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1.
Trop Anim Health Prod ; 55(2): 72, 2023 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-36757509

RESUMO

Improved management of livestock in resource-limited settings can provide a means towards improved human nutrition and livelihoods. However, gastrointestinal nematodes (GIN) are a significant production-limiting factor. Anthelmintics play a role in GIN management; however, few anthelmintic classes are available in many low-middle-income countries. Utilising a limited range of classes may increase selection for anthelmintic resistance; therefore, strategies to reduce other selective pressures are of heightened importance. Avoiding anthelmintic underdosing is one such strategy, but it can be challenging without access to accurate bodyweight measurement. Many previous studies have used thoracic girth as a practical proxy for bodyweight in goats; however, they have rarely considered the potential impact of natural variation on therapeutic doses. Here, the relationship between bodyweight and thoracic girth was modelled using data from 820 goats from three Malawian biomes in two seasons, with the specific aim of avoiding underestimation of bodyweight. The internally cross-validated linear regression (∛Weight ~ 0.053 + 0.040*Girth, R2 = 0.92, rounded up to the nearest 5 kg) was validated against data from an additional 352 Malawian goats (1.4% of goats allocated an underdose and 10.2% allocated a dose > 200% of bodyweight). The equation was further externally validated using an historical dataset of 150 goats from Assam, India (2.7% of goats were allocated to an underdose and 24.8% allocated to a > 200% of bodyweight). These results suggest that a more globally generalisable approach may be feasible, provided the accuracy of the estimate is considered alongside the therapeutic index of the pharmaceutical.


Assuntos
Anti-Helmínticos , Doenças das Cabras , Nematoides , Infecções por Nematoides , Animais , Humanos , Infecções por Nematoides/veterinária , Cabras , Doenças das Cabras/tratamento farmacológico , Resistência a Medicamentos , Contagem de Ovos de Parasitas/veterinária , Anti-Helmínticos/farmacologia
2.
N Z Vet J ; 68(3): 136-144, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31968203

RESUMO

Small ruminants are particularly well suited to meet United Nations Sustainable Development Goals surrounding food security, human wellbeing and poverty alleviation in different environmental and climatic settings. However the current efficiency of food production from small ruminants in both developed agricultural regions and in lower and middle income countries is woefully inadequate to meet predicted global needs over the forthcoming decades. Most global research to address this challenge is focussed on the genetics of animal growth, conformation and disease tolerance or resistance traits, albeit the practical consequences of such selection and strategies to use genetically improved animals in the field are uncertain. Any long-term benefits derived from small ruminant genetic selection will only be impactful if steps are first taken to keep animals alive, healthy and productive through iterative planned health management. Parasites are the foremost global infectious disease constraints to efficient small ruminant production. Their genetic adaptability to exploit opportunities afforded by effects of climatic or management changes on free-living stages, or exposure of parasitic stages to drugs, presents specific challenges to their sustainable control. Hence, parasite control provides a relevant means of engagement with livestock keepers and farmers on the topic of planned animal health management. The value of parasitology in this regard is enhanced by the availability of simple to use and accessible diagnostic tools.


Assuntos
Abastecimento de Alimentos , Doenças Parasitárias em Animais , Ruminantes/parasitologia , Criação de Animais Domésticos , Animais , Humanos , Gado , Doenças Parasitárias/prevenção & controle , Pobreza , Nações Unidas
4.
Parasite Immunol ; 36(11): 616-26, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25065384

RESUMO

Ectoparasites present a major challenge for disease management globally. With drug resistance increasingly observed in many disease-causing species, the need for novel control measures is pressing. Ever-expanding genomic resources from 'next generation' sequencing are now available for a number of arthropod ectoparasites, necessitating an effective means of screening these data for novel candidates for vaccine antigens or targets for chemotherapeutics. Such in vitro screening methods must be developed if we are to make discoveries in a timely and cost-effective manner. This review will discuss the potential that RNA interference (RNAi) has demonstrated thus far in the context of arthropod ectoparasites and the potential roles for this technology in the development of novel methods for parasite control.


Assuntos
Sistemas de Liberação de Medicamentos , Ectoparasitoses/tratamento farmacológico , Ectoparasitoses/veterinária , Interferência de RNA , Animais , Antígenos/imunologia , Ectoparasitoses/genética , Ectoparasitoses/imunologia , Humanos , Vacinas/economia , Vacinas/imunologia
5.
Artigo em Inglês | MEDLINE | ID: mdl-34896787

RESUMO

Haemonchus contortus is arguably one of the most economically important and ubiquitous parasites of livestock globally and commonly involved in cases of anthelmintic resistance. Here, we performed reciprocal genetic crosses using susceptible (MHco3(ISE)) and multiple anthelmintic resistant (MHco18(UGA2004)) H. contortus isolates. Resultant admixed populations were designated MHco3/18 or MHco18/3, where the lead isolate reflects the origin of the females. Three independent filial generations were generated for each cross, which were subjected to bioassays, molecular approaches and population genetic analyses to investigate the phenotypic and genotypic inheritance of benzimidazole (BZ) resistance at each stage. A panel of microsatellite markers confirmed the success of the genetic cross as markers from both parents were seen in the F1 crosses. Egg hatch tests revealed a stark difference between the two F1 crosses with ED50 estimates for MHco18/3 being 9 times greater than those for MHco3/18. Resistance factors based on ED50 estimates ranged from 6 to 57 fold in the filial progeny compared to MHco3(ISE) parents. Molecular analysis of the F167Y and F200Y SNP markers associated with BZ resistance were analysed by pyrosequencing and MiSeq deep amplicon sequencing, which showed that MHco3/18.F1 and MHco18/3.F1 both had similar frequencies of the F200Y resistant allele (45.3% and 44.3%, respectively), whereas for F167Y, MHco18/3.F1 had a two-fold greater frequency of the resistant-allele compared to MHco3/18.F1 (18.2% and 8.8%, respectively). Comparison between pyrosequencing and MiSeq amplicon sequencing revealed that the allele frequencies derived from both methods were concordant at codon 200 (rc = 0.97), but were less comparable for codon 167 (rc = 0.55). The use of controlled reciprocal genetic crosses have revealed a potential difference in BZ resistance phenotype dependent on whether the resistant allele is paternally or maternally inherited. These findings provide new insight and prompt further investigation into the inheritance of BZ resistance in H. contortus.


Assuntos
Anti-Helmínticos , Hemoncose , Haemonchus , Animais , Anti-Helmínticos/farmacologia , Benzimidazóis/farmacologia , Cruzamentos Genéticos , Resistência a Medicamentos/genética , Feminino , Hemoncose/tratamento farmacológico , Hemoncose/epidemiologia , Hemoncose/veterinária , Fenótipo , Polimorfismo de Nucleotídeo Único , Tubulina (Proteína)/genética
6.
Int J Parasitol ; 51(5): 393-403, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33460620

RESUMO

Anthelmintic resistance threatens the sustainability of sheep production globally. Advice regarding strategies to reduce the development of anthelmintic resistance incorporates the outcomes of modelling exercises. Further understanding of gastrointestinal nematode species diversity, and population dynamics and genetics (which may vary between species) is required to refine these models; and field studies combining faecal egg outputs, species composition and resistance genetics are needed to calibrate them. In this study, faecal samples were taken from ewes and lambs on a commercial farm in south-eastern Scotland at approximately 3 t-4 week intervals between spring and autumn over a period of 4 years. Faecal egg counts were performed on these samples, and L3 were collected from pooled coprocultures. Deep amplicon sequencing was used to determine both the species composition of these L3 and the proportions of benzimidazole-resistant single nucleotide polymorphisms in the isotype-1 ß-tubulin locus of the predominant species, Teladorsagia circumcincta L3. Despite consistent management throughout the study, the results show variation in gastrointestinal nematode species composition with time and between age groups, that was potentially associated with weather conditions. The F200Y benzimidazole resistance mutation is close to genetic fixation in the T. circumcincta population on this farm. There was no evidence of variation in isotype-1 ß-tubulin single nucleotide polymorphisms frequency between age groups, and no genetic evidence of reversion to benzimidazole susceptibility, despite targeted benzimidazole usage. This study highlights the need to include speciation when investigating gastrointestinal nematode epidemiology and anthelmintic resistance, and serves as an example of how genetic data may be analysed alongside species diversity and faecal egg counts, when markers for other anthelmintic classes are identified.


Assuntos
Anti-Helmínticos , Nematoides , Doenças dos Ovinos , Animais , Anti-Helmínticos/farmacologia , Anti-Helmínticos/uso terapêutico , Benzimidazóis/farmacologia , Resistência a Medicamentos , Fazendas , Fezes , Feminino , Genótipo , Nematoides/genética , Contagem de Ovos de Parasitas/veterinária , Escócia , Ovinos , Doenças dos Ovinos/tratamento farmacológico
7.
Prev Vet Med ; 186: 105225, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33348303

RESUMO

The world's growing population is becoming increasingly centred around large cities, affording opportunities for peri-urban food production. Goats are well-suited to conversion of resources that are available in peri-urban settings into meat and occasionally milk. Haemonchus contortus has been described as "the nemesis of small ruminant production systems in tropical and subtropical regions"; hence control of haemonchosis through planned animal health management affords a pragmatic first step in improving the production efficiency of peri-urban goats. This study of peri-urban goat production investigated the potential value of targeted selective treatment of haemonchosis. 452 peri-urban goat keepers in southern Malawi were visited during three seasonal periods with relevance to the epidemiology of haemonchosis. 622, 599 and 455 individually identified goats were clinically examined during the dry season, the rainy season, and shortly after the end of the rainy season, respectively. Data were recorded for sex, age, weight, conjunctival mucous membrane colour score (FAMACHA©), body condition score (BCS) and faecal worm egg count (FEC); and where possible for pregnancy and lactation status. Animals with pale ocular mucous membranes were treated with 10 mg/kg albendazole, then re-examined 14 days later. Animals with pink mucous membranes, but FECs ≥250 eggs per gram were also re-examined and treated 14 days later. The results show high variability in growth rates deduced from the ages and bodyweights of each of 999 goats at the time of their enrolment. FAMACHA© scores alone were a poor index for the targeted selective treatment of haemonchosis, because they failed to identify too many animals that would have required treatment at different times of year and using different FAMACHA© and FEC cut-offs. Combining the indices of FAMACHA© scores ≥4, body condition scores ≥2, and age >18 months was more reliable in identifying those animals requiring treatment when different epidemiologically-relevant FEC thresholds for different seasons were taken into account. Inclusion of late pregnancy or early lactation status would have resulted in very few animals requiring treatment being missed. The use of conjunctival mucous membrane colour scoring in this way provided a valuable insight of the general health status of the peri-urban goats, to create opportunities for planned animal health management to improve productivity. The efficacy of albendazole treatment was poor, putatively due to drug resistance, or poor drug bioavailability in goats. In summary, our study shows opportunities for better production efficiency in peri-urban goats, and demonstrates the value of simple clinical diagnostic indices as decision support tools in planned animal health management.


Assuntos
Anti-Helmínticos/administração & dosagem , Túnica Conjuntiva/fisiologia , Resistência a Medicamentos , Doenças das Cabras/tratamento farmacológico , Cabras/fisiologia , Hemoncose/veterinária , Animais , Cor , Feminino , Doenças das Cabras/parasitologia , Hemoncose/tratamento farmacológico , Hemoncose/parasitologia , Haemonchus/fisiologia , Malaui , Masculino , Mucosa/fisiologia
8.
Parasitol Int ; 78: 102146, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32442496

RESUMO

A recurrent mite infestation affecting a room used to inspect fabric in a UK textile mill was investigated to allay concerns of any potential health risks to factory staff, and to inform the unknown risk of downgrading of the product. The approach integrated conventional morphological examination of adult female mites by referring to published identification keys, with molecular speciation based on amplification of a 16S ribosomal DNA fragment. The methods enabled the mites to be unambiguously identified as Dermanyssus gallinae 'special lineage L1'. Subsequent investigations showed the source of infestation to be pigeons nesting in the air ducts, with the gamasid mites moving into the room once the young birds had fledged. This is the first report of D. gallinae 'special lineage L1' in northern Europe. Previous reports of nosocominal gamasoidosis caused by D. gallinae 'special lineage L1' originating from feral pigeon populations have been from southern Europe. Confirmation of the mite identity was important in allowing the mill to take remedial and preventive action. In this clinical communication, we provide images of the key morphological features used to identify D. gallinae and describe a molecular protocol to confirm 'special lineage L1'.


Assuntos
Infestações por Ácaros/parasitologia , Ácaros/classificação , Indústria Têxtil , Animais , Feminino , Ácaros/fisiologia , RNA Ribossômico 16S/análise , Reino Unido
9.
Vet Rec ; 162(17): 546-50, 2008 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-18441350

RESUMO

The epidemiology of nematode infections in a UK commercial crossbred sheep flock was studied from January 2004 to January 2005. The ewes were treated orally with moxidectin when they were turned out of the lambing shed on to nematode-contaminated pasture, and the lambs were treated orally with ivermectin throughout the summer in accordance with the farm's usual practice, with the aim of near-suppressive nematode control. The lactating ewes experienced a significant increase in faecal egg count during the early summer, after the period of persistence of the moxidectin treatment had ended. The ewes' and lambs' egg outputs were dominated by Teladorsagia species, despite the persistence of the effect of moxidectin against this genus. The gimmers (primiparous two-year-old ewes) had a significantly greater faecal egg count at lambing than the three- to four-year-old ewes, but the older ewes had significantly greater post-treatment increases. The population of Trichostrongylus species appeared to follow accepted epidemiological patterns, with no evidence of summer trichostrongylosis. In late summer and autumn the faecal egg output of the ewes was primarily due to large intestinal nematodes.


Assuntos
Gastroenterite/veterinária , Infecções por Nematoides/veterinária , Doenças dos Ovinos/epidemiologia , Criação de Animais Domésticos , Animais , Antinematódeos/administração & dosagem , Fezes/parasitologia , Feminino , Gastroenterite/tratamento farmacológico , Gastroenterite/epidemiologia , Gastroenterite/parasitologia , Ivermectina/administração & dosagem , Macrolídeos/administração & dosagem , Masculino , Infecções por Nematoides/tratamento farmacológico , Infecções por Nematoides/epidemiologia , Contagem de Ovos de Parasitas/veterinária , Ovinos , Doenças dos Ovinos/tratamento farmacológico , Doenças dos Ovinos/parasitologia , Trichostrongylus/isolamento & purificação , Reino Unido/epidemiologia
10.
Vet Parasitol ; 147(3-4): 326-31, 2007 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-17531390

RESUMO

The cause of ill thrift and deaths was investigated in a group of 40 Scottish lowground ewes, which had been treated with levamisole and then turned onto clean grazing after lambing, 6-8 weeks previously. Concurrent haemonchosis and teladorsagiosis were diagnosed, putatively associated with the spring maturation of large numbers of hypobiotic larvae. Ill thrift due to parasitic gastroenteritis consequently occurred in the lambs which had been turned onto the 'clean' grazing with their dams, despite metaphylactic anthelmintic treatments. The contributory role of haemonchosis resulting in serious production-limiting disease is unusual in Scottish sheep flocks. It is suggested that the problem may have arisen as a consequence of the adaptation of Haemonchus contortus to survive overwinter in a cold climate as arrested early fourth stage larvae, which were not eliminated when the ewes were treated with levamisole at turnout.


Assuntos
Hemoncose/veterinária , Doenças dos Ovinos/parasitologia , Animais , Anti-Helmínticos/uso terapêutico , Feminino , Hemoncose/diagnóstico , Hemoncose/epidemiologia , Hemoncose/parasitologia , Ivermectina/uso terapêutico , Larva , Escócia/epidemiologia , Estações do Ano , Ovinos , Doenças dos Ovinos/diagnóstico , Doenças dos Ovinos/epidemiologia , Fatores de Tempo
11.
Vet Parasitol ; 145(1-2): 65-76, 2007 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-17134836

RESUMO

Multiple resistance to benzimidazole, imidazothiazole and macrocyclic lactone anthelmintics is an emerging problem in the south-east of Scotland. The general management and nematode control strategies employed in four affected flocks (flocks 1-4) were investigated in an attempt to identify the risk factors which might have led to the appearance of production limiting disease associated with anthelmintic resistance. The important risk factors for multiple anthelmintic resistance could not be confirmed and it proved easier to criticise nematode control practices on theoretical grounds, than to propose practical solutions. It seems likely that different risk factors were involved in the four flocks. Lambs in flocks 1 and 2 had been treated with an anthelmintic at 3-4 weekly intervals with the aim of achieving suppressive nematode control, while sheep in flock 1 had been treated with an anthelmintic after they were moved onto clean grazing. Recently lambed ewes had been treated with moxidectin in three of the four flocks, with the aim of controlling their periparturient rise in faecal nematode egg output. All of these factors might have contributed to the emergence of multiple anthelmintic resistance, because they could have led to anthelmintic treatments at times when the nematode population in refugia was small, compared to that in the sheep. Annual rotation of the anthelmintic group was compromised by the emergence of benzimidazole resistance and did not prevent the emergence of multiple resistance in any of the flocks described, although the practice may have slowed the development of resistance. Underdosing may have selected for benzimidazole and imidazothiazole resistance in flock 2, associated with inaccurate estimation of the weights of terminal sire lambs. These investigations also highlighted problems associated with the diagnosis of anthelmintic resistance, in particular the confounding effects of the onset of host immunity to nematode parasites, the possible influence of the age of the adult nematode population, and the insensitivity of the undifferentiated faecal egg count reduction test in situations where resistance is emerging.


Assuntos
Anti-Helmínticos/farmacologia , Resistência a Múltiplos Medicamentos , Helmintíase Animal/parasitologia , Doenças dos Ovinos/parasitologia , Animais , Feminino , Helmintíase Animal/tratamento farmacológico , Helmintíase Animal/epidemiologia , Masculino , Escócia/epidemiologia , Ovinos , Doenças dos Ovinos/tratamento farmacológico , Doenças dos Ovinos/epidemiologia
12.
Vet J ; 173(3): 522-31, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-16632388

RESUMO

Data from industry sources detailing variable costs in 2003 revealed that the average farmer keeping 1000 lowland ewes in the United Kingdom spent 3500 UK pounds annually on veterinary fees and medicines. Despite such expenditure, psoroptic mange and cutaneous myiasis are common in the UK, resistance to one or more anthelmintic group is not only common but increasing in frequency and distribution, and abortion outbreaks caused by Toxoplasma gondii and Chlamydophila abortus are frequently reported by veterinary laboratories. Welfare concerns also arise from farmers' intransigence towards tail docking and castration in lambs (mutilations), reported market forces necessitating long distance road transportation to slaughter plants, and an unwillingness to employ veterinary surgeons for obstetrical problems. The spread of sheep scab in the UK over the past decade illustrates the failure of flock owners to effect rudimentary biosecurity and disease control measures. A first step towards improving the health and welfare of sheep would be the immediate implementation of basic good husbandry practices, including ectoparasiticide treatment for sheep scab eradication, prophylaxis for cutaneous myiasis in selected lambs, and appropriate vaccination strategies for clostridial diseases and certain abortion agents. There would also be money from within current farm expenditure to provide veterinary attention for obstetrical problems affecting up to 2% of ewes per annum. Planned use of ecto- and endoparasiticides is urgently needed to maintain the efficacy of these unique drugs.


Assuntos
Bem-Estar do Animal , Doenças dos Ovinos/prevenção & controle , Vacinação/veterinária , Medicina Veterinária/economia , Medicina Veterinária/normas , Criação de Animais Domésticos/economia , Criação de Animais Domésticos/métodos , Animais , Análise Custo-Benefício , Feminino , Masculino , Infestações por Ácaros/economia , Infestações por Ácaros/epidemiologia , Infestações por Ácaros/prevenção & controle , Infestações por Ácaros/veterinária , Miíase/economia , Miíase/epidemiologia , Miíase/prevenção & controle , Miíase/veterinária , Ovinos , Doenças dos Ovinos/economia , Doenças dos Ovinos/epidemiologia , Reino Unido
13.
Vet Rec ; 180(11): 278, 2017 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-28302888

RESUMO

Here the authors report the objective veterinary clinical measurement of productivity in a representative south Indian Malabari goat herd. The authors show failure to meet pragmatic production targets that are commensurate with the animals' genetic potential or adequate to meet the demands of global food security. The authors suggest that this situation may have arisen as a consequence of animal husbandry constraints and protein undernutrition and imply the involvement of nematode parasitism. Benzimidazole resistance was detected in Haemonchus species, showing the need for better understanding of the principles of sustainable helminth parasite control within the southern Indian context. This study highlights the need to understand the true costs of goat production in seasonally resource-poor environments, while also considering its impact on the overall ecosystem in which the animals are placed. They conclude that pragmatic opportunities for improvements in goat production efficiency lie in the development of problem-focused planned animal health and nutrition management.


Assuntos
Criação de Animais Domésticos/organização & administração , Abastecimento de Alimentos , Cabras/fisiologia , Animais , Humanos , Índia
14.
Adv Parasitol ; 93: 95-143, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27238004

RESUMO

The parasitic nematode Haemonchus contortus occurs commonly in small ruminants, and it is an especially significant threat to the health and production of sheep and goats in tropical and warm temperate zones. The main signs of disease (haemonchosis) relate to its blood-feeding activity, leading to anaemia, weakness and frequently to deaths, unless treatment is provided. Due to the high biotic potential, large burdens of H. contortus may develop rapidly when environmental conditions favour the free-living stages, and deaths may occur with little prior warning. More chronic forms of haemonchosis, resulting in reduced animal production and eventually deaths, occur with smaller persistent infections, especially in situations of prolonged, poor nutrition. The global distribution of the main haemonchosis-endemic zones is consistent with the critical requirements of the egg and larval stages of H. contortus for moisture and moderate to relatively warm temperatures, but the seasonal propensity for hypobiosis (inhibition of the fourth-stage larvae within the host) largely explains the common, though sporadic, outbreaks of haemonchosis in arid and colder environments. The wide climatic distribution may also reflect the adaptation of local isolates to less favourable ecological conditions, while an apparent increase in the prevalence of outbreaks in environments not previously considered endemic for haemonchosis - especially cold, temperate zones - may be attributable to climatic changes. Although the risk of haemonchosis varies considerably on a local level, even where H. contortus is endemic, the extensive range of ecological investigations provides a sound basis for predictions of the relative geographical and seasonal risk in relation to climatic conditions.


Assuntos
Doenças das Cabras/epidemiologia , Hemoncose/veterinária , Haemonchus/fisiologia , Interações Hospedeiro-Parasita , Doenças dos Ovinos/epidemiologia , Animais , Clima , Ecologia , Doenças das Cabras/parasitologia , Cabras , Hemoncose/epidemiologia , Hemoncose/parasitologia , Prevalência , Ovinos , Doenças dos Ovinos/parasitologia , Temperatura
15.
Adv Parasitol ; 93: 181-238, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27238006

RESUMO

Haemonchus contortus is a highly pathogenic, blood-feeding nematode of small ruminants, and a significant cause of mortalities worldwide. Haemonchosis is a particularly significant threat in tropical, subtropical and warm temperate regions, where warm and moist conditions favour the free-living stages, but periodic outbreaks occur more widely during periods of transient environmental favourability. The clinical diagnosis of haemonchosis is based mostly on the detection of anaemia in association with a characteristic epidemiological picture, and confirmed at postmortem by the finding of large numbers of H. contortus in the abomasum. The detection of impending haemonchosis relies chiefly on periodic monitoring for anaemia, including through the 'FAMACHA' conjunctival-colour index, or through faecal worm egg counts and other laboratory procedures. A range of anthelmintics for use against H. contortus is available, but in most endemic situations anthelmintic resistance significantly limits the available treatment options. Effective preventative programmes vary depending on environments and enterprise types, and according to the scale of the haemonchosis risk and the local epidemiology of infections, but should aim to prevent disease outbreaks while maintaining anthelmintic efficacy. Appropriate strategies include animal management programmes to avoid excessive H. contortus challenge, genetic and nutritional approaches to enhance resistance and resilience to infection, and the monitoring of H. contortus infection on an individual animal or flock basis. Specific strategies to manage anthelmintic resistance centre on the appropriate use of effective anthelmintics, and refugia-based treatment schedules. Alternative approaches, such as biological control, may also prove useful, and vaccination against H. contortus appears to have significant potential in control programmes.


Assuntos
Anti-Helmínticos/uso terapêutico , Surtos de Doenças/veterinária , Doenças das Cabras/parasitologia , Hemoncose/veterinária , Haemonchus/efeitos dos fármacos , Doenças dos Ovinos/parasitologia , Animais , Surtos de Doenças/prevenção & controle , Resistência a Medicamentos , Fezes/parasitologia , Doenças das Cabras/diagnóstico , Doenças das Cabras/terapia , Cabras , Hemoncose/diagnóstico , Hemoncose/epidemiologia , Hemoncose/terapia , Haemonchus/isolamento & purificação , Contagem de Ovos de Parasitas/veterinária , Ovinos , Doenças dos Ovinos/diagnóstico , Doenças dos Ovinos/terapia
16.
Vet J ; 170(3): 325-31, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16198611

RESUMO

A naturally occurring outbreak of subacute fasciolosis in a group of 17 seven-month-old Soay ram lambs was studied following the sudden death of two sheep. In addition to standard biochemical investigations, ultrasound examination of the liver and cranial abdominal cavity was undertaken. There was a significant positive linear correlation between liver weight and ultrasonographic determination of liver size (R=0.72, P<0.05). Ultrasonographic examination of the liver revealed multiple hyperechoic dots in the parenchyma giving a granular appearance to the hepatic texture in three sheep corresponding to the most advanced histopathological changes as determined by the size of the abscesses and their relatively mature fibrous capsules, and areas of hepatic necrosis. No distension of the bile duct system was noted nor was the gall bladder imaged. While serum concentrations of albumin, globulin and certain liver enzymes assisted in the diagnosis of subacute fasciolosis in sheep, only glutamate dehydrogenase, and gammaglutamyl transferase remained elevated four weeks after triclabendazole treatment.


Assuntos
Surtos de Doenças/veterinária , Fasciolíase/veterinária , Fígado/patologia , Doenças dos Ovinos/epidemiologia , Animais , Fasciolíase/epidemiologia , Fasciolíase/patologia , Evolução Fatal , Feminino , Fígado/diagnóstico por imagem , Fígado/enzimologia , Masculino , Tamanho do Órgão , Ovinos , Doenças dos Ovinos/patologia , Ultrassonografia
17.
Vet Rec ; 156(4): 105-9, 2005 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-15704550

RESUMO

Control of a benzimidazole-, levamisole- and ivermectin-resistant population of Teladorsagia circumcincta was attempted using moxidectin administered orally at the manufacturer's recommended dose rate of 200 microg/kg bodyweight. Ewes were dosed after lambing with the aim of controlling their periparturient rise in faecal egg output and lambs were dosed at six-week intervals throughout the summer. This regimen failed to suppress the establishment of significant numbers of infective helminth larvae on the pasture, resulting in unsatisfactory lamb production. Oral dosing with moxidectin was effective in removing adult female burdens of ivermectin-resistant T. circumcincta, but the effect of the drug did not persist against the resistant helminth population.


Assuntos
Anti-Helmínticos/uso terapêutico , Macrolídeos/uso terapêutico , Doenças dos Ovinos/tratamento farmacológico , Trichostrongyloidea/efeitos dos fármacos , Tricostrongiloidíase/veterinária , Administração Oral , Animais , Animais Recém-Nascidos , Anti-Helmínticos/farmacologia , Benzimidazóis/farmacologia , Benzimidazóis/uso terapêutico , Fezes/parasitologia , Feminino , Gastroenteropatias/tratamento farmacológico , Gastroenteropatias/parasitologia , Gastroenteropatias/veterinária , Ivermectina/farmacologia , Ivermectina/uso terapêutico , Levamisol/farmacologia , Levamisol/uso terapêutico , Macrolídeos/farmacologia , Contagem de Ovos de Parasitas/veterinária , Ovinos , Trichostrongyloidea/crescimento & desenvolvimento , Tricostrongiloidíase/tratamento farmacológico , Tricostrongiloidíase/parasitologia
18.
N Z Vet J ; 63(5): 284-7, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25695509

RESUMO

CASE HISTORY: One hundred and forty Cheviot and 100 Suffolk cross Mule primiparous 1-2-year-old ewes, from a flock of about 700 ewes, were vaccinated with an attenuated live 1B strain Chlamydia abortus vaccine about 4 weeks before ram introduction (September 2011). Between 08 March and 01 April 2012, 50 2-year-old ewes aborted and 29 of these died, despite antimicrobial and anti-inflammatory treatment and supportive care. PATHOLOGICAL FINDINGS: Seven fetuses and three placentae from five 2-year-old ewes were submitted for pathological investigation. The aborted fetuses showed stages of autolysis ranging from being moderately fresh to putrefaction. Unusual, large multifocal regions of thickened membranes, with a dull red granular surface and moderate amounts of grey-white surface exudate were seen on each of the placentae. Intracellular, magenta-staining, acid fast inclusions were identified in Ziehl Neelsen-stained placental smears. Immunohistochemistry for Chlamydia-specific lipopolysaccharide showed extensive positive labelling of the placental epithelia. LABORATORY FINDINGS: Molecular analyses of the aborted placentae demonstrated the presence of the 1B vaccine-type strain of C. abortus and absence of any wild-type field strain. The vaccine strain bacterial load of the placental tissue samples was consistent with there being an association between vaccination and abortion. DIAGNOSIS: Initial laboratory investigations resulted in a diagnosis of chlamydial abortion. Further investigations led to the identification of the 1B vaccine strain of C. abortus in material from all three of the submitted aborted placentae. CLINICAL RELEVANCE: Timely knowledge and understanding of any potential problems caused by vaccination against C. abortus are prerequisites for sustainable control of chlamydial abortion. This report describes the investigation of an atypical abortion storm in sheep, and describes the identification of the 1B vaccine strain of C. abortus in products of abortion. The significance of this novel putative association between the vaccine strain of C. abortus and severe clinical disease is unknown. Aspects of the approach that is described are relevant to the investigation of all outbreaks of ovine abortion, irrespective of the diagnosis. Awareness of the changing role of C. abortus as a major global cause of abortion ought to reinforce the importance of monitoring of adequate biosecurity in those countries which are currently free from chlamydial abortion.


Assuntos
Aborto Animal/microbiologia , Vacinas Bacterianas/imunologia , Infecções por Chlamydia/veterinária , Chlamydia/classificação , Placenta/microbiologia , Toxemia/veterinária , Animais , Vacinas Bacterianas/microbiologia , Infecções por Chlamydia/prevenção & controle , Feminino , Gravidez , Ovinos , Doenças dos Ovinos/microbiologia , Toxemia/microbiologia
19.
Theriogenology ; 43(7): 1175-8, 1995 May.
Artigo em Inglês | MEDLINE | ID: mdl-16727703

RESUMO

Two millilitres of solution calculated to contain 0.07 mg/kg xylazine and 0.5 mg/kg lignocaine injected at the sacrococcygeal epidural site provided caudal analgesia within 2 min in 61 sheep. This analgesic protocol eliminated forceful abdominal straining behavior following replacement of vaginal prolapse for at least 24 h in 48 of 52 ewes (92%) and in all 9 ewes with uterine prolapse. Moderate pelvic limb ataxia was observed in 25 sheep (41%) for up to 24 h after epidural injection. Sedation was noted in one ewe but no other systemic effects of xylazine injection, such as excessive salivation or ruminal distension, were observed. No long-term adverse reactions to xylazine injection were noted. The combined epidural injection regimen of xylazine and lignocaine is recommended as an adjunct for pain relief and control of abdominal straining following replacement of vaginal and uterine prolapse in ewes.

20.
Theriogenology ; 42(5): 891-3, 1994 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16727594

RESUMO

A 2% lignocaine solution infused at a dose of 2 mg/kg at the lumbosacral site gave excellent analgesia in 28 vasectomy operations and in 33 of 38 (87%) Caesarian operations at a dose of 4 mg/kg. Failure of the anesthetic technique in 4 sheep (6% of all operations) was associated with poor positioning of the ewe and incorrect identification of the epidural space. One fatality was recorded and was considered to result from lignocaine overdosage and the probable pooling of blood in the splanchnic vasculature. Pelvic limb paresis persisted for 2 to 4 h post epidural injection in all ewes, but no permanent paralysis was encountered. Lumbosacral epidural anesthesia gave excellent analgesia for vasectomy, and was indicated for Caesarian surgery when a dystocia was associated with severe vaginal prolapse or the delivery of a fetal monster. Further work is needed to find an analgesic preparation which has a shorter duration than the 2% lignocaine solution.

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