, 2004
A study was conducted under a common protocol in Wisconsin and Wyoming, USA, to evaluate therapeutic and persistent efficacy of two long-acting injectable formulations of moxidectin against lice populations infesting cattle. At each site, 30 beef calves were blocked into groups of three based on naturally acquired Linognathus vituli populations, then randomly assigned to treatments within blocks. Treatments, injected subcutaneously into the proximal third of the ear on Day 0, included saline, a long-acting oil-based formulation containing 10% moxidectin given at the rate of 1 mg moxidectin/kg body weight (M10/1.0), or a long-acting oil-based formulation containing 15% moxidectin given at the rate of 0.75 mg moxidectin/kg b.w. (M15/0.75). Species of sucking and chewing lice were quantified on nine predilection sites before treatment, then 28, 63, 98, 133 and 168 days after treatment. During intervals between lice counts after Day 28, study animals from the three treatment groups were commingled for 32 days with two lice-free sentinels plus four to six seeder calves with infestations of both sucking and chewing lice. Following each 32-day commingling interval, seeder and sentinel animals were removed, and principal animals were sorted into pens by treatment. Lice were quantified on sentinel animals on the day of removal, and lice were quantified on principal study animals 3 days after removal of sentinel and seeders. Moxidectin was generally not efficacious against Bovicola bovis in the injectable formulations tested, whereas Haematopinus eurysternus infestations were inadequate to judge product effectiveness. Based on geometric means, both M15/0.75 and M10/1.0 provided statistically significant therapeutic efficacy against existing infestations of L. vituli and Solenopotes capillatus (100% efficacy on Day 28), and provided persistent protection against reinfestation with L. vituli and S. capillatus (efficacy >97%) for at least 133 days following treatment.
Preventive veterinary …, 2005
Bovine hypodermosis is a myiasis caused by Hypoderma bovis and Hypoderma lineatum (Diptera, Oestridae) larvae, which has a severe economic impact on the livestock industry. Though myiasis is widespread throughout Italy, no nationwide eradication program has ever been planned, unlike in other European Countries. With a view to setting up a national control program, a pilot study was carried out in Southern Italy on 9939 cattle bred in an area with a high prevalence of cattle hypodermosis, using moxidectin 0.5% pour-on (Cydectin 1 , Fort Dodge) and 1% injectable (Cydectin 1 , Fort Dodge) formulations. At the recommended dosage, moxidectin displayed efficacy levels of 99.9% in the pour-on and 100% in the injectable formulation, whereas the microdose (1 mg per head regardless of body weight) was less effective (65.7%). This trial contributed to a significant reduction in infestation rates in the study area and represented the first step through which a national program for eradicating warble fly infestation in Italy.
Veterinary Parasitology, 2004
The chemoprophylactic efficacy of a single dose of the 10% long acting (LA) injectable formulation of moxidectin on nematode infections in calves, was evaluated. Two similar groups of 11 female, first grazing season Holstein calves were turned out in early May on separate plots of a single, naturally infected pasture. Until 56 days post-treatment (pt), the percentage reduction in faecal egg output was 100%, remaining above 90% during the entire trial, except for day 126 pt. More than 90% of the larvae in the treated group were identified as Cooperia until 140 days after treatment and more than 70% during the rest of the trial, whereas in the control group Cooperia was the most abundant species until day 84 pt and Ostertagia from 126 days pt onwards. The reduction in faecal egg output in the treated group was reflected in the mean pepsinogen levels being below the pathogenic threshold at the end of the grazing season (1.8 units of tysrosine (U tyr)) and the absence of diarrhoea during the second half of the grazing season. In the control group pepsinogen levels remained high (mean: 5.5 U tyr) and prolonged diarrhoea occurred in the second half of the grazing season. Furthermore, the weight gain for the treated group at the end of the grazing season was 41.9 kg higher than for the control group. At necropsy, the reduction in O. ostertagi worm burden in the treated group was 97.5% compared to the control group, while the reduction in C. oncophora worm burden was 57%. An additional benefit of the long acting parasitological control, was reduced pasture contamination.
The influence of parasitism on the pharmacokinetics of moxidectin in lambs
Parasitology Research, 2004
Most pharmacokinetic studies on anthelmintic drugs have been performed on non-parasitized animals. However, it seems likely that the parasite burden could influence the deposition of such drugs. The pharmacokinetics of moxidectin administered orally and by subcutaneous injection was compared in lambs exposed to nematode infection and in parasite naive lambs. Plasma samples were analyzed for moxidectin over 40 days post-treatment. The main pharmacokinetic parameters calculated demonstrated a significant change in drug deposition in infected lambs when compared to controls. The area under the plasma concentration—time curve was decreased 54% and 46% by infection in the subcutaneous and oral groups, respectively. There was also a major decrease in the mean residence time in parasitized lambs. In parallel, the clearance of the drug was increased by infection. Thus, parasite infection dramatically influences the disposition of moxidectin in lambs. These results may contribute to determining a therapeutic strategy adapted to heavily infested animals.
Veterinary Parasitology, 2004
Trials were conducted in Arkansas, Idaho, Illinois and Wisconsin using a common protocol to evaluate effectiveness and safety of a long acting (LA), oil-based injectable formulation of moxidectin in beef cattle grazing spring and/or summer pastures. At each site, 150 cattle (steers and/or heifers) were blocked based on pretreatment fecal strongyle egg counts (EPG) and then randomly assigned to treatments within blocks. Presence of naturally acquired parasitic infections, confirmed by presence of parasite eggs in feces, was a prerequisite for study enrollment. Within each block of three animals, two received moxidectin LA injectable on day 0 at a dosing rate of 1.0 mg moxidectin/kg b.w. into the dorsal aspect of the proximal third of the ear, and one received a placebo control treatment. Cattle were weighed before treatment and on day 55 or 56 (55/56) after treatment. Fecal samples were also collected from 10 randomly selected blocks of animals at each site on days 14, 28 and 55/56 for EPG quantification. Average daily gain (ADG) was computed over the posttreatment period. Data pertaining to ADG and EPG were combined across sites and analyzed
Veterinary Parasitology, 1998
A total of 24 male and female equines of mixed breed, 10±20 months of age and naturally infected with internal parasites was utilized in a controlled test to evaluate the efficacy of a moxidectin 2% gel formulation at the dosage of 0.4 mg moxidectin per kg of live weight and an ivermectin 1.87% commercial paste formulation at the dosage 0.2 mg ivermectin per kg applied orally. Animals were allocated into three groups of eight horses each based on pre-treatment eggs per gram (EPG) counts and treatments were randomized among the groups. One group was kept as untreated controls. One animal in the moxidectin-treated group died before the end of the trial from a cause unrelated to treatment leaving a total of seven animals in this group. Fecal egg counts were performed three times post-treatment and the number of parasites remaining in each animal was determined. Statistical analyses using geometric means were performed at the 1% level of significance. Both moxidectin and ivermectin preparations reduced initial EPG from a mean of 1600 to 0 on Days 5, 7 and at the end of the trial on Day 14. Efficacy percentages of moxidectin and ivermectin against immature and adult nematodes were as follows: Trichostrongylus axei, Parascaris equorum, Strongylus edentatus, S. vulgaris, Triodontophorus spp. and Gyalocephalus capitatus, 100% for both products; Habronema muscae 99.5 and 99.6%, respectively, Strongyloides westeri, 100 and 99.2%, respectively; Oxyuris equi, 99.6 and 100%, respectively; small strongyles, 99.7% for both products. Of the latter, the most numerous were: Cylicocyclus insigne, Cylicostephanus longibursatus and Cyathostomum catinatum. No Gasterophilus nasalis were found in horses from either treated group, while two of eight control horses had infections with this Veterinary Parasitology 80 (1998) 29±36 0304-4017/98/$ ± see front matter # 1998 Elsevier Science B.V. All rights reserved. PII: S 0 3 0 4 -4 0 1 7 ( 9 8 ) 0 0 1 8 6 -1 parasite. Moxidectin showed greater efficacy (84.9%) than ivermectin (67.8%) against Strongylus vulgaris larvae found in the mesenteric artery aneurisms, but the difference was not statistically significant. Total parasite counts for both treated groups were significantly lower (p<0.01) than in the non-treated group. No significant differences were noted between moxidectin and ivermectin. Efficacy against the 30 nematode species found in this study was very evident for both products. As expected, neither moxidectin nor ivermectin was effective in controlling the tapeworm Anoplocephala perfoliata. No adverse reactions were observed during the experimental period. #
Small Ruminant Research, 2015
A field study was undertaken on three Swiss sheep farms (A, B, C) to evaluate the efficacy of a long-acting moxidectin formulation (Cydectin® 2% LA) against gastrointestinal nematodes (GIN). Naturally infected ewes (all three farms) and their winter-borne lambs (farms A and B) were allocated to two groups (MOX, CON). At day 0 ewes of the MOX-groups were treated with 1 mg moxidectin s.c. CON- and MOX-groups were grazed on separate pastures and were sampled for faeces and blood at 28-day intervals. Larval cultures demonstrated that Haemonchus contortus was the dominant GIN-species in ewes throughout the season. Over the entire observation period faecal egg count (FEC) of the MOX-ewes in farms A, B, C was 56, 84 and 87% less than the CON-ewes (p < 0.05). FEC of lambs grazing with MOX-ewes was reduced in farms A and B by 56% and 61%, respectively (p < 0.05), compared with the respective CON-groups. None of these lambs received anthelmintic treatment during the experiment. Therefor...