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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.
Coprological assessment of gastrointestinal helminths in Arabian Thoroughbred horses housed in a stable in the Constantine region, Algeria. This study assesses the gastrointestinal parasitological status of Arabian Thoroughbred horses at the Eastern Equestrian Club in Constantine (Algeria). In this semi-arid region, epidemiological data on equine parasitoses are lacking. Twenty fecal samples were analyzed using qualitative (flotation) and quantitative (McMaster) methods, complemented by morphological identification of parasitic eggs. The results reveal an overall prevalence of 50 %, with species diversity dominated by strongyles (60 % of positive cases), followed by (40 %), spp. (30 %), (20 %), and spp. (10 %). The excretion i...
Cyathostomin species richness and alpha diversity at egg reappearance following fecal egg count-based selective ivermectin treatment. Cyathostomin nematodes are ubiquitous in grazing horses. The overuse of anthelmintics has led to increasing problems with drug resistance to benzimidazoles and pyrantel. Although macrocyclic lactones (ML), such as ivermectin, generally retain the highest efficacy, reduced ML efficacy has increasingly been reported. A shortened egg reappearance period (ERP) is frequently used as an indicator of reduced susceptibility. However, the species-specific response dynamics after ivermectin treatment are inadequately characterized in cyathostomins. The objective of this study was to compare the cyathost...
Three-year evaluation of anthelmintic treatment efficacy against equine strongyles in France using FECRT. Reduced anthelmintic efficacy against strongyles in equids is a widespread concern, but up-to-date field data are scarce. The aim of this study was to evaluate, over a three-year period, the efficacy of the anthelmintic (AH) molecules available in France (fenbendazole, pyrantel, ivermectin and moxidectin) against strongyles in equids using faecal egg count reduction tests (FECRTs). A total of 104 complete FECRTs (i.e., required sample size reached) were conducted in 98 groups, involving 749 equids kept in 70 facilities. Fenbendazole-resistant populations were detected in 8/9 groups (89%) from ...
Simple and efficient HPLC-MS/MS method for simultaneous extraction and quantification of anthelmintics in equine manure. Anthelmintic treatment is a common practice in horses. The presence of pharmaceutical residues in fields and pastures is well-documented affecting various organisms, like nematodes. This study describes the development and validation of a high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method using multiple reaction monitoring (MRM) for extracting and determining the concentrations of four commonly used anthelmintics in horse manure. Manure was initially dried, then spiked with various concentrations (10-10,000 ng) of anthelmintics and extracted using an acetonit...
Equine cyathostomins-Hidden histories. Cyathostomins (also known as small strongyles or small redworms) are ubiquitous parasites of equids. They are found in a wide range of climatic regions, and inhabit the large intestine of their hosts. While infections are often sub-clinical, clinical consequences ranging from chronic to acute, and most notably, acute larval cyathostominosis, can occur in specific circumstances. Control of cyathostomin infection is complicated by widespread drug resistance. This Chapter provides a broad review of cyathostomin biology and host-parasite relationships, and also highlights significant knowledge gap...
Parascaris spp. induced surgical colic in juvenile horses-A Scandinavian perspective. Parascaris spp. commonly infects foals, and high burdens can cause fatal small intestinal impactions. Progressive anthelmintic resistance poses a risk for an increase of Parascaris spp. related disease in juvenile horses. Objective: To investigate Parascaris-related surgical intestinal lesions, with special emphasis on ascarid impactions, in Scandinavia by exploring (1) disease occurrence and (2) short-term survival rates after laparotomy in affected foals and yearlings. Methods: Restrospective case series. Methods: A retrospective clinical record search was conducted at six Scandinavian equin...
Current consensus and controversies in equine parasite control. Julia Shrubb, chair of CANTER - Controlling ANTiparasitic resistance in Equines Responsibly - takes a look at where there is currently agreement on equine parasite control practices and where debate is ongoing.
Terpenic compounds possess anthelmintic and immunomodulatory properties with potential for controlling equine cyathostomin infections. The emergence of anthelmintic-resistant parasite isolates necessitates alternative control strategies. The use of dietary additives with anti-parasitic or immunomodulatory activities has been proposed as a solution, but whether such additives can simultaneously exert dual bioactivities within this context has rarely been explored. Here, we evaluated whether selected terpenes could exert dual bioactivities (anti-parasitic and immunomodulatory) with a view to their use as food additives that can limit strongyle infections in horses. In vitro tests with cyathostomin larval development, larval mig...
Modified mucosal digestion procedure improves precision of encysted larval cyathostomin counts in horses. With rising anthelmintic resistance in adult cyathostomins, the most pervasive equine parasites, the need to assess larvicidal efficacy has increased, yet available methods remain limited. Encysted larvae are quantified using mucosal digestion, wherein a 5% subsample of intestinal mucosa is processed, and a 2% aliquot is counted for early third stage (EL3) and late third stage/mucosal fourth stage (LL3/L4) larvae. This method is imprecise and post-treatment larval differences are often not observed. The following study aimed to assess standard and modified protocol precision and sensitivity. I...
Epidemiological study and risk factors of equine (Equus ferus caballus) gastrointestinal helminth infections in the north and northeast of Iran. Understanding the epidemiology of gastrointestinal (GI) helminth infections in equines is critical for investigating drug resistance patterns and developing effective strategies to control and prevent these infections. There is a lack of data regarding horse GI helminths and risk factors in the north and northeast of Iran. Hence, the present study aimed to identify GI helminths in horses in these regions and determine their risk factors. A total of 340 fecal specimens from horses of north ( = 141) and northeast ( = 199) Iran were coprologically examined for GI helminth infections. The poly...
Parasite management practices used by owners of Australian Pony Club horses and the factors influencing their decision-making processes. There is a lack of information on horse parasite management practices currently used by individual horse owners in Australia. A voluntary, anonymous online survey was developed for and distributed by Pony Club Australia to its members seeking information on horse population; housing; paddock, manure and parasite management; and owner attitudes. From a total of 98 completed responses, 95/98 of participants indicated their horses spent time in paddocks, 91/98 administered anthelmintics, 42/98 guessed their horse's body weight for dosing, 78/98 recalled the dewormer brand or active ingredient las...
In vitro anthelmintic activity of extracts and bioactive compounds from Azadirachta indica and Cnidoscolus angustidens on strongyles L3 larvae in horses. Gastrointestinal endoparasitic diseases, particularly those caused by some strongyles, represent one of the main health challenges in equine production. The prolonged use of synthetic anthelmintics has led to the development of resistance, which has prompted the search for more sustainable therapeutic alternatives. However, plant extracts rich in secondary metabolites are emerging as a promising option. Objective: The objective of this study was to evaluate the in vitro anthelmintic activity of aqueous extracts and bioactive compounds (total phenols and saponins) from Azadirachta indica and Cn...
Antiparasitic potential of Caesalpinia coriaria: Current evidence and prospects for equine health. Parasitic infections remain a major constraint to equine health and performance, and the worldwide rise of anthelmintic resistance is forcing a shift toward integrated parasite management and new complementary tools. Caesalpinia coriaria (Divi-divi) pods are exceptionally rich in tannins and have been proposed as a potential source of antiparasitic phytochemicals. This review summarizes the current evidence on C. coriaria, focusing on its relevance to equine gastrointestinal helminths. Most available data come from in vitro screening against ruminant nematode models (mainly Haemonchus contortu...
Beyond the host: Unveiling the independent microbiome of equine gastrointestinal nematodes. Gastrointestinal nematode infections significantly impact equine health and welfare, with rising anthelmintic resistance demanding alternative control strategies. Emerging evidence suggests that parasitic nematodes harbour distinct microbiomes, potentially influencing host-parasite dynamics and parasite survival. This study aimed to characterize and compare the microbiomes of equine gastrointestinal nematodes and their hosts, focusing on differences in composition, diversity, and core microbiota structure across different intestinal sites, nematode subfamilies, and sexes. Faecal and nematode s...
Molecular Identification and Benzimidazole Resistance Analysis of Cyathostomins in Chinese Grazing Horses. This study investigated the cyathostomin species composition, anthelmintic efficacy, and potential resistance-associated mutations in Chinese grazing horses. Fecal samples were collected from 90 adult horses. Fecal egg counts (FECs) were determined using a modified McMaster method. Third stage larvae (L3) cultured from the eggs were identified to species level by PCR amplification and sequencing of the internal transcribed spacer-2 (ITS-2). The main species included and spp. However, differences in the relative abundance of less common species, including and , suggests regional variation. A...
Relationship Between Mean Faecal Gastrointestinal Nematode Egg Excretion in Horses and Its Variability: Implications for Control. Faecal egg counts (FECs) are used to assess the intensity of gastrointestinal nematode (GIN) infections in herbivores. FEC distribution is aggregated, meaning that approximately 20% of animals harbour 80% of infections. In times of escalating anthelmintic resistance, it may be necessary to restrict treatment to the animals with the heaviest infections. This strategy is called targeted selective treatment (TST) and is relevant to GIN, for example. The difficulty lies in identifying which animals to treat. One solution is to select potentially at-risk animals based on age (for example, treating ...
A study on the prevalence of cyathostomin and Anoplocephala perfoliata infections in Italian horses: diagnostic testing and analysis of factors affecting infection risk. Cyathostomins and Anoplocephala perfoliata infect equids worldwide and both are of concern due to their potential to cause clinical disease. Although coprological techniques are commonly used for assessing helminth egg shedding these do not provide information about an individual's total parasite burden. Antibody-based tests provide information on infection levels within individuals. Objective: This study aimed to evaluate cyathostomin and Anoplocephala perfoliata occurrence in Italian horses using coprological and serum-based antibody detection methods and to analyse risk factors for infectio...
Enhanced detection of equine strongyles: Insights from morphological and nemabiome metabarcoding approaches in northern Iran. Strongyles pose significant health concerns for equids globally. Strongyles, comprising over 60 species, can lead to severe morbidity and mortality, with Strongylus vulgaris posing higher risks due to its migratory behaviour. Routine diagnostic methods, such as faecal egg counts, lack species-level resolution, while traditional morphological techniques require advanced expertise. DNA metabarcoding offers a high-throughput alternative. Objective: To characterise the diversity of strongyles infecting horses in northern Iran and evaluate how age, sex, diagnostic methods and host population influe...
Evaluation of Benzimidazole Resistance in Equine Cyathostomins in the Kermanshah Province of Iran Using Coprological Analysis and Allele-Specific PCR. Resistance to benzimidazole (BZ) by cyathostomin nematodes has become a major threat to equine health around the world. We aimed to evaluate the efficacy of BZ drugs against small strongyle nematodes in horses of western Iran using coprological and molecular examination. Unassigned: Faecal egg count reduction tests were performed on 398 horses kept in 16 stables in western Iran (Kermanshah Province), to detect benzimidazole resistance in small strongyle nematodes. Allele-specific PCR was used to identify the F200Y (TAC/TTC) SNP in the beta-tubulin gene codon in cyathostomin larvae. Unassigned:...
Treatment efficacy of pyrantel, fenbendazole and macrocyclic lactones in equine strongyles in Germany using FECRT and the model eggCounts. Reduced anthelmintic efficacy against small strongyles in horses is a widespread problem, yet recent data is scarce. Objective: This paper aims to investigate the current status of anthelmintic efficacy in the field in Germany, specifically focusing on pyrantel. Methods: The study included 1670 horses for which a total of 1913 dewormings were analysed. Of these, 1682 were performed with pyrantel, 56 with fenbendazole, 162 with macrocyclic lactones and 13 with other compounds (e.g. herbs). The faecal egg count reduction (FECR) was calculated with two methods, the faecal egg count reduction test...
A review of current and potential applications of macroalgae to equine veterinary science. Macroalgae have been used in supplements and feedstuffs for equines and other animals for many years. Health-related attributes of macroalgal bioactive compounds, including antioxidant, anti-inflammatory and anthelmintic effects, have been largely reported in non-equine species to date. Given the prevalence of resistance to antimicrobial and anthelmintic drugs, sourcing naturally occurring alternatives is of high priority in the current One Health strategy. Nutritionally, seaweed contains a broad range of macro and micro nutrients. These nutrients, combined with the bioactive compounds such as...
Recent advances in intestinal helminth parasites of horses in the Asia-Pacific region: Current trends, challenges and future directions. Over the past 25 years, significant progress has been made in understanding and managing equine gastrointestinal parasites in the Asia-Pacific region, particularly in Australia and New Zealand. This review synthesises current knowledge of the epidemiology, diagnostic methods, anthelmintic resistance (AR), and control strategies for major equine intestinal parasites, including cyathostomins, Parascaris spp., Anoplocephala perfoliata, and Strongyloides westeri. Recent studies highlight substantial regional variation in parasite prevalence, egg shedding and cyathostomin population composition, sh...
Cytochrome c oxidase I deep amplicon sequencing for metabarcoding of equine strongyle communities: unexpectedly high Strongylus spp. prevalence in treated horses. Equines are parasitized by complex communities of Strongylidae (Nematoda) comprising multi-species infections. Currently, Cyathostominae are most prevalent, while Strongylus species are only rarely detected. Since eggs and, in most cases, infective larvae cannot be differentiated to species level, except for Strongylus spp., species-specific knowledge of the pathology, epidemiology and ecology of these parasitic nematodes is limited. Reference sequence data for several cyathostomin species are limited or missing. Deep amplicon sequencing of internal transcribed spacer 2 (ITS-2) regions of nema...
A pilot study on the potency of injectable vs. oral moxidectin formulation to suppress strongyle egg excretion in horses at twice lower dose. The aim of present study was to examine the potency of moxidectin solution (Cydectin 1 %; Zoetis) and commercially available oral moxidectin gel (Equest®; Zoetis) to suppress the excretion of strongyle eggs in horses over a 6-week period. The horses naturally infected with strongyle nematodes (>500 eggs/g of feces) were divided into two comparable groups according age, sex and weight. On day 0 of the study, horses in Group OT (oral treatment; N=5) were dewormed with moxidectin gel (Equest®; Zoetis; 0.4 mg/kg of b.w.) according to the manufacturer's instructions, and horses in Group IT (in...
Assessment of the antiparasitic effectiveness of pyrantel pamoate in treatment of Strongylidae invasions in young horses – preliminary studies. The resistance of strongyles to pyrantel pamoate has been reported in publications worldwide. There is no data on its efficacy in horses in Poland. Therefore, the aim of this study was to evaluate the effectiveness of pyrantel pamoate to control strongyle invasions in young horses. The study involved horses of both sexes, aged 1 to 2 years, and was conducted in two seasons (spring and the end of summer). Feces were collected 24 hours before and 14 days after deworming, and they were then examined using McMaster's and combined sedimentation-flotation methods. Results revealed that in spring, th...
Helminth control practices used by equine keepers in France: a national survey. In light of the increasing reports of anthelmintic (AH) resistance in equids, a national survey on helminth control practices was distributed to 42 528 keepers. A total of 4 344 responses was obtained. Respondents implemented preventive pasture practices with varying frequency according to the age of the animals, such as pasture rotations (78.1-80.6 %), excrement removal from pastures several times a year (15.9-27.2 %) and/or mixed or rotational grazing with ruminants (14.5-18.1 %). A majority of keepers routinely used AH treatments even though they did not perceive any major risk to the...
Independent Development of Resistance to Main Classes of Anthelmintics by Gastrointestinal Nematodes of Ruminants and Horses. Resistance to anthelmintics in gastrointestinal nematodes (GINs) is highly prevalent, as these parasites have been treated with anthelmintics for decades in ruminants and horses. Anthelmintics belong to different classes, each with a different mode of action. The most used are benzimidazoles and macrocyclic lactones and, to a lesser extent, levamisole and pyrantel in herbivores, as estimated from the literature. Combining these classes should be effective in controlling GIN. However, several farmers' practices tend to promote GIN resistance. Therefore, it is unclear whether the use of anthelmi...
Progress in serology and molecular biology of equine parasite diagnosis: sustainable control strategies. Internal parasitic infections are a persistent challenge for horse owners, in the absence of effective vaccines and the growing challenge of drug resistance, leading many researchers to view current control strategies as unsustainable. Despite slow progress over the past two decades, effective parasitic diagnosis remains crucial for controlling infections and preventing the growing issue of drug resistance. This review examines the research progress in serological and molecular biological diagnostic methods for major equine parasites. Currently, most diagnostic techniques are based on genes su...
In vitro and in vivo effects of Acacia mearnsii De Wild extract for cyathostomin control in horses. Anthelmintic resistance has led to the use of organic extracts as alternative methods of parasite control. Objective: The study aimed to assess the effects of Acacia mearnsii extract (tannin) on the control of cyathostomins in horses, both in vitro and in vivo. Methods: Thirty Pantaneiro horses naturally infected with cyathostomins were sourced from two distinct farms, designated as Farms A and B. At the start of the study, all third-stage larvae were cyathostomins, and an egg hatchability test (EHT) was performed using fecal samples from horses on both farms. Two randomized 28-day field studi...
Evaluating efficacy and strongyle egg reappearance period after ivermectin treatment in a Hungarian stud farm. Horses remain globally at constant risk of strongylid infections, with cyathostomins being particularly prevalent and abundant. It is essential to routinely monitor the efficacy of anthelmintics against equine nematodes. This study aimed to evaluate the efficacy of ivermectin against equine strongyles and estimate the strongyle egg reappearance period (ERP) following ivermectin treatment for the first time in Hungary. Fecal samples were collected from 57 Thoroughbred mares before treatment and at 2, 4, 5, 6, and 7 weeks post-treatment at a Hungarian National Stud Farm. Fecal egg counts (FECs)...
