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Topic:Anthelmintic Resistance
Anthelmintic resistance in horses refers to the reduced effectiveness of deworming agents, known as anthelmintics, in controlling parasitic worm populations. This phenomenon arises when parasites develop the ability to survive treatments that previously were effective at standard doses. Anthelmintic resistance is a growing concern in equine management, as it can lead to increased parasite burdens and associated health issues in horses. Common parasites affected by resistance include small strongyles (cyathostomins) and ascarids (Parascaris spp.). This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, prevalence, and management strategies related to anthelmintic resistance in equine populations.
Prevalence of anthelmintic resistant cyathostomins in Prince Edward Island, Canada. Cyathostomins are the most common parasites of adult horses worldwide. Currently, the three classes of anthelmintics used to treat cyathostomin infections includes benzimidazoles, pyrimidines and macrocyclic lactones. However, due to widespread overuse, cyathostomins have developed varying degrees of resistance to all classes of anthelmintics. Fecal egg count reduction tests (FECRT) are currently used to determine the presence of anthelmintic resistance (AR), while egg reappearance periods (ERP) are used to investigate early macrocyclic lactone resistance. The objective of this study was to in...
Three-year study to evaluate an anthelmintic treatment regimen with reduced treatment frequency in horses on two study sites in Belgium. In the present study, an anthelmintic treatment regimen with reduced treatment frequency was evaluated in horses on two study sites in Belgium during three consecutive summer pasture seasons. Historically, the horses on both study sites were treated up to 6 times a year with ivermectin (IVM) or up to 4 times a year with moxidectin (MOX), and previous efficacy evaluations indicated a reduced egg reappearance period in some of the treated horses for both IVM (28 days) and MOX (42 days). In the present study, all horses were treated with IVM or MOX in the spring and in autumn. Faecal egg counts (...
Spread of anthelmintic resistance in intestinal helminths of dogs and cats is currently less pronounced than in ruminants and horses – Yet it is of major concern. Anthelmintic resistance (AR) has thus far only rarely been reported for intestinal helminths of dogs and cats, in contrast to parasites of livestock and horses. We highlight possible reasons for this striking and important discrepancy, including ecological, biological and genetic factors and/or intervention regimens of key intestinal helminths concerning both host groups. In view of the current knowledge related to the genetics, mechanisms and principles of AR development, we point at issues which in our view contribute to a comparatively lower risk of AR development in intestinal helminths of...
Constitutive and differential expression of transport protein genes in Parascaris univalens larvae and adult tissues after in vitro exposure to anthelmintic drugs. The equine roundworm Parascaris univalens has developed resistance to the three anthelmintic substances most commonly used in horses. The mechanisms responsible for resistance are believed to be multi-genic, and transport proteins such as the P-glycoprotein (Pgp) family have been suggested to be involved in resistance in several parasites including P. univlaens. To facilitate further research into the mechanisms behind drug metabolism and resistance development in P. univalens we aimed to develop an in vitro model based on larvae. We developed a fast and easy protocol for hatching P. univalens...
Ivermectin treatment in lactating mares results in suboptimal ivermectin exposure in their suckling foals. The management of equine strongyles has become problematic over the last decade because of an increased prevalence of drug-resistant isolates worldwide. Therapeutic options are therefore limited, leaving macrocyclic lactones as the most often effective drug class. However, their lipophilic properties result in a long-lasting elimination that could favour drug resistance selection. As a result, ivermectin treatment in lactating mares could promote suboptimal exposure of their foal parasites to ivermectin, thereby selecting for more resistant worms. To test for this putative transfer, we selecte...
Action of Carvacrol on Parascaris sp. and Antagonistic Effect on Nicotinic Acetylcholine Receptors. sp. is the only ascarid parasitic nematode in equids and one of the most threatening infectious organisms in horses. Only a limited number of compounds are available for treatment of horse helminthiasis, and sp. worms have developed resistance to the three major anthelmintic families. In order to overcome the appearance of resistance, there is an urgent need for new therapeutic strategies. The active ingredients of herbal essential oils are potentially effective antiparasitic drugs. Carvacrol is one of the principal chemicals of essential oil from , , , , and herbs. However, the antiparasi...
The Use of Molecular Profiling to Track Equine Reinfection Rates of Cyathostomin Species Following Anthelmintic Administration. Cyathostomins are a multispecies parasite ubiquitous in Equids. Cyathostomins have developed resistance to all but one class of anthelmintics, but species-level sensitivity to anthelmintics has not been shown. This study measured reinfection rates of cyathostomin species following the administration of three commercial dewormers. Nine treated horses were compared with 90 untreated controls during June-September 2017-2019. Ivermectin (IVM) (n = 6), Moxidectin (MOX) (n = 8) or Pyrantel (PYR) (n = 8) were orally administered. Fecal samples were collected every 14 d for 98 d. Fecal egg count reduc...
Parascaris spp. eggs in horses of Italy: a large-scale epidemiological analysis of the egg excretion and conditioning factors. Equine ascariosis, caused by Parascaris spp., is a worldwide endoparasitic disease affecting young horses in particular. Despite the great number of horses reared in Italy, large-scale epidemiological surveys dealing with ascariosis prevalence in the country are not reported in the current literature. For this reason, the present survey aims to describe, for the first time, the spread and infestation of Parascaris spp. in a large population of Italian horses (6896 animals) using faecal egg counts, and further to identify risk factors associated with ascarid egg shedding. Methods: Individual re...
[New drugs for horses and production animals in 2020]. In 2020, one novel pharmaceutical agent for horses or food-producing animals was released on the German market, rendering the inhaled glucocorticoid ciclesonide (Aservo EquiHaler) available for horses for the first time. The authorization of one established veterinary active ingredient was extended to an additional species: The anthelmintic fenbendazole (Gallifen) from the benzimidazole group is now also authorized for pheasants. Additionally, 3 veterinary drugs with a new combination of active ingredients (ketoprofen + tilmicosin, ketoprofen + tulathromycin, prednisolone + lidoc...
Survey of anthelmintic resistance in a Romanian horse stud using three different methods. Resistance of cyathostomins to benzimidazole (BZ) anthelmintics is widespread in horses in many parts of the world. This study compared three methods for the determination of benzimidazole resistance of Cyathostominae in 18 horses from a stud farm in Romania. The horses were treated with Fenbendazole. The resistance test was performed by FECRT, ERP and PCR. On Day 0, larvae of species belonging to the Cyathostominae subfamily, types A, B, C, D and Gyalocephalus, as well as Strongylus vulgaris species of the Strongylinae subfamily, were identified. At 42 days post treatment with fenbendazole on...
Reduced Efficacy of Fenbendazole and Pyrantel Pamoate Treatments against Intestinal Nematodes of Stud and Performance Horses. Nematodes are an important cause of disease and loss of performance in horses. Changes in the parasitic fauna of horses have occurred in the past few decades, making cyathostomins the major parasites in adult horses, while large strongyles have become less prevalent. spp. remains the most important parasite infecting foals and weanlings. Anthelmintic resistance is highly prevalent in cyathostomins and spp. worldwide and it must be factored into treatment decisions. To assess anthelmintic efficacy in Northern Italy, we sampled 215 horses from 17 sport and horse-breeding farms. Fecal egg count...
Salivary Cortisol, Equine Characteristics, and Management Factors Associated With Strongyle-Type Egg Shedding of Ohio Horses. Identification of factors associated with parasite infestation in horses could reduce frequency of anthelmintic administration and slow development of anthelmintic resistance. The study aim was to evaluate management factors, equine characteristics, and equine salivary cortisol concentrations for association with strongyle-type egg shedding levels. As immunocompromised horses appear to be more susceptible to parasite infestation, it was hypothesized that salivary cortisol concentration could be associated with parasite egg shedding. Saliva and fecal samples were collected from 200 horses acros...
Helminth infections in Italian donkeys: Strongylus vulgaris more common than Dictyocaulus arnfieldi. Donkeys have been used as working animals for transport and farm activities worldwide. Recently, in European countries, there has been an increasing interest in donkeys due to their use as pets, onotherapy or milk production. During 2014-2016, a countrywide survey was conducted to determine prevalence and risk factors of principal helminth infections in 1775 donkeys in 77 Italian farms. A questionnaire on management and parasite control practices was filled out for each farm. Faecal samples were examined using a modified McMaster technique, a centrifugation/flotation method and a sedimentation...
Anthelmintic resistance of horse strongyle nematodes to ivermectin and pyrantel in Lithuania. With intensive use of anthelmintic drugs in recent decades, anthelmintic resistance (AR) in horse nematodes is becoming a growing issue in many countries. However, there is little available information about the parasites, treatment practices or AR in the horse population in Lithuania. The aim of this study was to assess the current situation of AR on horse farms in Lithuania. The study was conducted in 25 stables on horses with a strongyle faecal egg count (FEC) of ≥ 200 eggs per gram. A faecal egg count reduction test (FECRT) was performed on each farm after administration of ivermectin ...
Gastrointestinal Strongyles Egg Excretion in Relation to Age, Gender, and Management of Horses in Italy. Current equine helminth control strategies play a key role in strongyle epidemiology and anthelmintic resistance and have led to the recommendation for new treatment plans, which include diagnostic and efficacy surveillance. Assessing the equine strongyle distribution patterns would thus be useful and this study describes the strongyle prevalence in the equine population in Italy through coprological analysis and coproculture. In addition, individual data on each animal were collected in order to identify risk factors associated with strongyle egg shedding. Of the total number of stables inves...
Monitoring equine ascarid and cyathostomin parasites: Evaluating health parameters under different treatment regimens. Strongylid and ascarid parasites are omnipresent in equine stud farms, and ever-increasing levels of anthelmintic resistance are challenging the industry with finding more sustainable and yet effective parasite control programs. Objective: To evaluate egg count levels, bodyweight and equine health under defined parasite control protocols in foals and mares at two Standardbred and two Thoroughbred stud farms. Methods: Longitudinal randomised field trial. Methods: A total of 93 foals were enrolled and split into two treatment groups, and 99 mares were enrolled and assigned to three treatment gro...
Nutritional Supplements Containing Cardus mariano, Eucalyptus globulus, Gentiana lutea, Urtica urens, and Mallotus philippinensis Extracts Are Effective in Reducing Egg Shedding in Dairy Jennies (Equus asinus) Naturally Infected by Cyathostomins. The increasing levels of anthelmintic resistance together with the restrictions in the use of drugs in food producing animals have enforced the search for sustainable alternative approaches for parasite control. The current study aimed to investigate the safety and the efficacy of a commercially available phytotherapic formulation against gastrointestinal strongyles in donkeys. Twenty-two Ragusana jennies (2.6 ± 0.5 years old) were assigned to two equal groups. One group was treated with two doses of a phytotherapic supplement Paraxitebio® containing , and , 14 days apart (Group A). One grou...
Meta-analysis of cyathostomin species-specific prevalence and relative abundance in domestic horses from 1975-2020: emphasis on geographical region and specimen collection method. Cyathostomins infect virtually all horses, and concomitant infections with 10 or more species per horse is standard. Species-specific knowledge is limited, despite potential species bias in development of disease and anthelmintic resistance. This is the first meta-analysis to examine effects of geographical region and cyathostomin collection method on reported composition of cyathostomin communities. Methods: Thirty-seven articles published in English in 1975 or later, in which adults of individual species were systematically enumerated, were included. Seven regions; North America, South Ameri...
Importation of macrocyclic lactone resistant cyathostomins on a US thoroughbred farm. Anthelmintic resistance in equine cyathostomins is both widespread and highly prevalent in the benzimidazole and tetrahydropyrimidine classes; however, reports of resistance to macrocyclic lactone (ML) drugs are sparse and sporadic. This study reports a case of clear ML resistance in a group of Thoroughbred yearlings imported from Ireland to the US in 2019. Fecal egg count reduction (FECR) following ivermectin administered in February 2020 demonstrated 100% reduction in the US bred yearlings, but 93.5%, 70.5%, and 74.5% reduction in three groups of the imported yearlings. The two former groups...
Anthelmintic Efficacy of Strongyle Nematodes to Ivermectin and Fenbendazole on Working Donkeys (Equus asinus) in and around Hosaena Town, Southern Ethiopia. Gastrointestinal helminth parasite infection is a major influencing factor against profitability of working equines all over the world. Objective: A study was conducted from October 2016 to May 2017 in and around Hosaena to determine the efficacy of benzimidazole (BZ) and avermectin (AVM) chemical groups against strongyle nematodes in working donkeys. Methods: A total of 230 donkeys from Hosaena, Soro, Anlemo, and Gombora were randomly allocated into 5 groups of 46 donkeys in each group. All groups, except group 1 (control), were treated with ivermectin 1%, ivertong 10%, fenbendazole, and Fena...
Climate change is likely to increase the development rate of anthelmintic resistance in equine cyathostomins in New Zealand. Climate change is likely to influence livestock production by increasing the prevalence of diseases, including parasites. The traditional practice of controlling nematodes in livestock by the application of anthelmintics is, however, increasingly compromised by the development of resistance to these drugs in parasite populations. This study used a previously developed simulation model of the entire equine cyathostomin lifecycle to investigate the effect a changing climate would have on the development of anthelmintic resistance. Climate data from six General Circulation Models based on four di...
The P-glycoprotein repertoire of the equine parasitic nematode Parascaris univalens. P-glycoproteins (Pgp) have been proposed as contributors to the widespread macrocyclic lactone (ML) resistance in several nematode species including a major pathogen of foals, Parascaris univalens. Using new and available RNA-seq data, ten different genomic loci encoding Pgps were identified and characterized by transcriptome-guided RT-PCRs and Sanger sequencing. Phylogenetic analysis revealed an ascarid-specific Pgp lineage, Pgp-18, as well as two paralogues of Pgp-11 and Pgp-16. Comparative gene expression analyses in P. univalens and Caenorhabditis elegans show that the intestine is the maj...
Prevalence of gastrointestinal nematodes, parasite control practices and anthelmintic resistance patterns in a working horse population in Egypt. Anthelmintic resistance is commonly reported in horse populations in developed countries, but evidence in some working horse populations is either lacking or inconclusive. Objective: To estimate prevalence of GI nematode infections in working horses in Egypt and to evaluate strongyle resistance to ivermectin, doramectin and fenbendazole. Methods: Cross-sectional study. Methods: Faecal egg count was performed on 644 working horses from 2 provinces in Egypt. A short questionnaire about horse signalment and worming history was completed for each horse. Horses identified with ≥50 strongyle type ...
Novel Equine Faecal Egg Diagnostics: Validation of the FECPAKG2. Faecal egg counts (FECs) are the standard method of diagnosing the level of parasitic helminth egg shedding in horses and other grazing animals. Testing before treatment is an important factor in slowing the appearance of anthelmintic resistance in nematode parasites. The FECPAK, optimised for livestock, is reported to allow owners to perform FECs on their own animals without the need for a separate microscope or any specialist knowledge by tapping into remote expertise. However, the performance of the FECPAK has yet to be assessed for equids. Therefore, a comparison of the FECPAK (G2) method ...
Transcriptional responses in Parascaris univalens after in vitro exposure to ivermectin, pyrantel citrate and thiabendazole. Parascaris univalens is a pathogenic parasite of foals and yearlings worldwide. In recent years, Parascaris spp. worms have developed resistance to several of the commonly used anthelmintics, though currently the mechanisms behind this development are unknown. The aim of this study was to investigate the transcriptional responses in adult P. univalens worms after in vitro exposure to different concentrations of three anthelmintic drugs, focusing on drug targets and drug metabolising pathways. Methods: Adult worms were collected from the intestines of two foals at slaughter. The foals were natu...
Habronematidosis in Equids: Current Status, Advances, Future Challenges. Over the past few decades, among equine parasitoses caused by gastrointestinal nematodes, habronematidosis has been discontinuously studied worldwide. Habronematidosis is a parasitic disease distributed all over the world. It is caused by Habronema microstoma, Habronema muscae, and Draschia megastoma (Spirurida, Habronematidae), and it is maintained in the environment by muscid flies which act as intermediate hosts. At larval and adult stages these species live in the stomach of domestic and wild equids. However, the larvae can also be found on the skin, causing lesions known as "summer sores"...
A survey of ivermectin resistance in Parascaris species infected foals in south-eastern Poland. Parascaris spp. are major gastro-intestinal nematodes that infect foals and can lead to respiratory symptoms, poor growth, and in some cases obstruction of the small intestine and death. Ivermectin resistance has been reported for Parascaris spp. in many countries. In Poland, the knowledge of the level of resistance against ivermectin in Parascaris spp. is limited. The aim of this study was to examine the efficacy of ivermectin against Parascaris spp. in foals from south-eastern Poland. Foals (n = 225 = reared in 7 stud farms) were treated orally with ivermectin paste. Faecal samples w...
Anthelmintic resistance in strongylids (Nematoda: Strongylidae) parasitizing wild and domestic equids in the Askania Nova Biosphere Reserve, Ukraine. Resistance of strongylids in domestic horses to benzimidazole anthelmintics (BZ) has been detected worldwide; however, information on the presence of BZ-resistance in wild equids has not been published to date. The purpose of this study was to analyze the manifestations of the BZ resistance in strongylids in domestic and wild equids kept in the Askania Nova Biosphere Reserve, Ukraine. Four species of equids: domestic horses and Shetland ponies (Equus caballus), donkeys (E. asinus), plains zebras (E. burchelli) and Grévy’s zebras (E. grevyi) kept under semi-free conditions were examined usin...
