Topic:Anthelmintic Treatment
Anthelmintic treatment involves the use of drugs to control parasitic worm infections in horses. These treatments target various types of internal parasites, such as strongyles, ascarids, and tapeworms, which can affect equine health and performance. The administration of anthelmintics is a common practice in equine management to reduce parasite burdens and minimize the risk of disease transmission. Different classes of anthelmintics, including benzimidazoles, macrocyclic lactones, and pyrantel, are used based on the specific parasitic threats and resistance patterns. This page compiles peer-reviewed research studies and scholarly articles that explore the efficacy, resistance development, and management strategies associated with anthelmintic treatment in horses.
Prevalence of infestation with gastrointestinal nematodes in Pony Club horses in Victoria. The aims of the present study were to identify the common gastrointestinal nematodes, to assess the prevalence of infestation with gastrointestinal nematodes, and to assess some potential indirect determinants of nematode parasitism in Victorian Pony Club horses. Methods: A total of 106 horses from five Pony Clubs from outer Melbourne and Geelong, Victoria, Australia, were enrolled in a cross-sectional study. Fresh faecal samples were collected and faecal egg counts (FECs) performed on site within 2 h of collection. Potential determinants of the FEC were analysed using logistic and negative bi...
Helminth egg excretion with regard to age, gender and management practices on UK Thoroughbred studs. Few studies have described the combined effect of age, gender, management and control programmes on helminth prevalence and egg shedding in grazing equines. Here, fecal samples collected from 1221 Thoroughbred horses, residing at 22 studs in the UK, were analysed. The distribution of strongyle eggs amongst individuals in relation to age, gender and management practices was investigated. Fecal worm egg counts (FWECs), described as the number of eggs per gramme (epg) of feces, were determined using a modification of the salt flotation method. The FWEC prevalence (mean%) of strongyles, Parascaris...
Lack of Cyathostomin sp. reduction after anthelmintic treatment in horses in Brazil. The increase of anthelmintic resistance in the last years in the nematode population of veterinary importance has become a major concern. The objective of the present study was to evaluate the efficacy of the main anthelmintic drugs available in the market against small strongyles of horses in Brazil. A total of 498 horses from 11 horse farms, located in the states of Paraná, São Paulo, Rio de Janeiro and Minas Gerais, in Brazil, were treated with ivermectin, moxidectin, pyrantel and fenbendazole, orally at their recommended doses. The fecal egg count reduction test (FECRT) was used to deter...
[Strongylids (Nematoda: Strongylidae) of domestic horses in Ukraine: modern state of Fauna and structure of the parasite community]. Species composition and structure of the strongylid community was studies on helminthological material collected from 162 domestic horses from 11 regions of Ukraine by the in vivo method. Animals were treated with anthelmintic drug "Univerm" (0.2% aversectin C, Russia). Faecal samples (200 g each) were collected from every horse at 24, 36, 48 and 60 hours after treatment; all nematodes expelled (90.851 specimens) were collected and identified. Thirty-three strongylid species from 12 genera (8 species of subfamily Strongylinae and 25--of Cyathostominae) were found in domestic horses in Ukraine....
Real-time PCR evaluation of Strongylus vulgaris in horses on farms in Denmark and Central Kentucky. Strongyle parasites are ubiquitous in grazing horses, and the large strongyle Strongylus vulgaris is considered the most pathogenic helminth parasite of horses. Recent investigations have suggested an association between occurrence of this parasite and usage of selective therapy based on regular fecal egg counts. The established diagnostic method for S. vulgaris involves larval culture and subsequent morphological identification of third stage larvae under the microscope. Recently, a real-time PCR assay was developed and validated for the detection and semi-quantification of S. vulgaris eggs i...
Anthelmintic metabolism in parasitic helminths: proteomic insights. Anthelmintics are the cornerstone of parasitic helminth control. Surprisingly, understanding of the biochemical pathways used by parasitic helminths to detoxify anthelmintics is fragmented, despite the increasing global threat of anthelmintic resistance within the ruminant and equine industries. Reductionist biochemistry has likely over-estimated the enzymatic role of glutathione transferases in anthelmintic metabolism and neglected the potential role of the cytochrome P-450 superfamily (CYPs). Proteomic technologies offers the opportunity to support genomics, reverse genetics and pharmacokine...
Strongylus vulgaris associated with usage of selective therapy on Danish horse farms-is it reemerging? Nematodes belonging to the order Strongylida are ubiquitous in grazing horses, and the large strongyle Strongylus vulgaris is considered the most pathogenic. This parasite was originally described widely prevalent in equine establishments, but decades of frequent anthelmintic treatment appears to have reduced the prevalence dramatically. Increasing levels of anthelmintic resistance in cyathostomin parasites have led to implementation of selective therapy to reduce further development of resistance. It has been hypothesized that S. vulgaris could reoccur under these less intensive treatment cir...
Comparative performance of macrocyclic lactones against large strongyles in horses. Several formulations of macrocyclic lactones (abamectin, ivermectin, moxidectin), including ivermectin combined with pyrantel (tetrahydropyrimidine) and ivermectin combined with praziquantel (pyrazinoisoquinolin derivative), were tested regarding their efficacy to control gastrointestinal nematodes of horses on a stud farm in southern Brazil. In addition, we tested a pharmaceutically produced generic paste containing ivermectin 4%. Similar formulations of avermectins had different efficacies measured by reduction of EPG. Levels of efficacy of the tested drugs varied against Strongylus edentatu...
Efficacy of major anthelmintics against horse cyathostomins in France. This paper reports a survey conducted in France during 2011 to evaluate the efficacy of commonly used anthelmintics against horse cyathostomins. A total of 40 farms and 1089 horses were screened for the presence of cyathostomins. All farms but one were positive, with an overall animal infection rate of 53.7%, ranging from 9% to 83% on individual farms. On 445 horses from 30 of these farms, a faecal egg count reduction test (FECRT) was performed to evaluate the efficacy of oral formulations of fenbendazole (FBZ), pyrantel embonate (PYR), ivermectin (IVM) and moxidectin (MOX). Calculation of the...
Investigation of strongyle EPG values in horse mares relative to known age, number positive, and level of egg shedding in field studies on 26 farms in Central Kentucky (2010-2011). A parasite study was done in 1,300 horse mares on 26 farms in Central Kentucky over a 5-month period in 2010 and 2011. The mares included 1,114 Thoroughbreds (TB) on 24 farms, 64 Standardbreds (SB) on 1 farm, and 122 mixed light horse types (MLH) on 1 farm. The objective of this research was to determine strongyle eggs per gram of feces (EPG) counts for evaluation by known age, number positive, and level of egg shedding by the mares. This was done to establish strongyle EPG profiles for the mares to aid in determining whether antiparasitic treatment was necessary. Eggs found were considered th...
An inconvenient truth: global worming and anthelmintic resistance. Over the past 10-15 years, we have witnessed a rapid increase in both the prevalence and magnitude of anthelmintic resistance, and this increase appears to be a worldwide phenomenon. Reports of anthelmintic resistance to multiple drugs in individual parasite species, and in multiple parasite species across virtually all livestock hosts, are increasingly common. In addition, since the introduction of ivermectin in 1981, no novel anthelmintic classes were developed and introduced for use in livestock until recently with the launch of monepantel in New Zealand. Thus, livestock producers are often...
Anthelmintic resistance in non-strongylid parasites of horses. Since 2002, selected populations of Parascaris equorum in several countries have been reported to survive treatment with macrocyclic lactone (M/L) anthelmintics. Clinical treatment failures are characterized by negligible fecal egg count reduction, but M/L resistance has been confirmed in ascarids by controlled efficacy testing. Resistance was selected by current parasite control practices for foals, which often include exclusive and excessively frequent use of M/L dewormers, thereby minimizing refugia within the host and in the environment. Chemical control of M/L-resistant isolates can be ac...
Resistance to avermectin/milbemycin anthelmintics in equine cyathostomins – current situation. Avermectins and milbemycins (AM) are potent compounds against all major nematode parasites, but their continuous usage has led to the development of widespread resistance in many of the important species of ruminant and equine parasites. The exception to this has been the cyathostomins, where AM resistance was recently first reported only after decades of drug exposure. Data from a Brazilian study suggests that AM resistance has developed in cyathostomins and reports of shortened egg reappearance periods after ivermectin treatment have been published recently from USA and Germany. Thus, AM res...
Anthelmintic resistance in equine parasites – detection, potential clinical relevance and implications for control. During the past two decades anthelmintic resistance in equine parasites has been found in the group of small strongyle species (cyathostomins) and in the ascarid species Parascaris equorum. The ubiquitous nature and possible severe consequences of disease with these nematodes make them the prime targets of current worm control programmes. Traditional control strategies mainly rely on the strategic application of anthelmintics, currently represented by three major drug classes: benzimidazoles (BZ), the tetrahydropyrimidine pyrantel (PYR) and macrocyclic lactones (ML). Following decades of routi...
Searching for ivermectin resistance in Dutch horses. A study was conducted to evaluate the occurrence of resistance against, in particular, ivermectin in cyathostomins in the Netherlands. Seventy horse farms were visited between October 2007 and November 2009. In initial screening, faecal samples were collected 2 weeks after deworming with either ivermectin, moxidectin or doramectin. Pooled faecal samples from a maximum of 10 horses were examined for worm eggs using a modified McMaster technique and for worm larvae after faecal larval cultures. In total 931 horses were involved. On 15 of 70 farms eggs and/or larvae were found. On 8 of these 15 f...
Strongylus vulgaris (Looss, 1900) in horses in Italy: is it still a problem? A post-mortem survey was carried out on 46 Sardinian horses to evaluate the presence of Strongylus vulgaris and associated pathology. Horses were from local farms and had been treated with broad-spectrum anthelmintics at least 3 times a year. Examination of the cranial mesenteric arterial system (CMAS) showed parasite-induced lesions in all horses. S. vulgaris larvae were found in 39% of examined arteries, while their detection rate in coprocultures was 4%. Histology, carried out on 26 horses, showed mainly chronic and chronic-active lesions. Histometry showed a significant increase in thickne...
Strongyle egg counts in Standardbred trotters: are they associated with race performance? Strongyle worm burdens are assumed to subclinically affect equine performance. This assumption appears to be particularly pronounced in the equine racing industry. Objective: Race results of Standardbred trotters are negatively affected by high strongyle faecal egg count levels. Methods: Faecal samples were obtained from 213 racing Standardbred trotters, aged ≥ 2 years, and stabled at training facilities of 21 professional trainers with license at racecourses in Denmark. Strongyle egg counts were generated using a McMaster technique. Race results were recorded as the finishing position of th...
An update on cyathostomins: anthelmintic resistance and diagnostic tools. Cyathostomins represent a potential cause of equine morbidity and have become the main focus of endoparasite control in managed horses. All grazing horses are at risk of infection with cyathostomins; therefore, the application of appropriate management measures is essential. Anthelmintics currently comprise the main method of control for equine nematodes and the ready availability of these products in some countries has resulted in their use becoming dissociated from veterinary involvement. This is concerning given the levels of anthelmintic resistance that have been recorded in cyathostomin p...
Impaired efficacy of ivermectin against Parascaris equorum, and both ivermectin and pyrantel against strongyle infections in trotter foals in Finland. In order to assess the resistance situation against macrocyclic lactones in Parascaris equorum and against tetrahydropyrimidine derivatives in strongyles in Finnish trotter horses, 112 foals on 18 farms, mostly 1 year old, were examined for these parasites with a modified McMaster faecal flotation method. P. equorum positive foals (n=24) were given ivermectin orally at a dose of 200 μg/kg b.w., while strongyle positive but P. equorum negative foals (n=38) received pyrantel embonate orally at a dose of 19 mg/kg. Sixteen P. equorum infected foals, treated with ivermectin, also harboured strongy...
Facing the threat of equine parasitic disease. Horses worldwide are exposed to a complex mixture of intestinal parasitic helminths. When burdens are high, these parasites can seriously compromise health and welfare. Some helminth species have an extremely high prevalence and are difficult to control, not least because there is a limited understanding of their most basic biology. Furthermore, levels of resistance to some of the commonly used anthelmintics are widespread and increasing. The cyathostomins are the most common nematode species affecting equids worldwide. Within this group of parasites are more than 50 different species. Until r...
A questionnaire survey on helminth control on horse farms in Brandenburg, Germany and the assessment of risks caused by different kinds of management. Control strategies for horse helminths are controversially discussed, and no ideal strategy exists. Presently, the spreading of anthelmintic resistance against all three classes of anthelmintics is of special concern. Advice on how to slow the development of anthelmintic resistance does not seem to have reached the majority of horse owners yet. In our study, we wanted to capture the current standard of helminth control and to analyse the effectiveness of these control strategies. Seven hundred horse farms in Brandenburg, Germany were sent a questionnaire in June/July 2006 asking various questi...
β-Tubulin genotypes in six species of cyathostomins from anthelmintic-naive Przewalski and benzimidazole-resistant brood horses in Ukraine. Resistance to benzimidazoles (BZ) in the gastrointestinal nematodes of livestock is characterised by the presence of specific polymorphisms in the β-tubulin isotype 1 protein, a component of microtubules. The most prevalent polymorphism associated with resistance in nematodes infecting cattle, sheep, and goats is found at codon 200, with minor occurrences of polymorphisms at codons 167 and 198. In the cyathostomins that infect horses, however, a polymorphism at codon 167 appears to be more common than the codon 200 polymorphism. In the present study, a focussed analysis of PCR-amplified β-tu...
Equine anthelmintics: survey of the patterns of use, beliefs and attitudes among horse owners in the UK. An online survey was conducted to establish horse owners' beliefs, attitudes and practices relating to the use of anthelmintic drugs. Out of a total of 574 respondents, 89 per cent described themselves as 'leisure riders', most of whom took part in a variety of activities including eventing, show jumping, dressage, hunter trials, hunting, driving, endurance and showing. Overall, respondents were generally aware and concerned about the issue of anthelmintic resistance. Less than 60 per cent of all respondents were comfortable with their existing anthelmintic programme, and 25 per cent would lik...
Further evaluation in field tests of the activity of three anthelmintics (fenbendazole, oxibendazole, and pyrantel pamoate) against the ascarid Parascaris equorum in horse foals on eight farms in Central Kentucky (2009-2010). The activity of three anthelmintics (fenbendazole-FBZ; oxibendazole-OBZ; and pyrantel pamoate-PRT) was ascertained against the ascarid Parascaris equorum in horse foals on eight farms in Central Kentucky (2009-2010) in field tests. A total of 316 foals were treated, and 168 (53.2%) were passing ascarid eggs on the day of treatment. Evaluation of drug efficacy was determined qualitatively by comparing the number of foals passing ascarid eggs in their feces before and after treatment. The main purpose was to obtain data on current activity of these compounds against ascarids. Additionally, the o...
Prevalence of strongyles and efficacy of fenbendazole and ivermectin in working horses in El Sauce, Nicaragua. Horses, mules and donkeys are indispensable farming and working animals in many developing countries, and their health status is important to the farmers. Strongyle parasites are ubiquitous in grazing horses world-wide and are known to constitute a threat to equine health. This study determined the prevalence of strongyle infection, the efficacy of ivermectin and fenbendazole treatment, and strongyle re-infection rates of working horses during the dry months in Nicaragua. One hundred and five horses used by farmers for transport of people and goods were randomly allocated into three treatment ...
Prevalence of helminths in horses in the state of Brandenburg, Germany. The objective of the study was to estimate the prevalence of helminths in the horse population of the state of Brandenburg, Germany. One hundred and twenty-six horse farms in the state were selected by randomised stratified sampling. In total, 1,407 horses across all farms were examined coproscopically. The experimental unit was the horse farm: a farm was considered infected when at least one horse on the farm investigated was positive for helminth eggs. Animal details such as age, breed and sex were collected for all study horses and analysed for risk of infection. Risk was defined as horses ...
Reduced activity of moxidectin and ivermectin on small strongyles in young horses on a farm (BC) in Central Kentucky in two field tests with notes on variable counts of eggs per gram of feces (EPGs). Two field tests (A and B) were conducted in Thoroughbred weanlings born in 2008 and 2009 on a farm (BC) in Central Kentucky. The purpose was to determine the current efficacy of moxidectin (MOX) and ivermectin (IVM) on small strongyles by pre- and posttreatment counts of eggs per gram of feces (EPGs) in this geographical area. In previous parasite studies in horses on this farm and in horses on numerous other farms in this area, cultures of feces indicated the strongyle larvae were all small strongyles. Therefore, the strongyle eggs in the EPG counts are considered small strongyles. Designatio...
A randomized triple blind trial to assess the effect of an anthelmintic programme for working equids in Morocco. Gastro-intestinal parasitism has been identified as a significant cause of disease in working equids in many countries. This randomized triple-blind trial was designed to assess the impact of an anthelmintic treatment programme (using oral ivermectin and fenbendazole) comparing treated and placebo control populations of working donkeys, mules and horses in field conditions in Morocco. In particular, we assessed animal body weight and condition score, together with a questionnaire-based owner evaluation of number of subjective animal health parameters. Faecal worm egg count was also measured. R...
[The efficacy of anthelmintic drugs against horse strongyles in the area of Salzburg and preliminary results of selective anthelmintic treatment]. In recent years more and more cases of anthelmintic resistant equine strongyles were reported. The latest developments are cases of resistance against macrocyclic lactones. In order to delay this process less anthelmintics and only those which have been previously tested for their efficacy on each individual farm should be used. During the grazing season 2008 faecal samples of 281 horses and 5 donkeys from 26 farms were analysed in the area of Salzburg. To 164 of these horses selective anthelmintic treatment was implemented. Every four weeks faecal samples from the 164 horses were quantitative...