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D E Granstrom - One of the best experts on this subject based on the ideXlab platform.
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A study (1977–1992) of population dynamics of endoparasites featuring benzimidazole-resistant small strongyles (Population S) in Shetland ponies
Veterinary Parasitology, 1996Co-Authors: Eugene T. Lyons, Sharon C. Tolliver, Drudge Jh, S Stamper, Thomas W. Swerczek, D E GranstromAbstract:Abstract Critical tests (91) were done between 1977 and 1992 in Shetland ponies to evaluate drug susceptibility and population dynamics (present paper) of endoparasites. The test ponies, most less than 1 year old, were from a herd where older animals were treated every 8 weeks initially with cambendazole (CBZ) (1974–1978) and then with Oxibendazole (OBZ) (1978–1992). Previous field test data (1974–1992) on older ponies in the breeding herd indicated the presence of benzimidazole (BZ) resistant small strongyles. Data on population dynamics from the present critical tests indicated that 28 species of small strongyles persisted over the study period in spite of initial susceptibility and later refractiveness of six species to both CBZ and OBZ. Changes in intensities and other aspects were observed for the six BZ-resistant species ( Cyathostomum catinatum, Cyathostomum coronatum, Cylicocyclus nassatus, Cylicostephanus calicatus, Cylicostephanus goldi , and Cylicostephanus longibursatus ). Variabilities, some striking, were found in prevalence and intensity in bots, stomach worms, ascarids, eyeworms, large strongyles, pinworms and tapeworms.
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control of cambendazole resistant small strongyles population s with Oxibendazole in a pony band an 8 year field test 1984 1992
Veterinary Parasitology, 1994Co-Authors: E T Lyons, J H Drudge, S C Tolliver, S Stamper, T W Swerczek, D E GranstromAbstract:Abstract Studies in a band of ponies harboring Population S benzimidazole-resistant small strongyles were initiated in 1974 and have continued for 18 years. Treatment (bimonthly) was with cambendazole for the first 4 years and with Oxibendazole (OBZ) for the next 14 years. Data on the first 10 years have been published. The present investigation includes the last 8 years (4 October 1984-11 September 1992), which are the seventh through fourteenth years, of treatment with OBZ. Pre- and posttreatment mean counts of strongyle eggs (epg) and larvae (lpg) per gram of feces were determined biweekly during the current study to monitor the efficacy of OBZ. The average annual percent reductions of epg counts effected by OBZ treatments were 51%, 53%, 38%, 38%, 39%, 28%, 40%, and 19% for the seventhth through fourteenth years, respectively. Similar levels of reductions were observed for lpg counts. Although OBZ was initially highly effective on this population of small strongyles, epg and lpg counts gradually declined, but have remained more or less constant since the fifth year of research. However, reductions of the counts were the lowest for the last year of the study.
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Control of cambendazole-resistant small strongyles (Population S) with Oxibendazole in a pony band: an 8 year field test (1984–1992)
Veterinary Parasitology, 1994Co-Authors: Eugene T. Lyons, Sharon C. Tolliver, Drudge Jh, S Stamper, Thomas W. Swerczek, D E GranstromAbstract:Abstract Studies in a band of ponies harboring Population S benzimidazole-resistant small strongyles were initiated in 1974 and have continued for 18 years. Treatment (bimonthly) was with cambendazole for the first 4 years and with Oxibendazole (OBZ) for the next 14 years. Data on the first 10 years have been published. The present investigation includes the last 8 years (4 October 1984-11 September 1992), which are the seventh through fourteenth years, of treatment with OBZ. Pre- and posttreatment mean counts of strongyle eggs (epg) and larvae (lpg) per gram of feces were determined biweekly during the current study to monitor the efficacy of OBZ. The average annual percent reductions of epg counts effected by OBZ treatments were 51%, 53%, 38%, 38%, 39%, 28%, 40%, and 19% for the seventhth through fourteenth years, respectively. Similar levels of reductions were observed for lpg counts. Although OBZ was initially highly effective on this population of small strongyles, epg and lpg counts gradually declined, but have remained more or less constant since the fifth year of research. However, reductions of the counts were the lowest for the last year of the study.
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critical tests of thiabendazole Oxibendazole and oxfendazole for drug resistance of population b equine small strongyles 1989 and 1990
American Journal of Veterinary Research, 1993Co-Authors: S C Tolliver, J H Drudge, E T Lyons, S Stamper, D E GranstromAbstract:: Critical tests were conducted in horses (n = 11) with naturally acquired infections of benzimidazole (BZ)-resistant population-B small strongyles in 1989 and 1990. Anthelmintics administered were thiabendazole (44 mg/kg of body weight, n = 4), Oxibendazole (10 mg/kg, n = 3), and oxfendazole (OFZ, 10 mg/kg; n = 4). All compounds were paste formulations administered orally except for 1 of the OFZ treatments, which was a suspension formulation given by stomach tube. Aggregate mean efficacy was calculated for all species of small strongyles, drug-resistant and non-resistant. The highest efficacy was for Oxibendazole (98%) and OFZ (94%); efficacy for thiabendazole was 63%. Five genera and 16 species of small strongyles were recovered from the 11 horses, ranging from 7 to 13 species (mean, 11). Of these, 7 species were found to have resistance in variable degrees to most of the anthelmintics. These strongyles were Cyathostomum catinatum, Cyathostomum coronatum, Cylicocyclus nassatus, Cylicostephanus calicatus, Cylicostephanus goldi, Cylicostephanus longibursatus, and Cylicostephanus minutus. The large strongyle, Strongylus vulgaris, was present in all 11 test horses, and efficacy was 100% for all drugs. Seven of the BZ-treated foals (at least 1 horse from each BZ-treatment group), were infected with S edentatus; removal was 100%.
Eugene T. Lyons - One of the best experts on this subject based on the ideXlab platform.
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Dealing with double trouble: Combination deworming against double-drug resistant cyathostomins.
International Journal for Parasitology-Drugs and Drug Resistance, 2019Co-Authors: J.a. Scare, Eugene T. Lyons, Dave M. Leathwick, Christian W. Sauermann, A.e. Steuer, B.a. Jones, M. Clark, Martin K. NielsenAbstract:Abstract An alternative control regimen for drug-resistant parasites is combination deworming, where two drugs with different modes of action are administered simultaneously to target the same parasite. Few studies have investigated this in equine cyathostomins. We previously reported that an Oxibendazole (OBZ) and pyrantel pamoate (PYR) combination was not sustainable against a cyathostomin population with high levels of OBZ and PYR resistance. This study consisted of a field study and two computer simulations to evaluate the efficacy of a moxidectin-Oxibendazole (MOX-OBZ) combination against the same cyathostomin population. In the field study, anthelmintic treatments occurred when ten horses exceeded 100 eggs per gram. Fecal egg counts and efficacy evaluations were performed every two weeks. The two simulations utilized weather data as well as equine and parasite population parameters from the field study. The first simulation repeated the treatment schedule used in the field study over a 40 year period. The second evaluated efficacies of combination treatments using selective therapy over 40 years. In the field study, efficacies of MOX and both combination treatments were 100%. The egg reappearance period for MOX was 16 weeks, and the two combination treatments were 12 and 18 weeks. The first (46.7%) and last (40.1%) OBZ efficacies were not significantly different from each other. In the simulation study, the combination treatment delayed MOX resistance development compared to when MOX was used as a single active. This occurred despite the low efficacy of OBZ. The second set of simulations identified combination treatments used with selective therapy to be the most effective at delaying MOX resistance. Overall, this study supports the use of combination treatment against drug-resistant cyathostomins, when one of the actives exhibits high efficacy, and demonstrates benefits of this approach despite substantially lowered efficacy of the other active ingredient.
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Combination deworming for the control of double-resistant cyathostomin parasites – short and long term consequences
Veterinary Parasitology, 2018Co-Authors: J.a. Scare, Eugene T. Lyons, K.m. Wielgus, Martin K. NielsenAbstract:Abstract Equine cyathostomin are pervasive gastrointestinal parasites with wide-spread resistance to the benzimidazole and tetrahydropyrimidine drug classes worldwide. Combination deworming has been proposed as a more sustainable parasite control strategy. Simulation studies have found combination deworming to be effective in controlling drug resistant ovine trichostrongylid parasites. One equine study demonstrated an additive effect of a combination of Oxibendazole and pyrantel pamoate against cyathostomins. However, this is the only equine study evaluating combination therapy, and the effects of repeated combination treatments administered over time remain unknown. The purpose of this study was to observe the efficacy of repeated Oxibendazole/pyrantel pamoate combination therapy administered over one year against a cyathostomin population with resistance to benzimidazole and pyrantel products. Fecal egg counts were determined for the entire herd (N = 21) at the day of anthelmintic treatment and at two-week intervals for eight weeks post treatment. Starting efficacies of Oxibendazole (OBZ, 10 mg/kg) and pyrantel pamoate (PYR, 6.6 mg base/kg) were 66.7% and 63.3%, respectively. Hereafter, the herd was treated four times with an Oxibendazole/pyrantel pamoate combination, eight weeks apart, followed by repeating the single active treatments before concluding the study. While the first combination treatment exhibited an additive effect of the two active ingredients, this efficacy was not sustained over the course of the study. Mean fecal egg count reduction (FECR) was significantly greater for the first combination treatment (76.6%) than the second (42.6%, p = 0.0454), third (41.6%, p = 0.0318), and fourth (40.7%, p = 0.0372) combination treatments. The final single active mean FECRs were 42.3% for Oxibendazole, and 42.7% for pyrantel pamoate. These efficacies were not significantly different from the initial single active efficacies (OBZ, p = 0.4421; PYR, p = 0.8361). These results suggest that combination therapy against double resistant equine cyathostomin populations is not sustainable, when using actives with markedly decreased starting efficacies.
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Profiles of strongyle EPG values for Thoroughbred mares on 14 farms in Kentucky (2012–2013)
Veterinary Parasitology, 2014Co-Authors: Eugene T. Lyons, Martin K. Nielsen, Sharon C. Tolliver, Tetiana A. Kuzmina, I. I. Dzeverin, K.j. McdowellAbstract:Abstract The main purpose of the research was to determine if three weekly samplings would produce consistent results for low strongyle egg shedders, generally associated with older horses. Strongyle egg counts per gram of feces (EPG) were done for 661 Thoroughbred mares on 14 farms in 2012–2013 once a week for three consecutive weeks. None of the mares had been treated with ivermectin or moxidectin for more than 90 days and with fenbendazole, Oxibendazole, or pyrantel pamoate for more than 60 days. Strongyle EPG count data indicated that 38.3% of the mares were positive at first and second sampling, and 37.8% – at third sampling. There were 5.6–63.3% of horses positive per farm. Correlations between EPG count data in all three weeks are quite high (Rs = 0.84, p
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Characterization of the inflammatory response to anthelmintic treatment of ponies with cyathostominosis
Veterinary Journal, 2013Co-Authors: Martin K. Nielsen, Eugene T. Lyons, A. Betancourt, David W. Horohov, Stine JacobsenAbstract:Abstract Cyathostomins can cause a severe inflammation of equine large intestine characterized by substantial ventral edema and pronounced protein loss. Anthelmintic treatment of horses can result in a localized inflammatory response in the colonic mucosa of clinically normal horses. The aim of this study was to evaluate the systemic inflammatory response of ponies naturally infected with cyathostomins to single dose representatives of three anthelmintic drug classes, namely, Oxibendazole, pyrantel pamoate, and moxidectin. Thirty ponies aged between 1 and 18 years of age were allocated to one of three anthelmintic treatments groups. Anthelmintic efficacy was evaluated using the fecal egg count reduction test performed weekly between 2 and 8 weeks post-treatment. Inflammatory responses were evaluated on days 0, 1, 3, 5, and 14 after treatment using hematology, measurement of the acute phase inflammatory markers serum amyloid A, fibrinogen, haptoglobin, and iron, and real-time PCR measurement of expression of the genes for interleukins 1-β and −10, tumor necrosis factor-α, and interferon-γ. There were subtle inflammatory responses to treatment, but cytokine expression was significantly associated with the interaction term between treatment group and anthelmintic efficacy (P
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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)
Parasitology Research, 2011Co-Authors: Eugene T. Lyons, Sharon C. Tolliver, Tetiana A. Kuzmina, Sandra S. CollinsAbstract: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 objective was to compare these findings with those from earlier data on the efficacy of these three compounds on nematodes in foals in this geographical area. Efficacies (average) for the foals ranged for FBZ (10 mg/kg) from 50% to 100% (80%), for OBZ (10 mg/kg) from 75% to 100% (97%), and for PRT at 1× (6.6 mg base/kg) from 0% to 71% (2%) and at 2× (13.2 mg base/kg) 0% to 0% (0%). Although the efficacy varied among the drugs, combined data for all farms indicated a significant reduction of ascarid infections for FBZ ( p
J. Catherine Ngila - One of the best experts on this subject based on the ideXlab platform.
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Voltammetric Determination of a Benzimidazole Anthelmintic Mixture at a Poly(3-methylthiophene)-modified Glassy Carbon Electrode
South African journal of chemistry, 2020Co-Authors: Titus A.m. Msagati, J. Catherine NgilaAbstract:The voltammetric determination of benzimidazole anthelmintics at a glassy carbon rotating-disk electrode modified with poly(3-methylthiophene) is presented. The purpose of surface modification was to improve the sensitivity and limits of detection for determination of the compounds in a standard mixture. Thus, five compounds, namely thiabendazole, mebendazole, albendazole, fenbendazole and Oxibendazole have been studied using square wave voltammetry. It has been possible to resolve four of the compounds, mebendazole, fenbendazole, Oxibendazole and thiabendazole, in a mixture. Investigations of a number of parameters, including the mode of potential application, cathodic reduction versus anodic oxidation, the type of electrode, effect of pH and speed of electrode rotation, among others, are reported. South African Journal of Chemistry Vol.56 2003: 5-9
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Chemometric investigation of the effects of chemical properties and concentrations on the extractability of benzimidazoles with supported liquid membrane
African Journal of Agricultural Research, 2011Co-Authors: Titus Alfred Makudali Msagati, J. Catherine Ngila, Mathew Muzi Nindi, Bhekie B. MambaAbstract:Principle component analysis (PCA) and a two-way analysis of variance (ANOVA) were employed in the study of factors affecting extractability of benzimidazole anthelmintics using supported liquid membrane (SLM) in liver, kidney, milk and urine at four concentration levels. The SLM extraction process was monitored by liquid chromatography - mass spectrometer (LC-MS). The results showed that the extractability of benzimidazoles is dependent on both the concentration levels and the chemical properties of compounds. Based on chemical properties, extraction of the compounds from the liver matrix showed no significant difference (p = 0.05) for the following pairs; albendazole and Oxibendazole, thiabendazole and mebendazole, Oxibendazole and fenbendazole, and Oxibendazole and mebendazole. At some of the concentration levels, mainly between 1000 and 100, 100 and 10, and 10 and 1 µg/Kg, there was no significant difference. It was also found that, there was significant difference (at p = 0.05) in the extractability in milk between Oxibendazole and albendazole, and also Oxibendazole and fenbendazole. For milk also, the concentration range from 10 to 100 µg/L, showed no significant difference (p = 0.05). Urine matrix on the other hand, showed significant difference in the recoveries at all concentration levels.
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Voltammetric determination of a benzimidazole anthelmintic mixture at a poly(3-methylthiophene)-modified glassy carbon electrode
South African Journal of Chemistry, 2003Co-Authors: Titus Alfred Makudali Msagati, J. Catherine NgilaAbstract:The voltammetric determination of benzimidazole anthelmintics at a glassy carbon rotating-disk electrode modified with poly(3-methylthiophene) is presented. The purpose of surface modification was to improve the sensitivity and limits of detection for determination of the compounds in a standard mixture. Thus, five compounds, namely thiabendazole, mebendazole, albendazole, fenbendazole and Oxibendazole have been studied using square wave voltammetry. It has been possible to resolve four of the compounds, mebendazole, fenbendazole, Oxibendazole and thiabendazole, in a mixture. Investigations of a number of parameters, including the mode of potential application, cathodic reduction versus anodic oxidation, the type of electrode, effect of pH and speed of electrode rotation, among others, are reported.
E T Lyons - One of the best experts on this subject based on the ideXlab platform.
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Strongyloides westeri and Parascaris equorum: Observations in field studies in Thoroughbred foals on some farms in Central Kentucky, USA
Helminthologia, 2014Co-Authors: E T Lyons, S C TolliverAbstract:Observations were made on the intestinal threadworm ( Strongyloides westeri ) and ascarid ( Parascaris equorum ) in field studies in 373 Thoroughbred foals on nine farms in Central Kentucky (USA) in 2013. Qualitative examination was made of feces of the foals for presence of S. westeri and P. equorum eggs. The main purpose of the prevalence study was to obtain current data on S. westeri in Thoroughbred foals. This was done to compare these findings with earlier studies in this geographical area where the prevalence of this parasite has been very low the last several decades. All the foals except on one farm had been treated one or more times with a parasiticide before the study. Prevalence of S. westeri in foals was 0 to 3 % on two farms, 6 to 9 % on three farms, and 20 to 51 % on four farms. The prevalence of P. equorum in foals was 0 to 14 % on three farms, 27 to 38 % on three farms, and 46 to 51 % on three farms. Effect of drugs given before the current study, on the prevalence of the two parasitic nematode species, is discussed. Also, three field tests were done by the present authors to evaluate activity of three individual or combination of drugs against ascarids. Evaluation was somewhat limited because, on two of the farms, a relatively small number of foals was passing ascarid eggs before treatment. However, Oxibendazole and Oxibendazole/piperazine combination were much more efficacious than fenbendazole.
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control of cambendazole resistant small strongyles population s with Oxibendazole in a pony band an 8 year field test 1984 1992
Veterinary Parasitology, 1994Co-Authors: E T Lyons, J H Drudge, S C Tolliver, S Stamper, T W Swerczek, D E GranstromAbstract:Abstract Studies in a band of ponies harboring Population S benzimidazole-resistant small strongyles were initiated in 1974 and have continued for 18 years. Treatment (bimonthly) was with cambendazole for the first 4 years and with Oxibendazole (OBZ) for the next 14 years. Data on the first 10 years have been published. The present investigation includes the last 8 years (4 October 1984-11 September 1992), which are the seventh through fourteenth years, of treatment with OBZ. Pre- and posttreatment mean counts of strongyle eggs (epg) and larvae (lpg) per gram of feces were determined biweekly during the current study to monitor the efficacy of OBZ. The average annual percent reductions of epg counts effected by OBZ treatments were 51%, 53%, 38%, 38%, 39%, 28%, 40%, and 19% for the seventhth through fourteenth years, respectively. Similar levels of reductions were observed for lpg counts. Although OBZ was initially highly effective on this population of small strongyles, epg and lpg counts gradually declined, but have remained more or less constant since the fifth year of research. However, reductions of the counts were the lowest for the last year of the study.
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critical tests of thiabendazole Oxibendazole and oxfendazole for drug resistance of population b equine small strongyles 1989 and 1990
American Journal of Veterinary Research, 1993Co-Authors: S C Tolliver, J H Drudge, E T Lyons, S Stamper, D E GranstromAbstract:: Critical tests were conducted in horses (n = 11) with naturally acquired infections of benzimidazole (BZ)-resistant population-B small strongyles in 1989 and 1990. Anthelmintics administered were thiabendazole (44 mg/kg of body weight, n = 4), Oxibendazole (10 mg/kg, n = 3), and oxfendazole (OFZ, 10 mg/kg; n = 4). All compounds were paste formulations administered orally except for 1 of the OFZ treatments, which was a suspension formulation given by stomach tube. Aggregate mean efficacy was calculated for all species of small strongyles, drug-resistant and non-resistant. The highest efficacy was for Oxibendazole (98%) and OFZ (94%); efficacy for thiabendazole was 63%. Five genera and 16 species of small strongyles were recovered from the 11 horses, ranging from 7 to 13 species (mean, 11). Of these, 7 species were found to have resistance in variable degrees to most of the anthelmintics. These strongyles were Cyathostomum catinatum, Cyathostomum coronatum, Cylicocyclus nassatus, Cylicostephanus calicatus, Cylicostephanus goldi, Cylicostephanus longibursatus, and Cylicostephanus minutus. The large strongyle, Strongylus vulgaris, was present in all 11 test horses, and efficacy was 100% for all drugs. Seven of the BZ-treated foals (at least 1 horse from each BZ-treatment group), were infected with S edentatus; removal was 100%.
Sharon C. Tolliver - One of the best experts on this subject based on the ideXlab platform.
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Profiles of strongyle EPG values for Thoroughbred mares on 14 farms in Kentucky (2012–2013)
Veterinary Parasitology, 2014Co-Authors: Eugene T. Lyons, Martin K. Nielsen, Sharon C. Tolliver, Tetiana A. Kuzmina, I. I. Dzeverin, K.j. McdowellAbstract:Abstract The main purpose of the research was to determine if three weekly samplings would produce consistent results for low strongyle egg shedders, generally associated with older horses. Strongyle egg counts per gram of feces (EPG) were done for 661 Thoroughbred mares on 14 farms in 2012–2013 once a week for three consecutive weeks. None of the mares had been treated with ivermectin or moxidectin for more than 90 days and with fenbendazole, Oxibendazole, or pyrantel pamoate for more than 60 days. Strongyle EPG count data indicated that 38.3% of the mares were positive at first and second sampling, and 37.8% – at third sampling. There were 5.6–63.3% of horses positive per farm. Correlations between EPG count data in all three weeks are quite high (Rs = 0.84, p
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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)
Parasitology Research, 2011Co-Authors: Eugene T. Lyons, Sharon C. Tolliver, Tetiana A. Kuzmina, Sandra S. CollinsAbstract: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 objective was to compare these findings with those from earlier data on the efficacy of these three compounds on nematodes in foals in this geographical area. Efficacies (average) for the foals ranged for FBZ (10 mg/kg) from 50% to 100% (80%), for OBZ (10 mg/kg) from 75% to 100% (97%), and for PRT at 1× (6.6 mg base/kg) from 0% to 71% (2%) and at 2× (13.2 mg base/kg) 0% to 0% (0%). Although the efficacy varied among the drugs, combined data for all farms indicated a significant reduction of ascarid infections for FBZ ( p
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Prevalence of anthelmintic resistant cyathostomes on horse farms
Javma-journal of The American Veterinary Medical Association, 2004Co-Authors: Ray M. Kaplan, Eugene T. Lyons, Thomas R Klei, Guy D. Lester, Charles H. Courtney, Dennis D French, Sharon C. Tolliver, Anand N. Vidyashankar, Ying ZhaoAbstract:Objective-To determine prevalence of anthelmintic resistance in cyathostome nematodes of horses in the southern United States. Design-Cross-sectional study. Animals-786 horses on 44 farms and stables in Georgia, South Carolina, Florida, Kentucky, and Louisiana. Procedure-Fecal egg count (FEC) reduction tests were performed on 44 large farms and stables. Horses on each farm were treated with an oral paste formulation of fenbendazole, Oxibendazole, pyrantel pamoate, or ivermectin at recommended label dosages. A mixed linear model was fitted to the percentage reduction in FEC, accounting for differences among farms, states, ages, treatments, and treatment by state interactions. Results-By use of a conservative measure of resistance (< 80% reduction), the percentage of farms with anthelmintic-resistant cyathostomes was 977%, 0%, 53.5%, and 40.5% for fenbendazole, ivermectin, Oxibendazole, and pyrantel pamoate, respectively. Mean percentage reductions in FEC for all farms were 24.8%, 99.9%, 73.8%, and 78.6% for fenbendazole, ivermectin, Oxibendazole, and pyrantel pamoate, respectively. Pairwise contrasts between states for each treatment revealed that in almost all instances, there were no significant differences in results between states. Conclusions and Clinical Relevance-The prevalence of resistance found in this study was higher than that reported previously, suggesting that anthelmintic resistance in equine cyathostomes is becoming a major problem. Furthermore, data from these 5 southern states, which are geographically and physiographically distinct, were remarkably similar. This suggests that drug resistance in cyathostomes is highly prevalent throughout the entire southern United States and probably nationwide.
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Continuance of studies on Population S benzimidazole-resistant small strongyles in a Shetland pony herd in Kentucky: effect of pyrantel pamoate (1992-1999).
Veterinary Parasitology, 2001Co-Authors: Eugene T. Lyons, Sharon C. Tolliver, Drudge Jh, S. S. Collins, Thomas W. SwerczekAbstract:Abstract Research on benzimidazole-resistant Population S small strongyles began in a Shetland pony herd in 1974 at the University of Kentucky and has continued for over 25 years. The present update, for the period 1992–1999, evaluated activity of pyrantel pamoate (PRT) in field tests in the pony herd. Additional critical tests with PRT and Oxibendazole (OBZ) were done in foals born in the herd. Activity of PRT was initially excellent in field tests, based on epg/lpg count data, but declined rapidly during the second full year of pyrantel treatments. Critical test data for small strongyles indicated efficacies of PRT were about 60% at the beginning of the present observations and this intermediate level of removal continued throughout the seven-year period except for 1994 (75%). Unusual was the finding that field test epg/lpg data on small strongyles indicated much lower activity of PRT than found in worm count data in critical tests. The previously reported ineffective activity of OBZ on this population of small strongyles continued. Data are presented on prevalence and drug activity on several species of internal parasites besides small strongyles.
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A study (1977–1992) of population dynamics of endoparasites featuring benzimidazole-resistant small strongyles (Population S) in Shetland ponies
Veterinary Parasitology, 1996Co-Authors: Eugene T. Lyons, Sharon C. Tolliver, Drudge Jh, S Stamper, Thomas W. Swerczek, D E GranstromAbstract:Abstract Critical tests (91) were done between 1977 and 1992 in Shetland ponies to evaluate drug susceptibility and population dynamics (present paper) of endoparasites. The test ponies, most less than 1 year old, were from a herd where older animals were treated every 8 weeks initially with cambendazole (CBZ) (1974–1978) and then with Oxibendazole (OBZ) (1978–1992). Previous field test data (1974–1992) on older ponies in the breeding herd indicated the presence of benzimidazole (BZ) resistant small strongyles. Data on population dynamics from the present critical tests indicated that 28 species of small strongyles persisted over the study period in spite of initial susceptibility and later refractiveness of six species to both CBZ and OBZ. Changes in intensities and other aspects were observed for the six BZ-resistant species ( Cyathostomum catinatum, Cyathostomum coronatum, Cylicocyclus nassatus, Cylicostephanus calicatus, Cylicostephanus goldi , and Cylicostephanus longibursatus ). Variabilities, some striking, were found in prevalence and intensity in bots, stomach worms, ascarids, eyeworms, large strongyles, pinworms and tapeworms.
