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1.
PLoS One ; 15(8): e0236143, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32790679

RESUMO

The focus of gastro-intestinal parasite control in the sheep industry is increasingly on finding a balance between maintaining productivity of the flock whilst minimising selection for anthelmintic resistance to preserve anthelmintic efficacy for the future. Periparturient ewes represent the major source of gastro-intestinal parasites for growing lambs and are therefore a priority for parasite control. This study examines the impact on ewe faecal egg counts (FECs), lamb FECs, lamb daily live weight gains (DLWGs) and pasture larval counts of treating groups of ewes two weeks prior to lambing with either, a long-acting moxidectin treatment, short-acting doramectin or control. Six groups of twenty ewes were allocated to individual paddocks, two groups allocated to each treatment, and weekly faecal sampling was performed throughout from the ewes and from six weeks after the start of lambing in the lambs. Treatment group was found to have a significant effect on both ewe FEC (p<0.001) and lamb FEC (p = 0.001) with the group receiving the long-acting anthelmintic having the lowest ewe and lamb FECs. There was no significant effect on the DLWGs of the lambs. Pasture larval counts at the end of the study period were lowest in the long-acting wormer treatment group. The use of long-acting moxidectin may be helpful as part of a parasite control programme by reducing the worm burdens of ewes and their lambs, decreasing the number of anthelmintic treatments required in that year and by reducing pasture contamination for those sheep which will graze the pasture in the next year. However, like all anthelmintics, its use should be judicious to avoid selection for resistance.


Assuntos
Criação de Animais Domésticos/métodos , Anti-Helmínticos/administração & dosagem , Infecções por Nematoides/veterinária , Doenças dos Ovinos/tratamento farmacológico , Ovinos/parasitologia , Animais , Anti-Helmínticos/farmacocinética , Fazendas , Fezes/parasitologia , Feminino , Meia-Vida , Ivermectina/administração & dosagem , Ivermectina/análogos & derivados , Ivermectina/farmacocinética , Larva , Macrolídeos/administração & dosagem , Macrolídeos/farmacocinética , Nematoides/isolamento & purificação , Infecções por Nematoides/diagnóstico , Infecções por Nematoides/tratamento farmacológico , Infecções por Nematoides/parasitologia , Contagem de Ovos de Parasitas/veterinária , Período Pós-Parto , Gravidez , Doenças dos Ovinos/diagnóstico , Doenças dos Ovinos/parasitologia
2.
Trop Anim Health Prod ; 52(5): 2213-2219, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32388661

RESUMO

Endoparasitic nematode infection could have negative impacts on performances of sheep and goats. However, supplementary protein and minerals can also affect nematodes. This paper reviews present information on the importance of protein and minerals supplementation as means to control nematode infection in small ruminants. Protein supplementation seems to improve host resilience by diverting metabolizable protein (MP) towards dealing with detrimental effects of the infection and thus improve production and reproductive performances of animal. A large body of evidence shows that supplementation of copper, iron, and zinc can also enhance host resistance against nematode infection as shown by decreased fecal egg count (FEC) and worm burdens. As such, protein and mineral supplementations can play a major role in sustainable control of parasitic nematode infection and thus reduce reliance on chemotherapic drugs.


Assuntos
Proteínas na Dieta/metabolismo , Doenças das Cabras/tratamento farmacológico , Minerais/metabolismo , Infecções por Nematoides/veterinária , Substâncias Protetoras/farmacologia , Doenças dos Ovinos/tratamento farmacológico , Ração Animal/análise , Animais , Dieta/veterinária , Proteínas na Dieta/administração & dosagem , Suplementos Nutricionais/análise , Doenças das Cabras/parasitologia , Cabras , Minerais/administração & dosagem , Infecções por Nematoides/tratamento farmacológico , Infecções por Nematoides/parasitologia , Ovinos , Doenças dos Ovinos/parasitologia , Carneiro Doméstico
3.
Rev Bras Parasitol Vet ; 29(1): e015819, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32236331

RESUMO

An evaluation was made of the effect of anthelmintic treatments on the performance of Simmental X Nellore crossbred calves before and after weaning. To this end, the calves were divided into three groups: (1) treated monthly with a low efficacy anthelmintic drug, ivermectin; (2) treated monthly with a highly effective anthelmintic drug, albendazole; and (3) untreated control group. All the groups in this experiment showed an average fecal egg count of less than 400 eggs per gram (EPG), and no clinical signs of parasitic gastroenteritis. The blood variables were within the normal range and no calf presented anemia. In most of the samplings, mean EPGs were significantly lower (P<0.05) in the group treated with albendazole. The calves received dietary supplementation before and after weaning, which enabled them to gain weight in every month of the experiment and reach a body weight of about 250 kg on the last sampling date, before turning one year old. The anthelmintic treatments did not affect body weight gain, leading to the conclusion that, when fed with suitable dietary supplements, Simmental X Nellore crossbred calves are not affected by gastrointestinal nematode parasites acquired by grazing.


Assuntos
Albendazol/administração & dosagem , Anti-Helmínticos/administração & dosagem , Doenças dos Bovinos/tratamento farmacológico , Gastroenteropatias/veterinária , Ivermectina/administração & dosagem , Infecções por Nematoides/veterinária , Animais , Bovinos , Fezes/parasitologia , Feminino , Gastroenteropatias/tratamento farmacológico , Gastroenteropatias/parasitologia , Masculino , Infecções por Nematoides/tratamento farmacológico , Infecções por Nematoides/parasitologia , Contagem de Ovos de Parasitas/veterinária
4.
Adv Parasitol ; 108: 1-45, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32291083

RESUMO

Parasitic roundworms (nematodes) cause substantial morbidity and mortality in animals worldwide. Anthelmintic treatment is central to controlling these worms, but widespread resistance to most of the commercially available anthelmintics for veterinary and agricultural use is compromising control, such that there is an urgency to discover new and effective drugs. The purpose of this article is to review information on parasitic nematodes, the treatment and control of parasitic nematode infections and aspects of discovering new anthelmintics in the context of anthelmintic resistance problems, and then to discuss some progress that our group has made in identifying selected compounds with activity against nematodes. The focus of our recent work has been on discovering new chemical entities and known drugs with anthelmintic activities against Haemonchus contortus as well as other socioeconomically important parasitic nematodes for subsequent development. Using whole worm-based phenotypic assays, we have been screening compound collections obtained via product-development-partnerships and/or collaborators, and active compounds have been assessed for their potential as anthelmintic candidates. Following the screening of 15,333 chemicals from five distinct compound collections against H. contortus, we have discovered one new chemical entity (designated SN00797439), two human kinase inhibitors (SNS-032 and AG-1295), 14 tetrahydroquinoxaline analogues, one insecticide (tolfenpyrad) and two tolfenpyrad (pyrazole-5-carboxamide) derivatives (a-15 and a-17) with anthelmintic activity in vitro. Some of these 20 'hit' compounds have selectivity against H. contortus in vitro when compared to particular human cell lines. In our opinion, some of these compounds could represent starting points for 'lead' development. Accordingly, the next research steps to be pursued include: (i) chemical optimisation of representative chemicals via structure-activity relationship (SAR) evaluations; (ii) assessment of the breadth of spectrum of anthelmintic activity on a range of other parasitic nematodes, such as strongyloids, ascaridoids, enoplids and filarioids; (iii) detailed investigations of the absorption, distribution, metabolism, excretion and toxicity (ADMET) of optimised chemicals with broad nematocidal or nematostatic activity; and (iv) establishment of the modes of action of lead candidates.


Assuntos
Anti-Helmínticos/farmacologia , Descoberta de Drogas/tendências , Infecções por Nematoides/tratamento farmacológico , Animais , Humanos , Nematoides/efeitos dos fármacos
5.
Parasit Vectors ; 13(1): 70, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-32113470

RESUMO

BACKGROUND: Gastrointestinal nematodes are parasites that commonly infect dogs, and infections can be subclinical or may cause considerable clinical disease. Some species are zoonotic and may also cause clinical disease in humans. Year-round treatment of dogs is recommended to eliminate existing infections, which also indirectly reduces the potential for subsequent human exposure to zoonotic species. Here we present two studies that evaluated the safety and efficacy of a novel chewable oral tablet containing sarolaner, moxidectin and pyrantel against gastrointestinal nematode infections in dogs presented as veterinary patients in Europe and the USA. METHODS: Dogs naturally infected with Toxocara canis, Toxascaris leonina, Ancylostoma caninum and/or Uncinaria stenocephala were enrolled in the European study, and dogs naturally infected with T. canis were enrolled in the USA study. The animals were treated once orally with Simparica Trio™ tablets to provide 1.2-2.4 mg/kg sarolaner, 24-48 µg/kg moxidectin and 5-10 mg/kg pyrantel (as pamoate salt) or with a commercially available product according to the label directions as positive control. Efficacy was based on the post-treatment reduction in geometric mean egg counts (per gram feces) 7 or 10 days after treatment compared to pre-treatment egg counts. RESULTS: Simparica Trio™ was well tolerated in both studies. In the European study, geometric mean egg counts for T. canis, T. leonina, A. caninum and U. stenocephala were reduced by ≥ 98.3% in the Simparica Trio™ group and by ≥ 97.4% in the afoxolaner + milbemycin oxime group. In the USA study, geometric mean egg counts for T. canis were reduced by 99.2% in the Simparica Trio™ group and by 98.6% in the ivermectin + pyrantel group. In the USA study, 48 and 10 dogs in the Simparica Trio™ and the ivermectin + pyrantel group, respectively, were co-infected with A. caninum and the reduction in the post-treatment mean fecal egg counts were 98.6% and 74.7%, respectively. CONCLUSIONS: A single oral administration of Simparica Trio™ chewable tablets was well tolerated and was effective in the treatment of dogs with naturally occurring gastrointestinal nematode infections presented as veterinary patients in Europe and the USA.


Assuntos
Antinematódeos/administração & dosagem , Doenças do Cão/tratamento farmacológico , Enteropatias Parasitárias/veterinária , Nematoides/efeitos dos fármacos , Infecções por Nematoides/veterinária , Administração Oral , Animais , Azetidinas/administração & dosagem , Cães , Combinação de Medicamentos , Europa (Continente) , Feminino , Enteropatias Parasitárias/tratamento farmacológico , Macrolídeos/administração & dosagem , Masculino , Nematoides/classificação , Infecções por Nematoides/tratamento farmacológico , Contagem de Ovos de Parasitas , Pirantel/administração & dosagem , Compostos de Espiro/administração & dosagem , Resultado do Tratamento , Estados Unidos
6.
Vet Clin North Am Food Anim Pract ; 36(1): 17-30, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32029182

RESUMO

Control of gastrointestinal nematodes has been based on anthelmintics. However, this strategy is unsustainable owing to anthelmintic resistance. Parasitic nematodes have biologic and genetic features that favor the development of drug resistance, making the emergence of resistant nematodes inevitable. The rate of resistance development is affected controllable factors. There is a need to change the paradigm of how gastrointestinal nematodes are controlled to decrease the rate at which resistance develops. This article reviews the biology and prevalence of anthelmintic resistance, and provides recommendations for diagnosing resistance and for strategies that should be implemented to reduce the development of resistance.


Assuntos
Anti-Helmínticos/farmacologia , Doenças dos Bovinos/tratamento farmacológico , Doenças das Cabras/tratamento farmacológico , Gado/parasitologia , Infecções por Nematoides/veterinária , Doenças dos Ovinos/tratamento farmacológico , Animais , Bovinos , Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/parasitologia , Resistência a Medicamentos , Doenças das Cabras/epidemiologia , Doenças das Cabras/parasitologia , Cabras , Nematoides/isolamento & purificação , Infecções por Nematoides/tratamento farmacológico , Infecções por Nematoides/epidemiologia , Prevalência , Ovinos , Doenças dos Ovinos/epidemiologia , Doenças dos Ovinos/parasitologia
7.
Vet Clin North Am Food Anim Pract ; 36(1): 59-71, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32029189

RESUMO

Parasite species infecting cattle throughout northern North American are generally the same as those found throughout North America. Throughout Canada, cattle are primarily infected with Ostertagia ostertagi and Cooperia oncophora, whose larvae survive cold winters within soil of pastures. Overwintering larvae of these species maintain a temporary population of refugia available in spring to grazing cattle. Cattle from northern United States are also infected with Cooperia punctata and Haemonchus placei, whose larvae cannot survive cold winters within pastures. Anthelmintics with persistent activity are used during spring to recover some of these losses; however, anthelmintic resistance limits effectiveness of this strategy.


Assuntos
Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/prevenção & controle , Infecções por Nematoides/veterinária , Animais , Anti-Helmínticos/administração & dosagem , Bovinos , Doenças dos Bovinos/tratamento farmacológico , Doenças dos Bovinos/parasitologia , Indústria de Laticínios/métodos , Feminino , Trato Gastrointestinal/parasitologia , Nematoides/isolamento & purificação , Infecções por Nematoides/tratamento farmacológico , Infecções por Nematoides/epidemiologia , Infecções por Nematoides/prevenção & controle , América do Norte/epidemiologia , Estações do Ano
8.
Vet Clin North Am Food Anim Pract ; 36(1): 73-87, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32029190

RESUMO

Strongylid gastrointestinal nematodes are an important cause of disease and economic loss in small ruminants. These parasites are important in most of the United States, with the bloodsucking parasite Haemonchus contortus being the predominant species of concern. Sheep and goats are infected while grazing, and the biology of infective larvae on pastures is important in the design of parasite management programs. Widespread resistance to anthelmintics requires strategies designed to preserve remaining drug activity; these include combination treatments with multiple classes of anthelmintics and targeted treatments.


Assuntos
Doenças das Cabras/epidemiologia , Doenças das Cabras/prevenção & controle , Infecções por Nematoides/veterinária , Doenças dos Ovinos/epidemiologia , Doenças dos Ovinos/prevenção & controle , Animais , Anti-Helmínticos/administração & dosagem , Trato Gastrointestinal/parasitologia , Doenças das Cabras/tratamento farmacológico , Doenças das Cabras/parasitologia , Cabras , Nematoides/isolamento & purificação , Infecções por Nematoides/tratamento farmacológico , Infecções por Nematoides/epidemiologia , Infecções por Nematoides/prevenção & controle , Ovinos , Doenças dos Ovinos/tratamento farmacológico , Doenças dos Ovinos/parasitologia
9.
Rev Bras Parasitol Vet ; 29(1): e013119, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32049139

RESUMO

The objective of this study was to evaluate the efficacy of carvacryl acetate (CVA) and nanoencapsulated CVA (nCVA) on gastrointestinal nematodes of sheep. The CVA was nanoencapsulated with chitosan/gum arabic and the efficacy of nanoencapsulation (EE), yield, zeta potential, nanoparticle morphology and release kinetics at pH 3 and 8 were analyzed. Acute and subchronic toxicity were evaluated in rodents and reduction of egg counts in the faeces (FECRT) of sheep. The sheep were divided into four groups (n = 10): G1, 250 mg/kg CVA; G2, 250 mg/kg nCVA; G3, polymer matrix and G4: 2.5 mg/kg monepantel. EE and nCVA yield were 65% and 57%, respectively. The morphology of the nanoparticles was spherical, size (810.6±286.7 nm), zeta potential in pH 3.2 (+18.3 mV) and the 50% release of CVA at pHs 3 and 8 occurred at 200 and 10 h, respectively. nCVA showed LD50 of 2,609 mg/kg. CVA, nCVA and monepantel reduced the number of eggs per gram of faeces (epg) by 57.7%, 51.1% and 97.7%, respectively. The epg of sheep treated with CVA and nCVA did not differ from the negative control (P>0.05). Nanoencapsulation reduced the toxicity of CVA; however, nCVA and CVA presented similar results in the FECRT.


Assuntos
Anti-Helmínticos/administração & dosagem , Trato Gastrointestinal/parasitologia , Monoterpenos/administração & dosagem , Nanocápsulas/administração & dosagem , Nematoides/efeitos dos fármacos , Infecções por Nematoides/tratamento farmacológico , Doenças dos Ovinos/tratamento farmacológico , Animais , Anti-Helmínticos/toxicidade , Fezes/parasitologia , Feminino , Camundongos , Monoterpenos/toxicidade , Nanocápsulas/toxicidade , Nematoides/classificação , Nematoides/isolamento & purificação , Infecções por Nematoides/parasitologia , Contagem de Ovos de Parasitas , Testes de Sensibilidade Parasitária , Reação em Cadeia da Polimerase em Tempo Real , Roedores , Ovinos , Doenças dos Ovinos/parasitologia , Testes de Toxicidade
10.
J Helminthol ; 94: e125, 2020 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-32036795

RESUMO

Our objective was to measure the efficacy of ivermectin (IVM) and benzimidazoles (BZ, i.e. fenbendazole and albendazole) in 15 cattle farms in western France and southern Italy. A total of 11 groups were treated with IVM and 11 with BZ. Efficacy was assessed by calculating the percentage of faecal egg count reduction (%FECR) using the pre- and post-treatment arithmetic means. Anthelmintic resistance was considered to be present when the %FECR was <95% and the lower limit of the 95% confidence interval <90%. For IVM, the percentages of FECR ranged from 73% to 100%. Lack of efficacy to IVM was detected in two farms out of four in France, but was not detected in any of the seven farms in Italy. For BZ, the percentages of FECR ranged from 95% to 100%. No case of BZ resistance was detected in the five farms in France and the six farms in Italy.


Assuntos
Anti-Helmínticos/uso terapêutico , Doenças dos Bovinos/tratamento farmacológico , Gastroenteropatias/veterinária , Nematoides/efeitos dos fármacos , Infecções por Nematoides/veterinária , Animais , Benzimidazóis/uso terapêutico , Bovinos , Doenças dos Bovinos/parasitologia , Fazendas , Fezes/parasitologia , França , Gastroenteropatias/tratamento farmacológico , Gastroenteropatias/parasitologia , Trato Gastrointestinal/parasitologia , Itália , Ivermectina/uso terapêutico , Infecções por Nematoides/tratamento farmacológico , Contagem de Ovos de Parasitas
11.
J Helminthol ; 94: e115, 2020 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-31931890

RESUMO

Drug resistance to helminth parasites is one of the most serious problems to threaten the livestock industry. The problem also poses a major threat to public health. Therefore, novel and safe agents should urgently be investigated to control parasitic infections. The current study was conducted to evaluate the possible antiparasitic effects of zinc oxide nanoparticles (ZnO-NPs) on one of the most prevalent gastrointestinal nematodes, Teladorsagia circumcincta. The worms were incubated with various concentrations of ZnO-NPs: 1, 4, 8, 12 and 16 ppm for 24 hours. Mobility and mortality of the parasites were recorded at four-hour intervals. At the endpoint, several biomarkers of oxidative/nitrosative stress, including superoxide dismutase, glutathione peroxidase and catalase, as well as lipid peroxidation, protein carbonylation, total antioxidant status, nitric oxide contents and DNA damage, were measured in the homogenized samples. ZnO-NPs showed significant anthelminthic effects, depending on time and concentration. Furthermore, the nanoparticle induced severe oxidative/nitrosative stress and DNA damage. ZnO-NPs could be considered as a novel and potent anthelminthic agent.


Assuntos
Anti-Helmínticos/farmacologia , Infecções por Nematoides/veterinária , Óxido de Zinco/farmacologia , Animais , Biomarcadores Farmacológicos , Dano ao DNA , Gado/parasitologia , Nanopartículas/parasitologia , Infecções por Nematoides/tratamento farmacológico , Infecções por Nematoides/parasitologia , Estresse Oxidativo
13.
Vet Parasitol ; 277: 109018, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31896020

RESUMO

Control of sheep gastrointestinal nematode (GIN) infections mostly relies on the use of anthelmintics. Refugia-based control strategies as targeted selective treatments (TST) can delay anthelmintic resistance development, but the optimal decision criteria for selecting individuals to be treated in subclinical infection scenarios remain unclear. The present study aimed to evaluate the suitability of body condition score (BCS) and faecal egg counts (FEC) as treatment indicators and to determine their optimized threshold values for treatment in TST by determining the relationships of BCS, FEC and anthelmintic treatment with several productive parameters in pre-mating and pre-partum periods at an individual level. Deworming in pre-mating period increased BCS gain, but its magnitude was directly associated with strongyle FEC before treatment. Deworming also increased fertility in ewes with BCS < 2.75 and the proportion of lambing ewes that got pregnant during the first ovulation cycle. Nevertheless, treatment did not yield productive benefits in ewes with higher BCS values. On the other hand, deworming in the pre-partum lowered lamb peri-partum mortality and increased lamb weight at birth and the growth of lambs during lactation, especially in lambs born from ewes with strongyle FEC > 400 epg before treatment. These results showed that FEC and especially BCS can be potential decision criteria for the implementation of TST in these types of scenarios. The TST scheme derived from the present results on the control of GIN infections should include anthelmintic treatment of ewes with BCS lower than ≈ 3 approximately five weeks before mating and lambing. In the pre-lambing period, treatment may be unnecessary if flock mean strongyle FEC is lower than ≈ 200 epg, as the proportion of ewes with individual FEC > 400 epg would be very low. The results suggest that implementation of this TST scheme would provide benefits, such as the improvement of productivity, a rational management of parasites in refugia, and preservation of future efficacy of anthelmintics, in comparison to traditional deworming schemes.


Assuntos
Gastroenteropatias/veterinária , Infecções por Nematoides/veterinária , Doenças dos Ovinos/tratamento farmacológico , Doenças dos Ovinos/prevenção & controle , Animais , Infecções Assintomáticas , Feminino , Gastroenteropatias/tratamento farmacológico , Gastroenteropatias/prevenção & controle , Infecções por Nematoides/tratamento farmacológico , Infecções por Nematoides/prevenção & controle , Gravidez , Ovinos
14.
Trop Anim Health Prod ; 52(3): 1365-1374, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31758387

RESUMO

The aim of this study was to compare the economic revenue related to the use of low- or high-efficacy anthelmintic drugs within suppressive or strategic schemes of treatment in growing heifers. Heifers raised in a semi-intensive grazing system in southern Brazil were used. Levamisole and ivermectin were selected as the high- and the low-efficacy drugs, respectively, based on a previous efficacy test. Subsequently, these drugs were used within strategic (Strat; four times per year) or suppressive (Supp; once a month) treatment regimens in the heifers, and their liveweight and eggs per gram of feces counts were monthly evaluated during a 13-month period. The total costs of the treatments and their cost-benefit ratio in regard to liveweight gain were calculated. Final mean liveweight gains (kg) observed were 126.7 (Strat-Low), 133.6 (Supp-Low), 141.3 (Strat-High), 142.9 (Supp-High), and 125.8 (Control). Treatments with a high-efficacy drug resulted in monetary gains of US$ 19.56 (Strat-High) and US$ 14.98 (Supp-High), but Supp-Low and Strat-Low treatments caused economic losses. Total cost of the efficacy test (US$ 374.79) could be paid by the additional liveweight gain of 20 heifers from the Strat-High group. These results showed that it would be preferable not to treat the heifers against GIN if compared with treating them with a low-efficacy drug. In addition, we showed that the use of four treatments per year with a high-efficacy drug-selected by efficacy test-resulted in a profitable management to control GIN in growing heifers raised in a semi-intensive gazing system in southern Brazil.


Assuntos
Anti-Helmínticos/economia , Doenças dos Bovinos/economia , Ivermectina/economia , Levamisol/economia , Infecções por Nematoides/veterinária , Animais , Anti-Helmínticos/uso terapêutico , Brasil , Bovinos , Doenças dos Bovinos/tratamento farmacológico , Fezes/parasitologia , Feminino , Ivermectina/uso terapêutico , Levamisol/uso terapêutico , Masculino , Infecções por Nematoides/tratamento farmacológico , Infecções por Nematoides/economia , Óvulo , Contagem de Ovos de Parasitas/veterinária
15.
N Z Vet J ; 68(3): 187-192, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31778612

RESUMO

ABSTRACTAims: The main goal of the current study was to evaluate, on a commercial beef cattle farm, the impact of infection with gastrointestinal nematodes resistant to both ivermectin (IVM) and moxidectin (MXD) on the productivity of calves.Methods: Male Aberdeen Angus calves, aged 9-11 months, with faecal nematode egg counts (FEC) ≥200 epg and body weight ≥190 kg, were allocated to two herds. Herd A (n = 90) grazed a maize-winter forage crop rotation and Herd B (n = 90) grazed a 2-year-old Agropyrum pasture. On Day 0 in each herd, calves were randomly allocated into five groups (n = 18), which were treated with 0.2 mg/kg IVM; 0.2 mg/kg MXD; 3.75 mg/kg ricobendazole (RBZ), both IVM and RBZ, or remained untreated. Faecal samples collected on Days -1 and 19 were used to determine the percentage reduction in FEC, and genera of the nematodes were determined by the identification of the third-stage larvae recovered from faecal cultures. Total weight gain was determined from body weights recorded on Days -1 and 91.Results: Overall mean reduction in FEC was 42% for IVM, 67% for MXD, 97% for RBZ and 99% for IVM + RBZ. The reduction in FEC for Cooperia spp. was ≤78% for IVM and MXD, and for Haemonchus spp. was 0 and 36% for IVM and MXD, respectively, confirming the presence of parasites resistant to both anthelmintics. Only IVM + RBZ treatment resulted in 100% efficacy against Haemonchus spp. The overall estimated mean total weight gain for calves treated with IVM was 15.7 (95% CI = 11.9-19.7) kg and for calves treated with IVM + RBZ was 28.8 (95% CI = 25-32.5) kg (p < 0.001). Mean total weight gain for calves treated with MXD was 23.5 (95% CI = 19.7-27.2) kg.Conclusions and clinical relevance: In calves naturally infected with resistant nematodes, under the production system assessed here, weight gains were lower in calves treated with anthelmintics that were moderately or highly ineffective compared to those treated with highly effective anthelmintics. These results demonstrate to farmers and veterinarians the importance of a sustainable and effective nematode control under field conditions.


Assuntos
Albendazol/análogos & derivados , Antiparasitários/farmacologia , Doenças dos Bovinos/tratamento farmacológico , Ivermectina/farmacologia , Macrolídeos/farmacologia , Infecções por Nematoides/veterinária , Albendazol/farmacologia , Animais , Anti-Helmínticos/farmacologia , Antinematódeos/farmacologia , Argentina , Peso Corporal/efeitos dos fármacos , Bovinos , Doenças dos Bovinos/parasitologia , Doenças dos Bovinos/fisiopatologia , Resistência a Múltiplos Medicamentos , Quimioterapia Combinada/veterinária , Masculino , Infecções por Nematoides/tratamento farmacológico , Infecções por Nematoides/fisiopatologia , Contagem de Ovos de Parasitas/veterinária , Carne Vermelha
16.
Trop Anim Health Prod ; 52(4): 1699-1705, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31865537

RESUMO

Co-infections caused by trypanosomes and gastro-intestinal nematodes (GINs) compromise cattle productivity and their control requires a holistic approach. The effectiveness of trypanocides and anthelmintics is compromised by increasing resistance. Use of combined chemotherapeutic products for synergy, mainly practiced in human medicine, is gaining importance in livestock. A trial to evaluate efficacy of VERYL®, containing diminazene diaceturate (3.5 mg/kg body weight) and levamisole chloride (5 mg/kg body weight) for the control of GINs in cattle, was conducted at KALRO-VSRI Muguga, Kenya, between June and August 2016. Thirty-eight cattle aged between 6 and 12 months, naturally infected with GINs, were randomly allocated into two groups; a treatment group received VERYL® intra-muscularly at 10 mL/100 kg bwt and a control group which received Veriben® (Diminazene aceturate) at 3.5 mg/kg bwt. Faecal egg counts (FECs), coproculture, packed cell volume (PCV) and local tolerance at the injection site were measured during the study. FECs were comparable between the treatment and control groups at day 0. However, treatment of cattle with VERYL significantly (p < 0.001) reduced FECs by day 7 and sustained to day 21 post-treatment. Coproculture results for the treatment and control groups revealed presence of Haemonchus, Cooperia, Ostertagia, Trichostrongylus and Oesophagostomum species. Cattle treated with VERYL® had a significant (p < 0.05) reduction in larval recoveries compared to the control group. VERYL® had minimal adverse effects which cleared after a short while and is thus recommended for controlling GINs in cattle.


Assuntos
Anti-Helmínticos/uso terapêutico , Doenças dos Bovinos/tratamento farmacológico , Diminazena/análogos & derivados , Levamisol/uso terapêutico , Infecções por Nematoides/veterinária , Animais , Bovinos , Diminazena/uso terapêutico , Fezes/parasitologia , Haemonchus/isolamento & purificação , Quênia , Infecções por Nematoides/tratamento farmacológico , Contagem de Ovos de Parasitas/veterinária , Distribuição Aleatória , Trichostrongylus/isolamento & purificação
17.
Rev. bras. parasitol. vet ; 29(1): e015819, 2020. tab, graf
Artigo em Inglês | LILACS | ID: biblio-1092688

RESUMO

Abstract An evaluation was made of the effect of anthelmintic treatments on the performance of Simmental X Nellore crossbred calves before and after weaning. To this end, the calves were divided into three groups: (1) treated monthly with a low efficacy anthelmintic drug, ivermectin; (2) treated monthly with a highly effective anthelmintic drug, albendazole; and (3) untreated control group. All the groups in this experiment showed an average fecal egg count of less than 400 eggs per gram (EPG), and no clinical signs of parasitic gastroenteritis. The blood variables were within the normal range and no calf presented anemia. In most of the samplings, mean EPGs were significantly lower (P<0.05) in the group treated with albendazole. The calves received dietary supplementation before and after weaning, which enabled them to gain weight in every month of the experiment and reach a body weight of about 250 kg on the last sampling date, before turning one year old. The anthelmintic treatments did not affect body weight gain, leading to the conclusion that, when fed with suitable dietary supplements, Simmental X Nellore crossbred calves are not affected by gastrointestinal nematode parasites acquired by grazing.


Resumo O objetivo do experimento foi avaliar o efeito de tratamentos anti-helmínticos no desempenho de bezerros Simental x Nelore antes e após o desmame. Os bezerros foram alocados em três grupos: (1) tratado mensalmente com anti-helmínticos de baixa eficácia, ivermectina; (2) tratado mensalmente com anti-helmíntico de alta eficácia, albendazol e (3) controle não tratado. A média das contagens de ovos de nematoides durante o experimento foi inferior a 400 ovos por grama (OPG) em todos os grupos sem manifestação clínica de gastroenterite parasitária. As variáveis ​​sanguíneas mantiveram-se dentro dos limites de normalidade e nenhum bezerro apresentou anemia. Na maioria das coletas, as médias de OPG foram significativamente inferiores (P<0,05) no grupo tratado com albendazol. Os bezerros receberam suplementação antes e depois do desmame, o que lhes permitiu ganhar peso em todos os meses do experimento, atingindo peso corporal em torno de 250 kg, ao final do experimento, antes de completarem um ano de idade. Não houve efeito dos tratamentos anti-helmínticos no ganho em peso, o que permitiu concluir que bezerros Nelore x Simental não são afetados pelo parasitismo por nematoides gastrintestinais sob condições de pastejo, quando devidamente suplementados com concentrado.


Assuntos
Animais , Masculino , Feminino , Bovinos , Ivermectina/administração & dosagem , Albendazol/administração & dosagem , Doenças dos Bovinos/tratamento farmacológico , Gastroenteropatias/veterinária , Anti-Helmínticos/administração & dosagem , Infecções por Nematoides/veterinária , Contagem de Ovos de Parasitas/veterinária , Fezes/parasitologia , Gastroenteropatias/parasitologia , Gastroenteropatias/tratamento farmacológico , Infecções por Nematoides/parasitologia , Infecções por Nematoides/tratamento farmacológico
18.
Rev. bras. parasitol. vet ; 29(1): e013119, 2020. tab, graf
Artigo em Inglês | LILACS | ID: biblio-1058018

RESUMO

Abstract The objective of this study was to evaluate the efficacy of carvacryl acetate (CVA) and nanoencapsulated CVA (nCVA) on gastrointestinal nematodes of sheep. The CVA was nanoencapsulated with chitosan/gum arabic and the efficacy of nanoencapsulation (EE), yield, zeta potential, nanoparticle morphology and release kinetics at pH 3 and 8 were analyzed. Acute and subchronic toxicity were evaluated in rodents and reduction of egg counts in the faeces (FECRT) of sheep. The sheep were divided into four groups (n = 10): G1, 250 mg/kg CVA; G2, 250 mg/kg nCVA; G3, polymer matrix and G4: 2.5 mg/kg monepantel. EE and nCVA yield were 65% and 57%, respectively. The morphology of the nanoparticles was spherical, size (810.6±286.7 nm), zeta potential in pH 3.2 (+18.3 mV) and the 50% release of CVA at pHs 3 and 8 occurred at 200 and 10 h, respectively. nCVA showed LD50 of 2,609 mg/kg. CVA, nCVA and monepantel reduced the number of eggs per gram of faeces (epg) by 57.7%, 51.1% and 97.7%, respectively. The epg of sheep treated with CVA and nCVA did not differ from the negative control (P>0.05). Nanoencapsulation reduced the toxicity of CVA; however, nCVA and CVA presented similar results in the FECRT.


Resumo O objetivo deste trabalho foi avaliar a eficácia do acetato de carvacrila (ACV) e do ACV nanoencapsulado (nACV) sobre nematóides gastrintestinais de ovinos. O ACV foi nanoencapsulado com quitosana/goma arábica e foi analisada a eficácia de nanoencapsulamento (EE), o rendimento, potencial zeta, morfologia das nanopartículas e cinética de liberação em pH 3 e 8. Foram avaliadas as toxicidades aguda e subcrônica em roedores e a redução da contagem de ovos nas fezes (RCOF) de ovinos. Os ovinos foram divididos em quatro grupos (n = 10): G1, 250 mg/kg ACV; G2, 250 mg/kg de nACV; G3, matriz polimérica e G4: 2,5 mg/kg de monepantel. A EE e o rendimento de nACV foram de 65% e 57%, respectivamente. A morfologia das nanopartículas foi esférica, tamanho (810,6±286,7 nm), potencial zeta no pH 3,2 (+18,3 mV) e a liberação de 50% de CVA nos pHs 3 e 8 ocorreu às 200 e 10 h, respectivamente. nACV apresentou DL50 de 2.609 mg/kg. ACV, nACV e o monepantel reduziram a contagem de ovos por grama de fezes (opg) em 57,7%, 51,1% e 97,7%, respectivamente. A contagem de opg de ovelhas tratadas com ACV e nCVA não diferiu do controle negativo (P>0,05). O nanoencapsulamento reduziu a toxicidade do AVC; no entanto, nACV e ACV apresentaram resultados semelhantes na RCOF.


Assuntos
Animais , Feminino , Doenças dos Ovinos/tratamento farmacológico , Monoterpenos/administração & dosagem , Trato Gastrointestinal/parasitologia , Nanocápsulas/administração & dosagem , Anti-Helmínticos/administração & dosagem , Nematoides/efeitos dos fármacos , Infecções por Nematoides/tratamento farmacológico , Contagem de Ovos de Parasitas , Roedores , Doenças dos Ovinos/parasitologia , Ovinos , Testes de Toxicidade , Testes de Sensibilidade Parasitária , Monoterpenos/toxicidade , Nanocápsulas/toxicidade , Fezes/parasitologia , Reação em Cadeia da Polimerase em Tempo Real , Anti-Helmínticos/toxicidade , Camundongos , Nematoides/isolamento & purificação , Nematoides/classificação , Infecções por Nematoides/parasitologia
19.
Vet Parasitol Reg Stud Reports ; 18: 100325, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31796185

RESUMO

Gastrointestinal nematodes (GINs) have been identified in Australia as a major problem in goat production, with few anthelmintics registered for use in goats. Therefore, anecdotally many producers use anthelmintics that have not been registered for goats. Using unregistered products could increase selection pressure for anthelmintic resistance as well as safety and/or meat or milk chemical residues of products from treated goats. This producer survey was conducted in 2014 to establish Australian goat producer knowledge, perception and practises of GIN treatment and control. Eighty-eight producers responded to the survey. Of these respondents, 90% thought that GINs were a problem for the Australian goat industry, and 73% considered GINs had caused production losses or health impacts for their goats during the 5 years prior to the survey. With regard to anthelmintic resistance, 7% believed that anthelmintic resistance was not a problem at all, 93% acknowledged anthelmintic resistance was a problem in Australian goats herds, with 25% of these reporting their properties as being affected. The majority (81%) of respondents believed the number of anthelmintics registered for goats was inadequate for effective GIN control. Of the 85% of producers who used an anthelmintic during the survey period, 69% had used a treatment not registered for use in goats. Fifty respondents listed the anthelmintic dosage used, and 50% of those had used a dose rate greater than the recommended label dose. The average frequency of administration of anthelmintic was 2.5 times per annum. Of the 51% of respondents who listed the frequency of their treatments given during the survey period, 16% administered four or more treatments annually to the majority of their goats and 8% administered treatments on an "as needed" basis. Faecal egg count (FEC) had been performed on 72% of properties in at least one of the six years covered by the survey. These results indicated that the majority of surveyed producers use anthelmintics that are not registered for use in goats and at different dose rates to label. These practises have the potential for increasing the spread of anthelmintic resistance in the GIN populations of goats and sheep. Further, giving dose rates in excess of label recommendations could impact goat safety and/or product residues. Further research is needed to investigate these risks and evaluate more sustainable GIN control options for goat herds. In addition more effective dissemination of information is necessary for the improvement of the Australian goat industry.


Assuntos
Criação de Animais Domésticos , Anti-Helmínticos/uso terapêutico , Doenças das Cabras/tratamento farmacológico , Conhecimentos, Atitudes e Prática em Saúde , Infecções por Nematoides/veterinária , Uso Off-Label/veterinária , Criação de Animais Domésticos/métodos , Animais , Austrália , Resistência a Medicamentos , Trato Gastrointestinal/parasitologia , Cabras , Nematoides/efeitos dos fármacos , Infecções por Nematoides/tratamento farmacológico , Uso Off-Label/estatística & dados numéricos
20.
Pol J Vet Sci ; 22(4): 753-760, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31867918

RESUMO

We described a first case of resistance to eprinomectin in goat herd in Poland in which resistance to benzimidazoles had been previously reported. The herd was established in 2011 by purchasing several goats from a single herd in south-eastern Poland. Resistance to benzimidazoles in the herd was first reported in 2017. Shortly after the owner started to signal low effectiveness of the treatment with eprinomectin. In June 2018 the larval development test from pooled faecal sample was performed and the results indicated the presence of resistance to macrocyclic lactones and levamisole. In July 2018 a faecal egg count (FEC) reduction test was performed in 39 animals with levamisole, eprinomectin and one untreated control group. Drugs were used in doses recommended for goats. Three methods of calculation of FEC reduction were compared. After eprinomectin treatment, FEC reduction ranged from 0 to 20%, depending on the method of calculation. FEC reduction following levamisole treatment was 100%. Main species present in the faecal samples after treatment and in larvicidal concentrations in larval development test was Haemonchus contortus. This is the first report of anthelminthic resistance to macrocylic lactones (eprinomectin) in goats in Poland.


Assuntos
Benzimidazóis/farmacologia , Doenças das Cabras/tratamento farmacológico , Enteropatias Parasitárias/veterinária , Ivermectina/análogos & derivados , Nematoides/efeitos dos fármacos , Infecções por Nematoides/veterinária , Animais , Anti-Helmínticos/uso terapêutico , Resistência a Medicamentos , Fezes/parasitologia , Doenças das Cabras/parasitologia , Cabras , Enteropatias Parasitárias/tratamento farmacológico , Enteropatias Parasitárias/parasitologia , Ivermectina/uso terapêutico , Infecções por Nematoides/tratamento farmacológico , Infecções por Nematoides/parasitologia , Contagem de Ovos de Parasitas
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