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E. T. Lyons - One of the best experts on this subject based on the ideXlab platform.
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Strongyloides westeri worm and egg counts in naturally infected young horses
Veterinary Parasitology, 2017Co-Authors: F L Miller, E. T. Lyons, Jennifer L Bellaw, M K NielsenAbstract:Abstract Strongyloides westeri is a threadworm parasite found in the small intestine mainly in foals at up to about 4 months of age. This parasite is associated with small intestinal enteritis and diarrhea as well as skin irritation and a clinical syndrome called “frenzied behavior” due to percutaneous invasion. The aim of this study was to investigate S. westeri parasite burdens in age groups older than the initial lactogenic transmission phase. Secondary aims were to examine the impact of host age and gender on worm burden and egg output in naturally infected foals. Thirteen foals were enrolled in the study, exposed to natural infection with S. westeri and were humanely euthanized at ages ranging from 89 to 221 days old. Egg counts per gram of feces were determined using the Mini-FLOTAC method. Worms were retrieved from the mucosa of the anterior half of the small intestine using a digestion method and enumerated. The foals were all observed to be healthy with no signs of parasitic disease. Foals at 4–5 months of age had significantly higher S. westeri worm and egg counts compared to those aged 6–8 months (p
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Strongyloides westeri worm and egg counts in naturally infected young horses
Veterinary Parasitology, 2017Co-Authors: F Miller, Jennifer L Bellaw, E. T. Lyons, Martin K. NielsenAbstract:Strongyloides westeri is a threadworm parasite found in the small intestine mainly in foals at up to about 4 months of age. This parasite is associated with small intestinal enteritis and diarrhea as well as skin irritation and a clinical syndrome called "frenzied behavior" due to percutaneous invasion. The aim of this study was to investigate S. westeri parasite burdens in age groups older than the initial lactogenic transmission phase. Secondary aims were to examine the impact of host age and gender on worm burden and egg output in naturally infected foals. Thirteen foals were enrolled in the study, exposed to natural infection with S. westeri and were humanely euthanized at ages ranging from 89 to 221days old. Egg counts per gram of feces were determined using the Mini-FLOTAC method. Worms were retrieved from the mucosa of the anterior half of the small intestine using a digestion method and enumerated. The foals were all observed to be healthy with no signs of parasitic disease. Foals at 4-5 months of age had significantly higher S. westeri worm and egg counts compared to those aged 6-8 months (p<0.05). Fecal egg counts were significantly associated with worm counts (p=0.0045). While egg and worm counts declined markedly in the 6-8 month age range, they were not eliminated completely. This could either reflect a new infection acquired orally or transcutaneously, or a subset of adult intestinal parasites acquired via the lactogenic route and surviving for longer time periods. This study provided new information about S. westeri infection patterns in young horses at 4-8 months of age.
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Prevalence of patent Strongyloides westeri infections in Thoroughbred foals in 2014
Parasitology Research, 2014Co-Authors: E. T. Lyons, S. C. TolliverAbstract:The prevalence of patent Strongyloides westeri infections was determined by examination for eggs in fecal samples collected from 513 Thoroughbred (TB) foals between February 25 and June 3, 2014. The study was conducted with 244 colts and 269 fillies from 11 well-managed farms in Central Kentucky. Foals ranged from 17 to 117 days of age and had never been dewormed. The mean prevalence of patent S. westeri infection was 30 % (156/513 foals). This prevalence was substantially greater than historical reports from the same sampling area during the late 1990s and early 2000s. It is hypothesized that this change is attributable to diminished use of ivermectin in foals due to concerns about macrocyclic lactone resistance in Parascaris equorum.
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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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Parasite field study in central Kentucky on thoroughbred foals (born in 2004) treated with pyrantel tartrate daily and other parasiticides periodically
Parasitology Research, 2007Co-Authors: E. T. Lyons, S. C. Tolliver, R. A. Rathgeber, S. S. CollinsAbstract:Foals (79), born in 2004 on three thoroughbred horse farms (C, M, and S) in central Kentucky, were fed pyrantel tartrate daily, beginning at about 3 months of age. In addition, other parasiticides [fenbendazole (FBZ), ivermectin (IVM) alone or with praziquantel (PRAZ), oxibendazole (OBZ), pyrantel pamoate (PRT), and moxidectin (MOX)] were given periodically. All treatments were administered by farm personnel. Over a 14-month period, from May 2004 to July 2005, collections ( n =989) of feces were made from the foals for determination of presence of internal parasite eggs/oocysts by qualitative and/or quantitative methods. Conclusions on drug activity are based necessarily on considering the combined effect of pyrantel tartrate and the other compounds. For small strongyles, this was related to which specific additional compound was given. Based on the percentage of foals with strongyle-egg-positive feces and/or the level of eggs per gram of feces (EPG) counts for the foals after treatment, drug activity on small strongyles was highest to lowest for MOX, IVM and IVM/PRAZ, FBZ, OBZ, PRT, and FBZ (2× for 5 days). The macrocyclic lactones (MOX and IVM) were highly superior to the other compounds. Some of the strongyle counts were high (over 2,000), especially on one farm (S), during periods when foals received only pyrantel tartrate, but a few days after administration of therapeutic dose rates of the drugs IVM or MOX, they were negative or very low. Ascarid eggs were present in feces of three foals after treatment with a combination of IVM and PRAZ. The qualitative method was more efficient than the quantitative method in detection of ascarid and strongyle eggs in the feces. Prevalence of eggs of ascarids ( Parascaris equorum ) was low (0, 4, and 31%), of strongyles high (80, 100, and 100%), of Strongyloides westeri very low (only one infected foal), and oocysts of Eimeria leuckarti medium to high (36, 41, and 85%) for the three farms, C, M, and S, respectively. It is uncertain whether the low ascarid prevalence was from activity of pyrantel tartrate and/or the other drugs or to a limited source of infective eggs.
S. S. Collins - One of the best experts on this subject based on the ideXlab platform.
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Parasite field study in central Kentucky on thoroughbred foals (born in 2004) treated with pyrantel tartrate daily and other parasiticides periodically
Parasitology Research, 2007Co-Authors: E. T. Lyons, S. C. Tolliver, R. A. Rathgeber, S. S. CollinsAbstract:Foals (79), born in 2004 on three thoroughbred horse farms (C, M, and S) in central Kentucky, were fed pyrantel tartrate daily, beginning at about 3 months of age. In addition, other parasiticides [fenbendazole (FBZ), ivermectin (IVM) alone or with praziquantel (PRAZ), oxibendazole (OBZ), pyrantel pamoate (PRT), and moxidectin (MOX)] were given periodically. All treatments were administered by farm personnel. Over a 14-month period, from May 2004 to July 2005, collections ( n =989) of feces were made from the foals for determination of presence of internal parasite eggs/oocysts by qualitative and/or quantitative methods. Conclusions on drug activity are based necessarily on considering the combined effect of pyrantel tartrate and the other compounds. For small strongyles, this was related to which specific additional compound was given. Based on the percentage of foals with strongyle-egg-positive feces and/or the level of eggs per gram of feces (EPG) counts for the foals after treatment, drug activity on small strongyles was highest to lowest for MOX, IVM and IVM/PRAZ, FBZ, OBZ, PRT, and FBZ (2× for 5 days). The macrocyclic lactones (MOX and IVM) were highly superior to the other compounds. Some of the strongyle counts were high (over 2,000), especially on one farm (S), during periods when foals received only pyrantel tartrate, but a few days after administration of therapeutic dose rates of the drugs IVM or MOX, they were negative or very low. Ascarid eggs were present in feces of three foals after treatment with a combination of IVM and PRAZ. The qualitative method was more efficient than the quantitative method in detection of ascarid and strongyle eggs in the feces. Prevalence of eggs of ascarids ( Parascaris equorum ) was low (0, 4, and 31%), of strongyles high (80, 100, and 100%), of Strongyloides westeri very low (only one infected foal), and oocysts of Eimeria leuckarti medium to high (36, 41, and 85%) for the three farms, C, M, and S, respectively. It is uncertain whether the low ascarid prevalence was from activity of pyrantel tartrate and/or the other drugs or to a limited source of infective eggs.
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Field studies on endoparasites of Thoroughbred foals on seven farms in central Kentucky in 2004
Parasitology Research, 2006Co-Authors: S. S. CollinsAbstract:Fecal samples ( n =1,584) for a parasite study were collected from Thoroughbred foals ( n =349), 28 to 330 days old, on seven farms in central Kentucky during 49 monthly trips from May to October, November, or December 2004. The main purpose was to determine possible drug resistance of ascarids, also of strongyles, to ivermectin (IVM) and other commercially available compounds [fenbendazole, moxidectin (MOX), oxibendazole (OBZ), and pyrantel pamoate]. In addition, interest was on prevalence of foal parasites. Qualitative data were obtained by recording presence or absence of ascarid and strongyle eggs in feces from 7 to 25 days after treatment of some of the foals. None of the compounds completely eliminated ascarid eggs in feces of all foals posttreatment. Activity on ascarids was significantly the highest for OBZ and lowest for IVM. Activity on strongyles was significantly higher for IVM and MOX than for the other compounds. Prevalence (mean percentage of foals infected) was recorded for eggs of Parascaris equorum (39%), of strongyles (32%), and of Strongyloides westeri (2%) and oocysts of Eimeria leuckarti (28%) in feces of foals. One or more foals had infections of P. equorum on six farms (86%), strongyles on seven farms (100%), S. westeri on two farms (29%), and E. leuckarti on six farms (86%). The oldest foal infected with E. leuckarti was 301 days of age. Comparison was made on the prevalence of parasites in foals on five of the same farms in the 2004 study, which were part of a similar 14-farm project in 2003 (Lyons and Tolliver in Parasitol Res ( 2004 ) 92:400–404).
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Transmission of some species of internal parasites in horses born in 1990, 1991, and 1992 in the same pasture on a farm in central Kentucky.
Veterinary parasitology, 1994Co-Authors: S Stamper, J H Drudge, D E Granstrom, S. S. CollinsAbstract:Studies were conducted on transmission of natural infections of several species of internal parasites in horses born and kept on the same pasture on a farm in central Kentucky. Data for the first year (1989) of a 4 year study on this farm have been published recently. The present research represents the second (1990), third (1991), and fourth (1992) years of the investigation. The number of animals (n = 28) examined varied from eight born in 1990 to ten each born in 1991 and 1992. For each year, examination was made of one horse per month, beginning in June of the year of birth and extending through January (1990) or March (1991 and 1992) the following year. Ages of the horses at necropsy ranged from 87 to 251 days. Major parasites present and months of recovery were: bots--Gasterophilus intestinalis in the mouth September-January and in the stomach August-March; stomach worms--Trichostrongylus axei in August and November, Habronema spp. (immature) in July-November and January, and Habronema muscae in October, January, and February; ascarids--Parascaris equorum in the small intestine and lungs all months; intestinal threadworms--Strongyloides westeri in all months except February; large strongyles--Strongylus vulgaris in the large intestine in all months except July and August and in the cranial mesenteric artery in all months, and Strongylus edentatus in the large intestine in January and in the ventral abdominal wall in all months; pinworms--Oxyuris equi in June and January-March; tapeworms--Anoplocephala perfoliata in August-October and December-March; and eyeworms--Thelazia lacrymalis August-February. Yearly differences and similarities of infections in the horses are discussed. The value of this type of research is mentioned.
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natural infections of Strongyloides westeri prevalence in horse foals on several farms in central kentucky in 1992
Veterinary Parasitology, 1993Co-Authors: E. T. Lyons, D E Granstrom, S. C. Tolliver, Harold J Drudge, S. S. CollinsAbstract:Abstract During the period 28 February–1 July 1992, fecal samples were collected and examined for eggs of Strongyloides westeri once from each of 382 horse foals (364 Thoroughbreds, 16 Standardbreds, one Lippizaner, and one draft-type horse) in central Kentucky. Ages of the foals at the time of sampling ranged from 7 to 63 days (mean 22 days). The nine farms in the study were considered to have overall excellent deworming programs. None of the foals had been treated with an antiparasitic compound before the study. Eggs of S. westeri were found in 6% (22 of 382) of the foals on 78% (7 of 9) of the farms. Current prevalence of this parasite in foals is discussed relative to studies before the availability and usage of effective drugs.
S. C. Tolliver - One of the best experts on this subject based on the ideXlab platform.
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Prevalence of patent Strongyloides westeri infections in Thoroughbred foals in 2014
Parasitology Research, 2014Co-Authors: E. T. Lyons, S. C. TolliverAbstract:The prevalence of patent Strongyloides westeri infections was determined by examination for eggs in fecal samples collected from 513 Thoroughbred (TB) foals between February 25 and June 3, 2014. The study was conducted with 244 colts and 269 fillies from 11 well-managed farms in Central Kentucky. Foals ranged from 17 to 117 days of age and had never been dewormed. The mean prevalence of patent S. westeri infection was 30 % (156/513 foals). This prevalence was substantially greater than historical reports from the same sampling area during the late 1990s and early 2000s. It is hypothesized that this change is attributable to diminished use of ivermectin in foals due to concerns about macrocyclic lactone resistance in Parascaris equorum.
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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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Parasite field study in central Kentucky on thoroughbred foals (born in 2004) treated with pyrantel tartrate daily and other parasiticides periodically
Parasitology Research, 2007Co-Authors: E. T. Lyons, S. C. Tolliver, R. A. Rathgeber, S. S. CollinsAbstract:Foals (79), born in 2004 on three thoroughbred horse farms (C, M, and S) in central Kentucky, were fed pyrantel tartrate daily, beginning at about 3 months of age. In addition, other parasiticides [fenbendazole (FBZ), ivermectin (IVM) alone or with praziquantel (PRAZ), oxibendazole (OBZ), pyrantel pamoate (PRT), and moxidectin (MOX)] were given periodically. All treatments were administered by farm personnel. Over a 14-month period, from May 2004 to July 2005, collections ( n =989) of feces were made from the foals for determination of presence of internal parasite eggs/oocysts by qualitative and/or quantitative methods. Conclusions on drug activity are based necessarily on considering the combined effect of pyrantel tartrate and the other compounds. For small strongyles, this was related to which specific additional compound was given. Based on the percentage of foals with strongyle-egg-positive feces and/or the level of eggs per gram of feces (EPG) counts for the foals after treatment, drug activity on small strongyles was highest to lowest for MOX, IVM and IVM/PRAZ, FBZ, OBZ, PRT, and FBZ (2× for 5 days). The macrocyclic lactones (MOX and IVM) were highly superior to the other compounds. Some of the strongyle counts were high (over 2,000), especially on one farm (S), during periods when foals received only pyrantel tartrate, but a few days after administration of therapeutic dose rates of the drugs IVM or MOX, they were negative or very low. Ascarid eggs were present in feces of three foals after treatment with a combination of IVM and PRAZ. The qualitative method was more efficient than the quantitative method in detection of ascarid and strongyle eggs in the feces. Prevalence of eggs of ascarids ( Parascaris equorum ) was low (0, 4, and 31%), of strongyles high (80, 100, and 100%), of Strongyloides westeri very low (only one infected foal), and oocysts of Eimeria leuckarti medium to high (36, 41, and 85%) for the three farms, C, M, and S, respectively. It is uncertain whether the low ascarid prevalence was from activity of pyrantel tartrate and/or the other drugs or to a limited source of infective eggs.
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Prevalence of parasite eggs (Strongyloides westeri, Parascaris equorum, and strongyles) and oocysts (Emeria leuckarti) in the feces of Thoroughbred foals on 14 farms in central Kentucky in 2003
Parasitology Research, 2004Co-Authors: E. T. Lyons, S. C. TolliverAbstract:Prevalence of internal parasites was determined by fecal examination for eggs and oocysts in Thoroughbred foals in central Kentucky in 2003. Fecal samples were examined from 733 foals on 14 farms. This included 70 trips to the farms and a total of 2,346 fecal samplings. Monthly collection of fecal samples was begun for four farms in February, six in March, three in April, and one farm in May. Termination of the study for all farms was the end of July. A criterion was that the foals be at least 10 days old for initial samplings. If available, the same foals were sampled each time, in addition to foals born in the interim between farm visits. Ages of the foals for the complete study varied from 10 to 223 days. Prevalence (mean %) was determined for eggs of Strongyloides westeri (1.5%), Parascaris equorum (22.4%), and strongyles (27.6%) and for oocysts of Eimeria leuckarti (41.6%) in feces of foals. Foals had infections of S. westeri on six farms (42.9%), of P. equorum on 12 farms (86%), and of strongyles and E. leuckarti on all 14 farms (100%).
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natural infections of Strongyloides westeri prevalence in horse foals on several farms in central kentucky in 1992
Veterinary Parasitology, 1993Co-Authors: E. T. Lyons, D E Granstrom, S. C. Tolliver, Harold J Drudge, S. S. CollinsAbstract:Abstract During the period 28 February–1 July 1992, fecal samples were collected and examined for eggs of Strongyloides westeri once from each of 382 horse foals (364 Thoroughbreds, 16 Standardbreds, one Lippizaner, and one draft-type horse) in central Kentucky. Ages of the foals at the time of sampling ranged from 7 to 63 days (mean 22 days). The nine farms in the study were considered to have overall excellent deworming programs. None of the foals had been treated with an antiparasitic compound before the study. Eggs of S. westeri were found in 6% (22 of 382) of the foals on 78% (7 of 9) of the farms. Current prevalence of this parasite in foals is discussed relative to studies before the availability and usage of effective drugs.
Rogério O. Carvalho - One of the best experts on this subject based on the ideXlab platform.
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In vitro predatory activity of nematophagous fungi and after passing through gastrointestinal tract of equine on infective larvae of Strongyloides westeri
Parasitology Research, 2010Co-Authors: Juliana M. Araujo, Jackson V. Araújo, Fabio R. Braga, Rogério O. CarvalhoAbstract:Three isolates of predator fungi Duddingtonia flagrans (AC001), Monacrosporium thaumasium (NF34), and Arthrobotrys robusta (I-31) were assessed in in vitro test regarding the capacity of prey infective larvae (L_3) Strongyloides westeri . Compared to control, without fungus, there was a significant decrease ( P 0.01) in vitro test. Linear regression coefficients of treated and control groups were −0.21 for control, −0.32 for D. flagrans , −0.34 for M. thaumasium , and −0.22 for A. robusta . In the following, isolates AC001 and NF34 were assessed in vivo regarding the capacity of supporting the passage through equine gastrointestinal tract without loss of ability of preying infective larvae S. westeri . Fungal isolates survived the passage and were efficient in preying L_3 since the first 12 h of collection ( P
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in vitro predatory activity of nematophagous fungi and after passing through gastrointestinal tract of equine on infective larvae of Strongyloides westeri
Parasitology Research, 2010Co-Authors: Juliana Milani Araujo, Fabio Ribeiro Braga, Jackson Victor De Araújo, Rogério O. CarvalhoAbstract:Three isolates of predator fungi Duddingtonia flagrans (AC001), Monacrosporium thaumasium (NF34), and Arthrobotrys robusta (I-31) were assessed in in vitro test regarding the capacity of prey infective larvae (L(3)) Strongyloides westeri. Compared to control, without fungus, there was a significant decrease (P 0.01) in vitro test. Linear regression coefficients of treated and control groups were -0.21 for control, -0.32 for D. flagrans, -0.34 for M. thaumasium, and -0.22 for A. robusta. In the following, isolates AC001 and NF34 were assessed in vivo regarding the capacity of supporting the passage through equine gastrointestinal tract without loss of ability of preying infective larvae S. westeri. Fungal isolates survived the passage and were efficient in preying L(3) since the first 12 h of collection (P < 0.01) in relation to the control group (without fungus). Compared to control, there was a significant decrease (P < 0.01) of 76.4% and 76.7% (12 h), 86.4% and 85.9% (24 h), 88.3% and 87.7% (48 h), and 89.9% and 87.2% (72 h) in means of infective larvae S. westeri recovered from treatments with isolates AC001 and NF34, respectively. Linear regression coefficients of L(3) of recovered S. westeri regarding the collections due to time were 1.93 for control, -3.52 for AC001, and -2.64 for NF34. Fungi D. flagrans and M. thaumasium (NF34) have demonstrated to be promising for use in the biological control of equine parasite S. westeri.
Martin K. Nielsen - One of the best experts on this subject based on the ideXlab platform.
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Anthelmintic efficacy of single active and combination products against commonly occurring parasites in foals
Veterinary Parasitology, 2019Co-Authors: L.h. Morris, Stephen Colgan, Dave M. Leathwick, Martin K. NielsenAbstract:Abstract Parasite control in foals is complicated by the concurrent presence of biologically diverse parasites with differing levels of anthelmintic resistance. Several combination anthelmintic products are available for use in horses, but information on their efficacies against important equine parasites is scarce. Two trials were performed in New Zealand during 2008 and 2011 on four different farms with substantially different anthelmintic treatment histories. The first trial evaluated the efficacy of an ivermectin/praziquantel/oxibendazole combination, a single active oxibendazole, and a single-active macrocyclic lactone (ML) in 49 foals located on three farms. The second trial evaluated two combination anthelmintic products and three single-active ML products and enrolled a total of 110 foals on three farms. Foals in the second trial were allocated to one of six anthelmintic treatment groups; oxfendazole/pyrantel embonate, pyrantel embonate/ivermectin/praziquantel, ivermectin/praziquantel, abamectin/praziquantel, moxidectin/praziquantel, and a placebo-treated control. In both trials, foals were monitored monthly prior to treatment, and fecal egg counts (FECs) of Parascaris spp., strongylid, and Strongyloides westeri were determined. A “rolling enrolment” process was implemented whereby foals were systematically allocated to a treatment group and treated with the corresponding anthelmintic following the first appearance of Parascaris spp. eggs in the faeces. A generalised linear model was used to evaluate the effect of farm and treatment on Day14 FEC (ln) for each parasite. Three different FECR calculation methods were employed as follows; i) FECR(T) pre and post treatment ii) FECR (C) in the treated group compared with control, and iii) FECR (P) pre- and post- treatment in the treated and control groups. Across both trials, treatment with ML single active products failed to achieve >95% reduction in Parascaris spp. FEC on two of three farms. The pyrantel embonate/oxfendazole and ivermectin/ praziquantel/oxibendazole combinations demonstrated full efficacy against Parascaris spp. This is in contrast to the anti-strongylid efficacies determined, where the pyrantel embonate/oxfendazole combination and single active oxibendazole had reduced efficacy on one farm, while the macrocyclic lactones generally had good efficacy. Strongyloides egg counts were sporadic in both trials, and allowed limited insight into anthelmintic efficacy. The study illustrated the importance of keeping an untreated or placebo-treated control group in studies evaluating anti-Parascaris efficacy and it demonstrated the utility of a rolling enrolment procedure, where foals are enrolled over the course of a defined period of time. Furthermore, the study demonstrated the value of a farm specific FECR monitoring programme and the complexity of parasite control in foals, where combination anthelmintic products can be employed to target multiple species of parasites.
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Strongyloides westeri worm and egg counts in naturally infected young horses
Veterinary Parasitology, 2017Co-Authors: F Miller, Jennifer L Bellaw, E. T. Lyons, Martin K. NielsenAbstract:Strongyloides westeri is a threadworm parasite found in the small intestine mainly in foals at up to about 4 months of age. This parasite is associated with small intestinal enteritis and diarrhea as well as skin irritation and a clinical syndrome called "frenzied behavior" due to percutaneous invasion. The aim of this study was to investigate S. westeri parasite burdens in age groups older than the initial lactogenic transmission phase. Secondary aims were to examine the impact of host age and gender on worm burden and egg output in naturally infected foals. Thirteen foals were enrolled in the study, exposed to natural infection with S. westeri and were humanely euthanized at ages ranging from 89 to 221days old. Egg counts per gram of feces were determined using the Mini-FLOTAC method. Worms were retrieved from the mucosa of the anterior half of the small intestine using a digestion method and enumerated. The foals were all observed to be healthy with no signs of parasitic disease. Foals at 4-5 months of age had significantly higher S. westeri worm and egg counts compared to those aged 6-8 months (p<0.05). Fecal egg counts were significantly associated with worm counts (p=0.0045). While egg and worm counts declined markedly in the 6-8 month age range, they were not eliminated completely. This could either reflect a new infection acquired orally or transcutaneously, or a subset of adult intestinal parasites acquired via the lactogenic route and surviving for longer time periods. This study provided new information about S. westeri infection patterns in young horses at 4-8 months of age.
