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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.
Validation of a serum ELISA test for cyathostomin infection in equines.
International journal for parasitology    August 1, 2023   doi: 10.1016/j.ijpara.2023.07.001
Lightbody KL, Austin A, Lambert PA, von Samson-Himmelstjerna G, Jürgenschellert L, Krücken J, Nielsen MK, Sallé G, Reigner F, Donnelly CG....Cyathostomins are ubiquitous equine nematodes. Infection can result in larval cyathostominosis due to mass larval emergence. Although faecal egg count (FEC) tests provide estimates of egg shedding, these correlate poorly with burden and provide no information on mucosal/luminal larvae. Previous studies describe a serum IgG(T)-based ELISA (CT3) that exhibits utility for detection of mucosal/luminal cyathostomins. Here, this ELISA is optimised/validated for commercial application using sera from horses for which burden data were available. Optimisation included addition of total IgG-based calibr...
Evidence of resistance to ivermectin in the gastrointestinal nematodes of horses from Mexican southeast.
Veterinary parasitology, regional studies and reports    July 19, 2023   Volume 44 100907 doi: 10.1016/j.vprsr.2023.100907
Flota-Burgos GJ, Rosado-Aguilar JA, Rojas-Becerril R, Rodríguez-Vivas RI, Trinidad-Martínez I.Gastrointestinal nematodes (GIN) are a major impediment to breeding and exploitation of horses. Traditional control of GIN has generated resistance to main anthelmintics, including ivermectin. An analysis of five ranches with a history of IVM use was done to determine the efficacy and resistance of GIN to IVM treatment in horses from the Mexican southeast. Predesigned questionnaires were applied to collect information on previous treatment protocols. The fecal egg count reduction test (FECRT) was applied to determine resistance. Before IVM application, a McMaster test was used to diagnose GIN ...
Incidence, risk factors, and therapeutic management of equine colic in Lamongan, Indonesia.
Veterinary world    July 9, 2023   Volume 16, Issue 7 1408-1414 doi: 10.14202/vetworld.2023.1408-1414
Fikri F, Hendrawan D, Wicaksono AP, Purnomo A, Khairani S, Chhetri S, Maslamama ST, Purnama MTE.Colic is among the common health issues in equine health management. Gastrointestinal (GI) disorders are the most frequent causes of colic, but dysfunction of other organs and systems inside the abdominal cavity may also contribute. Therefore, it is crucial to identify risk factors for colic of specific etiologies. This study aimed to examine the incidence, risk factors, and best therapeutic management practices for horses with colic. Unassigned: A cohort of 256 horses living in Lamongan, East Java, Indonesia, was randomly recruited based on reports of colic symptoms by owners. Diagnosis and t...
Apparent treatment failure of praziquantel and pyrantel pamoate against anoplocephalid tapeworms.
International journal for parasitology. Drugs and drug resistance    June 19, 2023   Volume 22 96-101 doi: 10.1016/j.ijpddr.2023.06.002
Nielsen MK.Anoplocephalid tapeworms are commonly occurring in grazing horses around the world. Two currently available anthelmintics have documented high efficacy against Anoplocephala perfoliata; praziquantel in various dosages ranging from 1.0 to 2.5 mg/kg and pyrantel pamoate administered at 13.2 mg base/kg. Anthelmintic resistance has not been reported in A. perfoliata, but anecdotal reports made during 2022 have suggested a possible loss of efficacy for both actives. This paper reports fecal egg count data from a Thoroughbred operation in Central Kentucky in 2023. Fifty-six yearlings were first de...
Shortened strongylid egg reappearance periods in horses following macrocyclic lactone administration – The impact on parasite dynamics.
Veterinary parasitology    June 19, 2023   Volume 320 109977 doi: 10.1016/j.vetpar.2023.109977
Nielsen MK, Leathwick DM, Sauermann CW.Over the past three decades, equine strongylid egg reappearance periods (ERPs) have shortened substantially for macrocyclic lactone anthelmintics. The ERPs of ivermectin and moxidectin were originally reported in the 8-10 and 12-16 week ranges, respectively, but several recent studies have found them to be around 4-5 weeks for both actives. This loss of several weeks of suppressed strongylid egg output could have substantial implications for parasite control. This study made use of a computer simulation model to evaluate the impact of shortened ERPs on the anthelmintic performance of ivermecti...
Synthesis and Clinical Examination of Novel Formulations of Ivermectin, Albendazole and Niclosamide for the Treatment of Equine Gastrointestinal Helminthoses.
Iranian journal of parasitology    May 18, 2023   Volume 18, Issue 1 66-75 doi: 10.18502/ijpa.v18i1.12381
Marchenko VA, Khalikov SS, Biryukov IV, Efremova EA, Ilyin MM, Sazmand A.This study aimed to develop new complex preparations of ivermectin, niclosamide and albendazole based on solid-phase mechanochemical technology, and to evaluate their efficacy against equine nematodosis and cestodosis. Unassigned: Novel formulation of antiparasitic paste were prepared using joint mechano-chemical treatment of ivermectin (0.2 mg/kg bodyweight; BW), niclosamide (10 mg/kg BW) and albendazole (3, 5, 10 mg/kg BW) substances with polyvinylpyrrolidone and arabinogalactan. For the evaluation of activity of different doses of formulations against gastrointestinal tract helminths a tota...
World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) guideline for diagnosing anthelmintic resistance using the faecal egg count reduction test in ruminants, horses and swine.
Veterinary parasitology    April 23, 2023   Volume 318 109936 doi: 10.1016/j.vetpar.2023.109936
Kaplan RM, Denwood MJ, Nielsen MK, Thamsborg SM, Torgerson PR, Gilleard JS, Dobson RJ, Vercruysse J, Levecke B.The faecal egg count reduction test (FECRT) remains the method of choice for establishing the efficacy of anthelmintic compounds in the field, including the diagnosis of anthelmintic resistance. We present a guideline for improving the standardization and performance of the FECRT that has four sections. In the first section, we address the major issues relevant to experimental design, choice of faecal egg count (FEC) method, statistical analysis, and interpretation of the FECRT results. In the second section, we make a series of general recommendations that are applicable across all animals ad...
Awareness and control measures for gastrointestinal parasites in donkeys in Maseru district, Lesotho.
Research in veterinary science    April 5, 2023   Volume 159 19-25 doi: 10.1016/j.rvsc.2023.03.028
Nts'aoana ME, Molapo S, Kompi P, Phalatsi M.Parasitic infection is one of the major problems in equines which negatively influence their health. It hinders working performance of equines. This study was conducted to evaluate donkey owners' knowledge and control measures on prevalence of gastrointestinal parasites (GIPs) in three agro-ecological zones (AEZs) of Maseru district. A total of 144 donkey owners were selected for individual interviews through a stratified random sampling. Descriptive statistics and chi-square tests were used to analyze data. The significance (p  0.05) across the AEZs. The adult donkeys were mostly susceptibl...
Anthelmintic resistance of horse strongyle nematodes to ivermectin in São Paulo state, Brazil.
Veterinary parasitology, regional studies and reports    March 30, 2023   Volume 41 100864 doi: 10.1016/j.vprsr.2023.100864
de Favare GM, de Almeida Cipriano I, do Carmo TA, Mena MO, Guelpa GJ, do Amarante AFT, de Soutello RVG.The indiscriminate use of drugs to control gastrointestinal helminths in horses can lead to serious consequences for the animals, which represents a growing problem for health, animal welfare and productivity. Therefore, the present study aimed to evaluate the anthelmintic efficacy of ivermectin in naturally infected horses in the western region of the state of São Paulo. From May 2021 to April 2022, 123 naturally infected adult horses in 12 equine breeding farms (7 to 14 animals per farm) were evaluated with the fecal egg count reduction test. The horses had not been treated with anthelminti...
A qualitative study of perceived barriers and facilitators to sustainable parasite control on thoroughbred studs in Ireland.
Veterinary parasitology    March 5, 2023   Volume 317 109904 doi: 10.1016/j.vetpar.2023.109904
Walshe N, Burrell A, Kenny U, Mulcahy G, Duggan V, Regan A.In view of the rising threat of anthelmintic resistance in parasite populations and the planned change of classification of anthelmintics in Ireland for food animals to prescription-only medicines, there is a need for increased focus on parasite control strategies for horses. Effective parasite control programs (PCPs) are complex, necessitating the application of risk-assessment based on host immune status, infection pressure, type of parasite and seasonality to determine the requirement for anthelmintic administration and an understanding of parasite biology to employ effective, non- therapeu...
Estimating the Prevalence and Factors Affecting the Shedding of Helminth Eggs in Irish Equine Populations.
Animals : an open access journal from MDPI    February 7, 2023   Volume 13, Issue 4 doi: 10.3390/ani13040581
Elghryani N, McOwan T, Mincher C, Duggan V, de Waal T.Gastrointestinal helminths are ubiquitous in horse populations across the world. Intensive anthelmintic treatments have succeeded in controlling some of the pathogenic effects of these parasites. However, the success of anthelmintic drugs has been threatened by the development of widespread resistance to those most commonly used. To develop improved control strategies, information on helminth distribution patterns is needed, which can be obtained by identifying animals regarded as high egg shedders and taking age, gender, and other risk factors into account. The aim of this study was to determ...
Species interactions, stability, and resilience of the gut microbiota – Helminth assemblage in horses.
iScience    January 25, 2023   Volume 26, Issue 2 106044 doi: 10.1016/j.isci.2023.106044
Boisseau M, Dhorne-Pollet S, Bars-Cortina D, Courtot É, Serreau D, Annonay G, Lluch J, Gesbert A, Reigner F, Sallé G, Mach N.The nature and strength of interactions entertained among helminths and their host gut microbiota remain largely unexplored. Using 40 naturally infected Welsh ponies, we tracked the gut microbiota-cyathostomin temporal dynamics and stability before and following anthelmintic treatment and the associated host blood transcriptomic response. High shedders harbored 14 species of cyathostomins, dominated by . They exhibited a highly diverse and temporal dynamic gut microbiota, with butyrate-producing Clostridia likely driving the ecosystem steadiness and host tolerance toward cyathostomins infectio...
Epidemiological study on factors influencing the occurrence of helminth eggs in horses in Germany based on sent-in diagnostic samples.
Parasitology research    January 11, 2023   Volume 122, Issue 3 749-767 doi: 10.1007/s00436-022-07765-4
Boelow H, Krücken J, von Samson-Himmelstjerna G.Gastrointestinal nematodes are ubiquitous parasites of grazing equines with Parascaris spp., and strongyles being the most relevant ones regarding the prevalence and potential disease severity. Despite their importance, epidemiological data regarding the presence and egg-shedding intensities of these parasites are scarce. Data from 1067 horse samples collected on German horse farms initially to compare diagnostic methods were used for epidemiological analyses. Due to its higher sensitivity, presence/absence data were based on a combined sedimentation/flotation technique while faecal egg counts...
Egg reappearance periods of anthelmintics against equine cyathostomins: The state of play revisited.
International journal for parasitology. Drugs and drug resistance    December 13, 2022   Volume 21 28-39 doi: 10.1016/j.ijpddr.2022.12.002
Macdonald SL, Abbas G, Ghafar A, Gauci CG, Bauquier J, El-Hage C, Tennent-Brown B, Wilkes EJA, Beasley A, Jacobson C, Cudmore L, Carrigan P, Hurley J....Cyathostomins are the most common and highly prevalent parasites of horses worldwide. Historically, the control of cyathostomins has mainly relied on the routine use of anthelmintic products. Increasing reports on anthelmintic resistance (AR) in cyathostomins are concerning. A potential method proposed for detecting emerging AR in cyathostomins has been estimating the egg reappearance period (ERP). This paper reviews the data available for the ERP of cyathostomins against the three major classes of anthelmintics, macrocyclic lactones, tetrahydropyrimidines, and benzimidazoles. Published peer-r...
Disseminated Halicephalobus gingivalis infection in a horse. Pillai VV, Mudd LJ, Sola MF.A 19-y-old American Saddlebred gelding was evaluated for epiphora of the right eye and generalized cachexia. Initial examination revealed anterior uveitis without ulceration, for which treatment was initiated. Despite the initial response to treatment, the signs progressively worsened to blindness. Histologic examination of the enucleated eye revealed granulomatous panuveitis and optic neuritis with intralesional nematode larvae identified as . Over time and despite anthelmintic treatment, blindness developed in the left eye along with neurologic signs, and the horse was euthanized. Disseminat...
Anthelmintic efficacy in strongyles of horses in Northern Minas Gerais, Brazil.
Veterinary parasitology, regional studies and reports    November 24, 2022   Volume 36 100810 doi: 10.1016/j.vprsr.2022.100810
Apolinário ECF, Oliveira LLDS, Rocha RHF, Silva FVE, Santos IS, Alves CA, Dias Júnior JA, Mendes LJ, Lima WDS.The intensive use of anthelmintics has resulted in resistant parasite populations in horses. The objective of this trial was to evaluate the anthelmintic efficacies of the anthelmintics fenbendazole, ivermectin and abamectin in 24 horse farms in Northern Minas Gerais. Egg counts per gram of faeces (EPG) were performed individually in 619 animals. Animals presenting EPG counts greater than or equal to 150 were used in the tests on faecal egg count reduction (FECR), totalling 436 equines. These animals received the anthelmintics, fenbendazole, ivermectin, and abamectin. Faeces were collected 14...
Shortened egg reappearance periods of equine cyathostomins following ivermectin or moxidectin treatment: morphological and molecular investigation of efficacy and species composition.
International journal for parasitology    October 13, 2022   Volume 52, Issue 12 787-798 doi: 10.1016/j.ijpara.2022.09.003
Nielsen MK, Steuer AE, Anderson HP, Gavriliuc S, Carpenter AB, Redman EM, Gilleard JS, Reinemeyer CR, Poissant J.Macrocyclic lactones have been the most widely used drugs for equine parasite control during the past four decades. Unlike ivermectin, moxidectin exhibits efficacy against encysted cyathostomin larvae, and is reported to have persistent efficacy with substantially longer egg reappearance periods. However, shortened egg reappearance periods have been reported recently for both macrocyclic lactones, and these findings have raised several questions: (i) are egg reappearance period patterns different after ivermectin or moxidectin treatment? (ii) Are shortened egg reappearance periods associated w...
Anthelmintic resistance of horse strongyle nematodes to fenbendazole in Lithuania.
Acta veterinaria Scandinavica    September 15, 2022   Volume 64, Issue 1 26 doi: 10.1186/s13028-022-00645-y
Dauparaitė E, Kupčinskas T, Varady M, Petkevičius S.Control of strongyle infections presents a global challenge for horse practitioners due to the development of anthelmintic resistance (AR), however comprehensive information on AR in Lithuania is still lacking. The aim of this study was to assess the current situation of fenbendazole (FBZ) AR in horses at stable level in Lithuania. Results: Faecal samples from 121 horses from six stables were examined using the Mini-FLOTAC method. Of these, 89 horses met the inclusion criteria that included strongyle faecal egg counts (FEC) exceeding 200 eggs per gram (EPG). Faecal egg count reduction tests (F...
Efficient and Scalable Process to Produce Novel and Highly Bioactive Purified Cytosolic Crystals from Bacillus thuringiensis.
Microbiology spectrum    August 10, 2022   Volume 10, Issue 4 e0235622 doi: 10.1128/spectrum.02356-22
Chicca J, Cazeault NR, Rus F, Abraham A, Garceau C, Li H, Atwa SM, Flanagan K, Soto ER, Morrison MS, Gazzola D, Hu Y, Liu DR, Nielsen MK, Urban JF....Bacillus thuringiensis (Bt) is a Gram-positive soil bacterium that is widely and safely applied in the environment as an insecticide for combatting insect pests that damage crops or are disease vectors. Dominant active ingredients made by Bt are insect-killing crystal (Cry) proteins released as crystalline inclusions upon bacterial sporulation. Some Bt Cry proteins, e.g., Cry5B (formally Cry5Ba1), target nematodes (roundworms) and show exceptional promise as anthelmintics (cures for parasitic nematode diseases). We have recently described inactivated bacteria with cytosolic crystal(s) (IBaCC) ...
Comparison of the host response to larvicidal and nonlarvicidal treatment of naturally acquired cyathostomin infections in horses.
Parasite immunology    August 2, 2022   Volume 44, Issue 10 e12941 doi: 10.1111/pim.12941
Steuer AE, Scoggin K, Stewart JC, Barker VD, Adams AA, Loynachan AT, Nielsen MK.This study aimed to collect information on local and systemic inflammatory responses, and goblet cell-associated components, following anthelmintic treatment with moxidectin and ivermectin in horses naturally infected with cyathostomin parasites. Thirty-six horses aged 2-5 years of age were randomly allocated to three groups. Group 1 received ivermectin/praziquantel (0.2 mg/kg), Group 2 received moxidectin/praziquantel (0.4 mg/kg) and Group 3 were untreated controls. Tissue samples from the Cecum, Dorsal and Ventral Colons were used for histopathological evaluation and preserved for RNA is...
Reduction of the nematode egg reappearance period in horses after anthelmintic therapy.
Veterinary world    June 24, 2022   Volume 15, Issue 6 1530-1534 doi: 10.14202/vetworld.2022.1530-1534
Baranova MV, Panova OA, Polukhina DN, Panova DS.Anthelmintics are used to control equine nematodes. However, helminth resistance to regularly used drugs is a well-known challenge. Among tests to assess effective control and monitor resistance, the most common is the fecal egg count reduction test (FECRT). In the absence of reliable FECRT results, the nematode egg reappearance period (ERP) is taken into account. This study aimed to examine horses from farms around the Moscow Region to assess nematode resistance through ERP after therapy. Unassigned: In the first stage, fecal samples from 280 horses were examined by the flotation method with ...
Occurrence of Strongylid Nematode Parasites on Horse Farms in Berlin and Brandenburg, Germany, With High Seroprevalence of Strongylus vulgaris Infection.
Frontiers in veterinary science    June 10, 2022   Volume 9 892920 doi: 10.3389/fvets.2022.892920
Jürgenschellert L, Krücken J, Bousquet E, Bartz J, Heyer N, Nielsen MK, von Samson-Himmelstjerna G.The infection of horses with strongylid nematodes is highly prevalent, with multi-species infections being the rule. spp. and in particular are amongst the most pathogenic strongyle equine parasites. Presumably due to regular strategic anthelmintic treatments in combination with long prepatencies, prevalence of these worms was severely reduced in past decades. In this study, 484 horses from 48 farms in Berlin/Brandenburg, Germany were sampled between May 2017 and January 2018. Mini-FLOTAC and combined sedimentation/flotation were used to analyse faecal samples and larval cultures were carrie...
Reflections and future directions for continued development and refinement of guidelines for anthelmintic efficacy studies.
Veterinary parasitology    June 1, 2022   Volume 307-308 109741 doi: 10.1016/j.vetpar.2022.109741
Geurden T, Smith ER, Vercruysse J, Yazwinski T, Rehbein S, Nielsen MK.This reflection paper complements the WAAVP (World Association for the Advancement of Veterinary Parasitology) general anthelmintic efficacy guideline, which outlines the general principles of anthelmintic efficacy evaluation across all animal host species. It provides background to the recommendations made in the WAAVP general anthelmintic efficacy guideline, with insights into the discussions leading to specific recommendations in the general guideline or the absence thereof. Furthermore, this paper discusses recent technological advancements with potential value to the evaluation of anthelm...
Comparison of FECPAKG2, a modified Mini-FLOTAC technique and combined sedimentation and flotation for the coproscopic examination of helminth eggs in horses.
Parasites & vectors    May 12, 2022   Volume 15, Issue 1 166 doi: 10.1186/s13071-022-05266-y
Boelow H, Krücken J, Thomas E, Mirams G, von Samson-Himmelstjerna G.Due to high prevalence of anthelmintic resistance in equine helminths, selective treatment is increasingly promoted and in some countries a positive infection diagnosis is mandatory before treatment. Selective treatment is typically recommended when the number of worm eggs per gram faeces (epg) exceeds a particular threshold. In the present study we compared the semi-quantitative sedimentation/flotation method with the quantitative methods Mini-FLOTAC and FECPAK in terms of precision, sensitivity, inter-rater reliability and correlation of worm egg counts to improve the choice of optimal diagn...
Monitoring anthelmintic use in horses.
The Veterinary record    May 7, 2022   Volume 190, Issue 9 373 doi: 10.1002/vetr.1767
Mair T, Shrubb J, Rendle D, Scott C, Hunter G, Parker R, Robinson N, Dean R.No abstract available
Helminths and their management in Swiss Army horses: differences between riding horses and pack horses evidence the need of improvement.
Schweizer Archiv fur Tierheilkunde    May 5, 2022   Volume 164, Issue 5 385-399 doi: 10.17236/sat00355
Spieler N, Schnyder M.Intestinal helminth management in horses has both clinical and epidemiologic relevance, in additional association with anthelmintic resistance. The Swiss Army employs military owned riding horses and privately owned pack horses, which are brought together for service periods up to 12 weeks. We compared husbandry conditions and intestinal helminth management of both groups via questionnaire and analysed faecal samples of 53 riding horses and 130 pack horses using combined sedimentation/flotation, the McMaster method and larval cultures. Riding horses only had cyathostomin infections (prevalence...
Farmers’ perception on the control of gastrointestinal parasites in organic and conventional sheep production in Sweden.
Veterinary parasitology, regional studies and reports    February 24, 2022   Volume 30 100713 doi: 10.1016/j.vprsr.2022.100713
Halvarsson P, Gustafsson K, Höglund J.A questionnaire was sent to sheep owners in Sweden to get information about anthelmintic drug use. The survey also investigated how respondents experienced problems with gastrointestinal nematode infections (GIN) focusing on Haemonchus contortus. The response rate was 31% and included both conventional and organic farms. The use of anthelmintics was low (45%), among which a majority (76%) drenched ewes on a single occasion, mostly with ivermectin (59%) followed by albendazole (19%). Other drugs were used rarely, however, unawareness of GIN risk was high (19%), especially among respondents with...
Total Failure of Fenbendazole to Control Strongylid Infections in Czech Horse Operations.
Frontiers in veterinary science    February 21, 2022   Volume 9 833204 doi: 10.3389/fvets.2022.833204
Nápravníková J, Várady M, Vadlejch J.The control of strongylid infections has become challenging globally for equine practitioners due to the development of anthelmintic resistance. Comprehensive information on anthelmintic resistance in the Czech Republic, however, is still lacking. This study monitored the current efficacy of fenbendazole, pyrantel embonate, ivermectin and moxidectin. Forty-eight of 71 operations met the criteria (≥6 horses with ≥200 eggs per gram), with 969 fecal egg count reduction tests performed. Anthelmintic resistance was evaluated on an operation level based on fecal egg count reduction (FECR) and th...
World association for the advancement of veterinary parasitology (WAAVP): Third edition of guideline for evaluating the efficacy of equine anthelmintics.
Veterinary parasitology    February 8, 2022   Volume 303 109676 doi: 10.1016/j.vetpar.2022.109676
Nielsen MK, von Samson-Himmelstjerna G, Kuzmina TA, van Doorn DCK, Meana A, Rehbein S, Elliott T, Reinemeyer CR.This guideline have been developed to assist in the design, execution, and interpretation of studies to assess the efficacy of anthelmintic drugs against internal parasites of equines, including nematodes, cestodes, and larval instars of Gasterophilus spp. The design and execution of critical and controlled studies are outlined, and their advantages and disadvantages are discussed. Unique considerations for specific target parasites are included. Information is also provided on selection of animals, procedures for randomization, housing, feeding, dosage titration, dosage confirmation and field...
Cyathostomin resistance to moxidectin and combinations of anthelmintics in Australian horses.
Parasites & vectors    December 4, 2021   Volume 14, Issue 1 597 doi: 10.1186/s13071-021-05103-8
Abbas G, Ghafar A, Hurley J, Bauquier J, Beasley A, Wilkes EJA, Jacobson C, El-Hage C, Cudmore L, Carrigan P, Tennent-Brown B, Gauci CG, Nielsen MK....Cyathostomins are the most important and common parasitic nematodes of horses, with > 50 species known to occur worldwide. The frequent and indiscriminate use of anthelmintics has resulted in the development of anthelmintic resistance (AR) in horse nematodes. In this study we assessed the efficacy of commonly used anthelmintics against cyathostomins in Australian thoroughbred horses. Methods: Two drug efficacy trials per farm were conducted on two thoroughbred horse farms in the state of Victoria, Australia. In the first trial, the horses on Farm A were treated with single and combinations ...