Strongyle faecal egg counts in Swiss horses: A retrospective analysis after the introduction of a selective treatment strategy.

The standard parasite management of horses based on regular anthelmintic treatments, now practiced for decades has resulted in a worrying expansion of resistant helminth populations, which may considerably impair control on the farm level. The aim of the present study was to obtain a retrospective (year 2010 - 2016) nationwide analysis of faecal egg count (FEC) data from the Swiss adult horse population, related to horse age and geographic region. Thirteen labs provided a total of 16,387 FEC data of horses aged four to 39 years (average: 13.6 years). The annual number of performed FEC tests increased from 38 to 4,939 within the observation period. Independent of the annual sample size the yearly patterns of the FEC were very similar. Seventy-eight percent (n = 12,840) of the samples were negative and 90 % (n = 14,720) showed a FEC below 200 strongyle eggs per gram (EPG) of faeces. The annual mean strongyle FEC ranged between 60 and 88 EPG with a total mean of 75 EPG. Horses aged 4-7 years showed a significantly (p < 0.00001) higher mean FEC compared with the other age groups, differences were not significant among the older horses. Based on ZIP codes, samples were allocated by 70.0 %, 6.0 % and 0.2 % to the German-, French- and Italian-speaking regions of Switzerland, respectively. With 222 EPG the mean FEC in the French part of Switzerland was significantly higher (p < 0.05) than in the German-speaking region (60 EPG). Eggs of Parascaris spp., anoplocephalids and Strongyloides westeri were found in 0.36 %, 0.32 % and 0.01 % of the samples, respectively. Based on 3,813 questionnaire feedbacks from owners in 2017 covering a total of 12,689 horses, sixty-eight percent (n = 8,476) were dewormed without diagnosis, two percent (n = 240) were not dewormed at all, whereas for 30 % (n = 3,721) the selective anthelmintic treatment (SAT) concept was applied. The SAT implementation rate differed significantly (p < 0.0005) between regions, with 33 %, 20 % and 25 % for the German-, French- and Italian-speaking areas, respectively. The rate of horses spending 16-24 h on pasture per day was significantly higher in the French-speaking region compared to the German-speaking part of Switzerland (p < 0.0001). In addition, pasture hygiene was practiced at a significantly lower rate in the French-speaking part compared to the German- and Italian-speaking regions (both p < 0.0001). Overall, the shift towards the SAT-concept represents a very promising development with respect to mitigating the further spread of anthelmintic resistance.

[Control of gastrointestinal helminths in goats in a mixed grazing system with cattle]. / Helminthenkontrolle bei Ziegen durch die gemeinsame Weidenutzung mit ­Rindern.

INTRODUCTION: Due to the widespread resistance of small ruminant gastrointestinal nematodes (GIN) against anthelmintic drugs the established control strategies need to get adapted, aiming to reduce their high dependence from chemical drugs. Host-specific development of GIN can be used as a tool when grazing different species on the same pastures. The aim of this study was to estimate the effect of mixed grazing with cattle on the development of GIN infections in goats. Goat flocks with 3 heifers (Group Mix; Visp: n = 12, Chur: n = 15) and without heifers (Group Solo; Visp: n = 7, Chur: n = 15) were grazed separately on pastures at altitudes of 910 m (location Chur) and 1240 m (location Visp) above sea level resp. during one grazing season each. The composition of the mixed groups aimed to achieve a similar intake of roughage of both species. The stocking rate and the availability of roughage in the solo groups was balanced proportionately according to the situation in the mixed groups. The individual GIN egg excretion, the composition of the GIN larvae in the faeces, the FAMACHA©-Score and the pasture contamination with infective GIN larvae was determined in monthly intervals. At both sites the goats in the mixed groups showed a significantly lower mean GIN egg excretion compared with those of the Solo groups (p .

INTRODUCTION: En raison de la résistance généralisée des nématodes gastro-intestinaux (NGI) des petits ruminants aux médicaments anthelminthiques, les stratégies de contrôle établies doivent être adaptées, visant à réduire leur forte dépendance aux substances chimiques. Le développement des NGI spécifiques à leur hôte peut être exploité, en introduisant la présence de différentes espèces d'hôtes sur les mêmes pâturages. Le but de cette étude était d'estimer l'effet du pâturage mixte avec des bovins sur le développement d'infections à NGI chez les chèvres. Des troupeaux de chèvres avec 3 génisses (Groupe Mix : Viège : n = 12, Coire : n = 15) et sans génisses (Groupe Solo : Viège : n = 7, Coire : n = 15) ont été placés sur des pâturages à des altitudes de 910 m (Coire) et 1240 m (Viège) au-dessus du niveau de la mer pendant une saison de pâturage. La composition des groupes mixtes visait à obtenir une consommation similaire de fourrage des deux espèces. La densité animale et la disponibilité du fourrage dans les groupes solos étaient en proportion comparables aux groupes mixtes. L'excrétion individuelle d'oeufs de NGI, les variétés de genres de NGI dans les fèces, le taux d'anémie (score FAMACHA©) et la contamination des pâturages par des larves infectieuses de NGI ont été déterminés à intervalles mensuels. Sur les deux sites, les chèvres des groupes Mix ont montré une excrétion d'oeufs de NGI significativement inférieure par rapport à celle des groupes Solo (p .

Implications of between-isolate variation for climate change impact modelling of Haemonchus contortus populations.

The impact of climate change on parasites and parasitic diseases is a growing concern and numerous empirical and mechanistic models have been developed to predict climate-driven spatial and temporal changes in the distribution of parasites and disease risk. Variation in parasite phenotype and life-history traits between isolates could undermine the application of such models at broad spatial scales. Seasonal variation in the transmission of the haematophagous gastrointestinal nematode Haemonchus contortus, one of the most pathogenic helminth species infecting sheep and goats worldwide, is primarily determined by the impact of environmental conditions on the free-living stages. To evaluate variability in the development success and mortality of the free-living stages of H. contortus and the impact of this variability on future climate impact modelling, three isolates of diverse origin were cultured at a range of temperatures between 15°C and 37°C to determine their development success compared with simulations using the GLOWORM-FL H. contortus model. No significant difference was observed in the developmental success of the three isolates of H. contortus tested, nor between isolates and model simulations. However, development success of all isolates at 37°C was lower than predicted by the model, suggesting the potential for overestimation of transmission risk at higher temperatures, such as those predicted under some scenarios of climate change. Recommendations are made for future climate impact modelling of gastrointestinal nematodes.

[,Targeted' and 'targeted selective treatments' in goats: Evaluation of several decision criteria and development of a practical decision key]. / Gezielte anthelminthische Behandlung bei Ziegen: Evaluation verschiedener Bewertungskriterien und Entwicklung eines praxisnahen Entscheidungsschlüssels.

INTRODUCTION: The aim of the study was to get an overview of control measures against gastrointestinal nematodes in goats in Switzerland. Based on the answers to a questionnaire, we assessed the readiness of owners to use targeted or targeted selective treatment, and to develop a practical decision tool for the indication of treatment of individual animals. The results show that the number of treatments per year decreased compared to previous studies. Furthermore, the survey shows that a large proportion of goat farmers (73.9%) is willing to change the present treatment strategy. A simple decision key based on the evaluation of body condition, the consistency of the faeces and the degree of the anaemia (FAMACHA©) was tested in a field survey. It could be shown that goat owners are able to carry out the simple protocol reliably on their own and correctly evaluate individuals regarding their need of treatment.

INTRODUCTION: Le but du présent travail était, sur la base d'une enquête, d'obtenir une vision d'ensemble du contrôle des nématodes gastro-intestinaux chez les chèvres en Suisse, d'estimer la disposition des éleveurs pour effectuer des traitements ciblés et de développer une méthode permettant de mesurer la nécessité d'un traitement individuel des animaux. Les résultats montrent que, par rapport à d'anciennes études, le nombre annuel de traitements anthelminthiques pourrait être réduit. Un grand nombre de propriétaires de chèvres (73.9%) sont prêts à modifier leur régime actuel de vermifugation. Une clé de décision, comprenant une estimation de l'état d'embonpoint, de la consistance des selles ainsi que du degré d'anémie (FAMACHA©) a été testée en pratique. Les détenteurs étaient à même, après une formation, de remplir seuls et de façon fiable le protocole et d'estimer ainsi correctement le besoin de traitement de leurs animaux.

Practices to optimise gastrointestinal nematode control on sheep, goat and cattle farms in Europe using targeted (selective) treatments.

Due to the development of anthelmintic resistance, there have been calls for more sustainable nematode control practices. Two important concepts were introduced to study and promote the sustainable use of anthelmintics: targeted treatments (TT), where the whole flock/herd is treated based on knowledge of the risk, or parameters that quantify the severity of infection; and targeted selective treatments (TST), where only individual animals within the grazing group are treated. The aim of the TT and TST approaches is to effectively control nematode-induced production impacts while preserving anthelmintic efficacy by maintaining a pool of untreated parasites in refugia. Here, we provide an overview of recent studies that assess the use of TT/TST against gastrointestinal nematodes in ruminants and investigate the economic consequences, feasibility and knowledge gaps associated with TST. We conclude that TT/TST approaches are ready to be used and provide practical benefits today. However, a major shift in mentality will be required to make these approaches common practice in parasite control.

[Helminth control in the adult horse: the need for a re-orientation]. / Helminthenmanagement beim adulten Pferd: Notwendigkeit einer Neuorientierung.

The epidemiological situation of strongyle infections in adult horses in Switzerland is characterized by a strong dominance of small strongyles (Cyathostominae) and an overall low level of egg shedding in the faeces. The prevailing attitude towards anthelmintic therapy considers neither husbandry conditions nor pasture hygiene measures. Instead, calendar-based routine medication, comprising usually 3 to 4 annual treatments, is the typical strategy. Such an approach, however, often results in an excessive administration of anthelmintics. With respect to the continuous spread of drug resistant cyathostomins a change of strategy seems inevitable. A consensus has been agreed on between equine parasitologists and clinicians of the Vetsuisse Faculty in Zurich and Berne to focus on the concept of a selective control approach, based on individual faecal egg counts as the central element. It is now recommended that clinically healthy horses (> 4 y) are treated only when their strongyle egg count is equal to or higher than 200 eggs per gram of faeces. A regular analysis of the strongyle population based on larval cultures, the control of drug efficacy, and quarantine measures for incoming horses are mandatory components of the concept. Recent experiences in several pilot farms have indicated that only 4 % of the McMaster analyses resulted in a deworming treatment. For horses that did not receive any nematicidal anthelmintic during the current season, a "safety" treatment is recommended at the end of the grazing period.

En Suisse, la situation épidémiologique des infestations des chevaux adultes par les strongylidés est caractérisée par une nette dominance des petits strongles (Cyathostominae) et par un faible niveau d'excrétion des œufs de parasites dans les selles. Cars les conditions de détention des chevaux et les mesures relatives à l'hygiène des pâtures ne sont que rarement prises en compte dans la planification des mesures de contrôle des parasitoses, il en résulte un schéma de traitement de routine basé sur 3 à 4 traitements par année, ce qui représente un usage d'anthelminthiques souvent supérieur à la nécessité. Vu le développement continu de populations de cyatostomes résistants aux anthelminthiques, un changement de stratégie dans le contrôle des helminthes est nécessaire. Le contrôle sélectif propagé par les parasitologues et les cliniciens des deux sites de la faculté Vetsuisse propose de seulement traiter les chevaux sains adultes (> de 4 ans) si l'excrétion des œufs de strongles dépasse 200 œufs par gramme de selles. Une différentiation régulière des populations de strongles, le contrôle de l'efficacité des anthelminthiques et des mesures de quarantaines chez les nouveaux venus sont des composants indispensables de ce concept. Les expériences faites jusqu'à présent avec cette stratégie dans plusieurs exploitations-pilotes montrent que seulement 4 % des analyses coprologiques sont suivies par une application d'anthelminthiques. Pour les chevaux qui n'ont pas été vermifugés pendant toute la saison, un traitement de sécurité à la fin de la saison de pâturage est recommandé.

Investigation of sainfoin (Onobrychis viciifolia) cultivar differences on nitrogen balance and fecal egg count in artificially infected lambs.

Research in ruminant nutrition and helminth control with forages, which contain condensed tannins (CT), suggests that varying responses may depend not only on CT concentration but also on CT composition. An experiment was designed to test this by feeding 2 dried sainfoin cultivars (Visnovsky and Perly), which differed in CT properties, to lambs that were artificially infected with the abomasal blood-sucking nematode Haemonchus contortus. Twenty-four infected lambs received 1 of these 2 cultivars; the feeds were either untreated or treated with the CT-binding polyethylene glycol over 4 wk (n = 6). The 2 cultivars were also fed to 2 × 6 uninfected lambs. Nutrient digestibility, N balance, ADG, plasma urea, together with indicators of infection [fecal egg count (FEC), abomasal worm count, per capita female fecundity, erythrocytic indices, and serum protein], were determined. The specific effects of sainfoin cultivar, CT, and infection were evaluated by contrast analysis. Digestibility of both NDF and ADF were less (P < 0.001) with Perly compared with Visnovsky. The apparent nutrient digestibility was reduced (P < 0.001) by CT. However, no clear cultivar effects were evident on N excretion and retention. Condensed tannins reduced (P = 0.05) body N retention and shifted (P < 0.001) N excretion from urine to feces. Unlike cultivar and CT, infection decreased (P = 0.002) ADG. Plasma urea concentration was decreased (P = 0.007) in Perly- compared with Visnovsky-fed lambs and was decreased (P < 0.001) by CT. Plasma concentrations of essential and semiessential AA were increased (P < 0.001) by CT. The groups of infected lambs did not clearly differ in abomasal worm counts and erythrocytic indicators. In the last 2 to 3 wk of the experiment, FEC was decreased (P ≤ 0.01) when feeding CT. The lack of substantial cultivar effects suggests that the differences in CT properties may have been too small to result in nutritional and anthelmintic effects. The present results indicate that sainfoin CT had a mitigating effect on FEC and, consequently, pasture infectivity. However, the reduction was too small to expect any significant benefits in an Haemonchus-dominated system. Therefore, the use of sainfoin for controlling H. contortus should only be one component within an integrated worm control system.

Nitrogen and mineral balance of lambs artificially infected with Haemonchus contortus and fed tanniferous sainfoin (Onobrychis viciifolia).

Tanniferous temperate legumes are assumed to possess anthelmintic properties, but it is unclear whether this is the direct result of condensed tannins (CT) or is mediated indirectly via an improved metabolic protein supply. A metabolism experiment was conducted to differentiate between these factors by feeding the CT plant sainfoin (19.7% CP in DM) to lambs infected with the abomasal blood-sucking nematode Hemonchus contortus. A total of 18 infected lambs were fed sainfoin either untreated or treated with polyethylene glycol, a CT-inactivating agent, or a grass-clover mixture (13.2% CP in DM) over 3 wk (n = 6). Six uninfected lambs received the grass-clover mixture as a control. In addition to indicators of infection (fecal egg count, packed-cell volume, abomasal worm burden, and serum protein), nutrient digestibility, the balance of N and selected minerals, ruminal fluid characteristics, and plasma AA levels were determined mostly in the final experimental week. The specific effects of the sainfoin CT, the extra CP with sainfoin, and the infection were statistically evaluated by contrast analysis. The sainfoin CT exerted no beneficial effects on resilience to nematode infection and exerted only minor effects on ruminal ammonia or blood urea concentrations and the excretory pattern of N. Plasma alanine, aspartate, and proline concentrations tended to be greater (P < or = 0.09) because of the sainfoin CT, whereas the other AA remained unaffected. Intake of the mineral supplement was lower (P < 0.001) for lambs fed sainfoin compared with those fed sainfoin treated with polyethylene glycol. Feeding the high-protein sainfoin instead of the grass-clover mixture increased (P < 0.001) N retention and apparent OM digestibility, whereas digestibility of NDF and ADF were decreased (P < 0.001). Feeding sainfoin also decreased (P < or = 0.04) plasma alanine, glycine, isoleucine, and total nonessential AA compared with the grass-clover mixture. Although fecal egg count, worm burden, and packed cell volume were not affected by the greater CP supply associated with sainfoin feeding, serum albumin level was increased (P = 0.008). The lack of effects of sainfoin on resilience to nematode infection might have been the result of the unexpectedly low CT content (3.6% in DM) of the material used. It cannot be excluded that longer term feeding of this batch of sainfoin might have been effective.

Case-control study to identify risk factors for bovine cysticercosis on farms in Switzerland.

Taenia saginata cysticercosis causes financial losses to the beef industry and farmers, and represents a significant source for human infection in many countries. A case-control study was conducted to identify risk factors for bovine cysticercosis on farms in Switzerland. The case group (n=119) consisted of farms with infected cattle identified at slaughter in 2005 and 2006. Infections were confirmed by morphological or molecular diagnosis. The control group (n=66) comprised randomly selected farms with cattle slaughtered in the same period but with no evidence or history of infection. In personal structured interviews with the farmers, information regarding local surroundings and farm management was collected. Logistic regression revealed the following 5 factors as being positively associated with the occurrence of bovine cysticercosis: the presence of a railway line or a car park close to areas grazed by cattle, leisure activities around these areas, use of purchased roughage and organized public activities on farms attracting visitors. This information is considered useful for government authorities to direct control strategies as well as for farmers to take measures tailored to local situations.

Failure of Duddingtonia flagrans to reduce gastrointestinal nematode infections in dairy ewes.

A field study was conducted on three Swiss farms to investigate the efficacy of Duddingtonia flagrans against naturally acquired infections of gastrointestinal nematodes in adult dairy sheep. On each farm the ewes were divided into two equal groups. One group received Duddingtonia during a period of 4 months at a daily dose rate of 10(6) chlamydospores per kilogram body weight, the second group acted as controls. At an overall moderate infection level in all farms D. flagrans did not have a significant effect on the observed parasitological parameters with the exception of a significantly reduced herbage infectivity in one farm. In contrast, the results from faecal cultures indicated a mean suppression of larval development during the fungus-feeding period between 82, 89 and 93% on the three farms, respectively. The discrepancy observed between the fungus efficacy in coprocultures and on pasture, which was also observed in several other studies deserves further research.

Avermectin-resistance in gastrointestinal nematodes of Boer goats and Dorper sheep in Switzerland.

Anthelmintic resistance in gastrointestinal nematodes among small ruminants is widespread in South Africa and Dorper sheep and Boer goats have been imported into Switzerland from this country on a number of occasions. Therefore, this study aimed to investigate the occurrence of avermectin (AVM) resistant gastrointestinal nematodes (GIN) in these breeds in Switzerland. A total of 24 Boer goat farms and 12 Dorper sheep farms participated in the study. According to the faecal egg count reduction test (FECRT) AVM-resistant GIN populations were confirmed in 7 of the 24 Boer goat farms and suspected in a further 8 farms. Likewise AVM-resistance was confirmed in 2 of 12 Dorper sheep farms and suspected in a further 6 farms. Haemonchus contortus and Trichostrongylus spp. were the dominant resistant species according to larval cultures. In the farms with detected AVM-resistance the animals were additionally treated with levamisole after natural reinfection. With the exception of one farm with a 'close-to cutoff-result' the FECRT gave no indication for resistance against levamisole. The results indicate that AVM-resistance is widespread in Swiss small ruminant farms keeping Boer goats and Dorper sheep. The common tradition of grazing animals from different farms on prealpine and alpine pastures could favour the spread of resistant populations within the country.

[Overview of helminth problems in domestic ruminants in Switzerland]. / Problematik des Helminthenbefalls bei Hauswiederkäuern in der Schweiz: Aktuelle Perspektiven.

Potent anthelmintics were introduced into the Swiss market several decades ago. Despite this, gastrointestinal nematodes (GIN), lungworms and the large liver fluke (Fasciola hepatica) can successfully inhabit Swiss ruminant farms. This is mainly due to a high reproductive capacity as well as very efficient survival strategies. In addition some species readily develop anthelmintic resistance. GIN-infections in young cattle are under comparatively good control. However, prophylactic measures are compromised where adult stock is also affected due to incomplete development of immune protection. Under these circumstances control measures must include all age groups. This results in fewer helminths in refugia thus may accelerate the development of anthelmintic resistance. This review aims to present a synopsis of the significance of the major helminth infections obtained on pasture by large and small ruminants in Switzerland. Currently available strategies for strategic helminth control are summarized and an outlook is given on new developments which might expand the spectrum of control measures relevant for veterinary practice in the future.

In vitro screening of six anthelmintic plant products against larval Haemonchus contortus with a modified methyl-thiazolyl-tetrazolium reduction assay.

Because of the increasing anthelmintic resistance and the impact of conventional anthelmintics on the environment, it is important to look for alternative strategies against gastrointestinal nematodes. Phytotherapy could be one of the major options to control these pathologies. Extracts or ingredients of six different plant species were tested against exsheathed infective larvae of Haemonchus contortus using a modified methyl-thiazolyl-tetrazolium (MTT) reduction assay. Pyrantel tartrate was used as reference anthelmintic. Bromelain, the enzyme complex of the stem of Ananas comosus (Bromeliaceae), the ethanolic extracts of seeds of Azadirachta indica (Meliaceae), Caesalpinia crista (Caesalpiniaceae) and Vernonia anthelmintica (Asteraceae), and the ethanolic extracts of the whole plant of Fumaria parviflora (Papaveraceae) and of the fruit of Embelia ribes (Myrsinaceae) showed an anthelmintic efficacy of up to 93%, relative to pyrantel tartrate. Based on these results obtained with larval Haemonchus contortus, the modified MTT reduction assay could be a possible method for testing plant products with anthelmintic properties.

[Cerebrospinal nematodosis in sheep in Switzerland]. / Zerebrospinale Nematodose beim Schaf in der Schweiz.

In December 2005 three sheep, originating from Canton Tessin, were presented with cerebrospinal nematodosis. The animals had a history of progressive pelvic limb ataxia and recumbency. The most important clinical findings were an abnormal gait (wide stance, pelvic limb paresis) and decreased sensitivity of the pelvic limbs. The general condition was slightly or moderately disturbed, appetite was normal. Examination of the cerebrospinal fluid revealed mononuclear cells and eosinophils, suggesting a helminthic infection of the central nervous system. Postmortem findings confirmed the clinical diagnosis in one animal as parts of a nematode were found in the thoracic spinal cord. Even though the nematode could not be identified, infection with Elaphostrongylus cervi seems very likely, as the sheep are in close contact with deer on the pastures and the parasite is known to infect goats in Switzerland. This is the first description of cerebrospinal nematodosis in sheep in Switzerland.

[Equine strongyles. I. Development of anthelmintic resistance]. / Strongyliden beim Pferd. I. Resistenzentwicklung gegen Anthelminthika.

Small strongyles (cyathostomes) that are resistant against anthelmintics have become a major problem in equine medicine in the recent years. In many European countries benzimidazole-resistant cyathostomes are widespread and are now present in well over 50% of equine populations investigated. In contrast, resistance against ivermectin has not been reported despite its widespread use in the recent years. Optimising the frequency of treatments based on quantitative faecal monitoring is of great importance to preserve remaining anthelmintic efficacy.

[Equine strongyles II. Occurrence of anthelmintic resistance in Switzerland]. / Strongyliden beim Pferd. II. Vorkommen von Anthelminthika-Resistenzen in der Schweiz.

The occurrence of anthelmintic resistance in strongyles was investigated in 440 horses on 90 farms in Switzerland. The egg hatch assay suggested that benzimidazole (BZ)-resistance was present in 40 of 82 farms (49%). Faecal egg count reduction after pyrantel-treatment was above 96% in 14 of 15 farms. In the remaining farm the efficacy was only 80%. Ivermectin efficacy was investigated on 5 farms and the efficacy was recorded at 98-100%. Faecal cultures undertaken after treatment revealed almost exclusively larvae of the family Cyathostominae. Data about management practices, pasture hygiene and anthelmintic usage were obtained with a questionnaire. Horses were treated on average 3.5 times per year. In 75% of the farms BZ were a component of the seasonal treatment schedule. Only the use of BZ had a significant correlation with the presence of BZ-resistance (P < 0.01). Recommendations for the control of equine strongyles should include measures that minimize the risk of resistance developing against remaining effective anthelmintics.

Multiple anthelmintic resistance in Haemonchus contortus isolated from South African Boer goats in Switzerland.

A suspected case of multiple anthelmintic resistance on a farm in the canton of Zurich, Switzerland, into which South African Boer goats had previously been imported, was confirmed in a controlled test. Twenty sheep were allocated into one control group and three treatment groups to determine the efficacy of mebendazole, ivermectin and moxidectin applying the faecal egg count reduction test (FECRT). The sheep were slaughtered 1 week later and post-mortem worm counts were performed. Benzimidazole and ivermectin resistance were found in Haemonchus contortus with an efficacy of 55 and 61%, respectively. Moxidectin appeared to be effective when the data was analysed according to the recommended analytical techniques with an efficacy of 96%. This is the first description of resistance of gastrointestinal nematodes to one of the macrocyclic lactones in small ruminants in Switzerland. The results are discussed in relation to the importance of controlling livestock before importation.

Detection of anthelmintic resistance: a comparison of mathematical techniques.

Anthelmintic resistance has become an increasing problem particularly to gastrointestinal tract nematodes and appropriate methods are required to detect this phenomenon so the correct action can be taken. This paper compares a number of mathematical techniques that are used to analyse data. The negative binomial distribution is a mathematical distribution used to model aggregated data and hence is suitable to model the intensity of parasite burden and the magnitude of the faecal egg counts. Maximum likelihood techniques are utilised to exploit this mathematical distribution to analyse the magnitude of the faecal egg count reduction and decline in the worm burden in response to anthelmintic treatment. Data from experimental groups of sheep described in the accompanying paper are used. In addition, simulated data sets of faecal egg counts were created using a random number generator following appropriate negative binomial distributions. The results demonstrate this statistical model can detect evidence of anthelmintic resistance with a faecal egg reduction test that otherwise might require a slaughter trial to demonstrate. In addition, the simulated data sets confirm that there is a significant probability of failure to detect low anthelmintic efficacy with commonly used mathematical techniques. Consequently, the use of maximum likelihood mathematical techniques with a negative binomial statistical model would aid in the early detection of anthelmintic resistance using faecal egg count reductions and result in a lower probability of inappropriately assigning an anthelmintic as effective.

[Animal health in organic agriculture: new guidelines and perspectives for food animal practitioners]. / Tiergesundheit im biologischen Landbau: Neue Richtlinien und Perspektiven für die Nutztierpraxis.

In the last decade, the organic agriculture in Switzerland has been substantially increased due to the interest of consumer and financial incentives of the federation. Ruminants take directly or indirectly the largest part from grassland used within the organic managed surfaces. As the contacts between veterinary practice and organic agriculture has increased, the potential for veterinary activity in this area has developed considerably. The organic agriculture guidelines stipulate that all the preventive measures should be taken in feeding, keeping and breeding to insure animal health safety. This requires veterinary services for herd management. The organic status of a farm affects veterinary practice also in the form of alternative therapy/drugs administration and measures like dehorning and tail-docking. An important point in organic managed herds requests that treatment of animals should depend on alternative medical preparations or procedures based on veterinarian's experience and also on the therapeutic effect on the animal species concerned as well as on the disease. However, there are no restrictions on the veterinarian to use registered drugs as long as no alternative therapy, according to experience and possible success, is available to treat the animals. The prophylactic administration of allopathic veterinary drugs is not permissible. Further features in organic farms regarding the use of drugs are the keeping of withholding/withdrawal time, the documentation and the treatment frequency tolerated by organic marketing. Despite the above measures, the animal health has a priority regardless of its organic status. Although management of organic farms represent a unique responsibility, there are still obvious deficits in the education of veterinary practitioners for this new situation. However, in the future the extension of veterinary activity to include the alternative medical therapy should be regarded for the practitioner as a challenge and an opportunity at the same time.