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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.
A field survey on the distribution of strongyle infections of horses in Sweden and factors affecting faecal egg counts. Faecal egg counts were performed during the first quarter of 1995 on samples from 1183 horses of varying breeds, ages and gender on 110 farms in 3 regions of Sweden. The majority of the horses had been treated with ivermectin or pyrantel when stabled the previous autumn. The risk of reinfection with strongyles between treatment and sampling was therefore considered to be minimal. Consequently, the results reflect primarily the occurrence of worms originating from inhibited strongyle larvae refractory to anthelmintic treatment. A total of 922 (78%) individuals were found to shed strongyle eggs,...
Comparative efficacy evaluation of moxidectin gel and ivermectin paste against internal parasites of equines in Brazil. A total of 24 male and female equines of mixed breed, 10-20 months of age and naturally infected with internal parasites was utilized in a controlled test to evaluate the efficacy of a moxidectin 2% gel formulation at the dosage of 0.4 mg moxidectin per kg of live weight and an ivermectin 1.87% commercial paste formulation at the dosage 0.2 mg ivermectin per kg applied orally. Animals were allocated into three groups of eight horses each based on pre-treatment eggs per gram (EPG) counts and treatments were randomized among the groups. One group was kept as untreated controls. One animal in the...
Efficacy of a 2 per cent moxidectin gel against gastrointestinal parasites of ponies. The efficacy of moxidectin was evaluated in young ponies naturally infected with gastrointestinal parasites. Eight animals were treated orally with moxidectin at 0.4 mg/kg bodyweight and eight received only the vehicle. They were all necropsied two weeks later. Faecal samples were examined daily for egg counts and larval cultures. Parasites were recovered from total faecal samples collected daily and from the gastrointestinal tracts at necropsy. Moxidectin reduced the strongyle egg counts by > 99 per cent from three days after treatment but some individuals remained positive for 10 days. Th...
Persistence of the efficacy of a moxidectin gel on the establishment of cyathostominae in horses. A controlled trial was carried out to evaluate the persistence of the effect against small strongyles of a 2 per cent moxidectin gel administered orally to foals at a dose rate of 0.4 mg/kg bodyweight. Five of nine helminth-free foals were treated on day 0, and the remaining four foals were used as controls. On days 0, 7, 14, 21 and 28 all nine foals were infected experimentally with 200,000 small strongyle larvae. Three treated and two control foals were necropsied on day 42 and the rest on day 43. Fourteen species of small or medium sized small strongyles were found in the control foals, 10 ...
Survey of anthelmintic resistance on Danish horse farms, using 5 different methods of calculating faecal egg count reduction. This study reports on the prevalence of anthelmintic resistance in strongyles of horses in Denmark. Of 5 methods used for the calculation of faecal egg count reduction (FECR) the method recommended by the World Association for the Advancement of Veterinary Parasitology, for the detection of resistance in sheep was the most sensitive procedure for detecting resistance. Using this method benzimidazole resistance was detected on 33 of 42 farms (79%) examined. Pyrantel was tested on 15 farms and FECR tests indicate resistance on 3 (30%) farms. On 2 farms on which resistance to pyrantel was detecte...
Efficacy of moxidectin and other anthelmintics against small strongyles in horses. To compare the efficacy of moxidectin to ivermectin, oxibendazole and morantel against some gastrointestinal nematodes in horses. Methods: Faecal egg count reduction after treatment. Methods: A farm was selected where the population of small strongyles in horses was known to be resistant to oxibendazole. Horses were allocated to treatment groups based on faecal egg counts. After treatment, faecal samples were taken up to 109 days after treatment and faecal egg counts estimated. Faecal cultures were used to estimate the contribution of small and large strongyles to the faecal egg counts at each...
Elimination of mucosal cyathostome larvae by five daily treatments with fenbendazole. The efficacy of five daily treatments with 7.5 mg fenbendazole/kg bodyweight against mucosal cyathostome larvae was evaluated in 20 12- and 24-month-old ponies with naturally acquired cyathostome infections. After three weeks communal grazing on infected pasture and six weeks indoors, one group of 10 ponies were treated. Six weeks later, both groups of ponies were humanely destroyed and their burdens of large intestinal cyathostome worms, including luminal parasites and mucosal larvae, were assessed. In the control animals approximately 7 per cent of the total worm burden was present in the gu...
Epidemiology of Anoplocephala perfoliata infection in foals on a stud farm in south-western Sweden. The egg output and humoral antibody response to scolex antigens of the equine tapeworm Anoplocephala perfoliata were monitored in naturally infected foals by an egg flotation/centrifugation method and an indirect enzyme-linked immunosorbent assay (ELISA). The study was performed on a stud farm in south-western Sweden between May 1994 and April 1995. Sequential blood and faecal samples were taken from 21 foals during their first summer on pasture and until tapeworm eggs were detected. Results were expressed separately for 10 and 11 foals born before and after the end of April 1994, respectively...
Efficacy of moxidectin 2% equine gel against natural nematode infections in ponies. The efficacy of moxidectin 2% oral gel (Equest, Fort-Dodge) against European worm strains was studied through post-mortem worm counts and feacal egg counts (FECs) in 12 young ponies naturally infected. The animals were allocated in two groups of six ponies each: the first one was treated at 0.4 mg/kg b.w. and the second one received a placebo and served as control. All the ponies were necropsied 14 days post-treatment. The efficacy of moxidectin in reducing strongyle FECs ranged from 99.8% to 100% from 3 to 14 days after treatment. Moxidectin efficacy was 100% against Trichostrongylus axei and...
The reappearance of strongyle eggs in the faeces of horses after treatment with moxidectin. The reappearance of strongyle eggs in the faeces of horses treated with moxidectin (0.4 mg/kg of body weight) was compared with that in the faeces of horses treated with ivermectin (0.2 mg/kg of body weight). The study was performed from December 1995 till June 1996. Horses were infected naturally in the preceding grazing period. Two groups of 24 horses each were treated with moxidectin and ivermectin respectively at week 0. No side effects were seen after treatment. Horses were housed from week -1 till week 17. From week 17 onwards the horses were on pasture. Faecal samples were taken from ea...
Comparative studies of ivermectin and moxidectin in the control of naturally acquired cyathostome infections in horses. The control of naturally acquired cyathostome infections in horses by treatments with ivermectin and moxidectin was evaluated in three field studies. In a first study the efficacy of both drugs was assessed in a faecal egg count reduction test. Both ivermectin and moxidectin demonstrated efficacies greater than 99 per cent for up to 60 days after treatment. In a second study, the period required for strongyle eggs to reappear was estimated in horses treated either with ivermectin or moxidectin. For the horses treated with ivermectin the period varied between 10 and approximately 13 weeks, and ...
[Endoparasitic fauna and incidence of species in yearling and adult horses in Upper Bavarian breeding farms with regular anthelmintic prophylaxis lasting for many years]. In this epidemiological study 127 horses from five breeding farms in Upper Bavaria were included. The horses were coproscopically examined in intervals of four weeks over a 16-month period. Since 1992 in all farms regular prophylactic treatments with anthelmintics have been carried out. In 127 horses at least five species were established, such as Parascaris equorum, Anoplocephala perfoliata, Gasterophilus intestinalis and small strongyles, whose third stage larvae were characterized by eight or twelve intestinal cells. Infections with small strongyles occurred most frequently, followed by G. ...
[Endoparasites of donkeys and horses kept in communal housing in Upper Bavaria; species spectrum and incidence]. In this epidemiological study of endoparasites 37 donkeys and 23 horses were included, which were examined coproscopically in regular intervals over a 15 month period. The animals derived from ten farms, in which regular prophylactic treatments with anthelmintics had been practiced at least for two years before this investigation. This study revealed the presence of at least twelve parasite species in donkeys, Eimeria leuckarti, Gasterophilus intestinalis, Fasciola hepatica, Anoplocephala perfoliata, Strongyloides westeri, Parascaris equorum, Dictyocaulus arnfieldi, Trichostrongylus axei and s...
Comparison of the reappearance of strongyle eggs on foals, yearlings and adult horses after treatment with ivermectin or pyrantel. The reappearance of strongyle eggs in faeces after treatment with ivermectin or pyrantel embonate was investigated in 22 foals, 36 yearlings, and 45 adult horses on five Dutch horse farms. The results confirmed earlier studies which showed an egg reappearance period of 9 and 6 weeks after ivermectin and pyrantel treatment, respectively. There were no differences between the egg reappearance periods of foals, yearlings, and adult horses. The mean egg counts of the yearlings were, however, consistently higher than the mean egg counts of the adult horses and foals in both ivermectin- and pyrantel...
[Spectrum of species and incidence of endoparasites in foals and their mother mares from breeding farms with and without anthelmintic prophylaxis in upper Bavaria]. In this epidemiological study 37 foals and mares were included, which have been coproscopically examined in regular intervals over a period lasting up to 13 months. The animals derived from nine breeding farms. In three of these farms no anthelmintics were used before this investigation, whereas in six farms at least three years before regular prophylactic treatments with anthelmintics have been carried out. This investigation revealed no differences in the species spectrum of endoparasites as well as in the incidence of infections as regards to the breeding farms with and without anthelmintic...
[Occurrence of Parascaris equorum in foals and adult horses under different breeding conditions]. Autopsies and analyses of faecal samples from working horses have shown common occurrence of ascarids in foals, whereas 19.6% of adult horses have been found infected. No influence of season on EPG in adult horses has been found. Study based on faecal samples from stud horses has shown that 5-6-month old animals were most susceptible to the infection. 50% of foals have been found infected in spite of deworming with the use of bezimidazole compounds. It has been stated that the proper dose of an anthelminthic is a basic problem in the control of ascarids.
Dose titration of moxidectin oral gel against migrating Strongylus vulgaris and Parascaris equorum larvae in pony foals. Moxidectin was tested for efficacy in ponies against experimental infections of 56 day Strongylus vulgaris larvae and 11 day Parascaris equorum larvae. Three dosages of moxidectin were tested: 300 micrograms per kg live body weight, 400 micrograms per kg, and 500 micrograms per kg, and the vehicle served as control. Ponies were first infected with 600 S. vulgaris third-stage larvae (L3) on Experiment Day 0 and then with 3000 embryonated P. equorum eggs on Day 45. Moxidectin treatments were administered on Day 56 and necropsy examinations were performed on Day 91. Strongylus vulgaris fourth-sta...
Dose titration of moxidectin oral gel against gastrointestinal parasites of ponies. Moxidectin was tested as an oral gel formulation during a controlled test performed to evaluate dosages against equine gastrointestinal parasites. Four groups of ten ponies were used. Ponies ranged from 1 to 20 years of age and were naturally infected in southern Louisiana or Mississippi. Fecal exams and fecal cultures were performed on all ponies to determine the strongyle egg counts and the percent distributions of large and small strongyles. Following these determinations, ponies were allocated to replicates of four ponies to provide an even distribution of strongyle infection, age, weight ...
The reappearance of strongyle eggs in faeces of horses treated with pyrantel embonate. The reappearance of strongyle eggs in the faeces of horses treated with pyrantel embonate was studied. The horses (103) were divided in 11 groups on 8 different farms. The efficacy of pyrantel embonate against strongyles, based on egg count reduction tests, was 99.8%. Mean weekly egg counts performed between week 2 and week 9 after treatment showed that 5 weeks after treatment the egg output passed the 90% reduction level. It is concluded that strategic treatments of horses with pyrantel embonate for the prevention of strongylosis should be administered with intervals of 6 weeks.
Epidemiological risk factors associated with a diagnosis of clinical cyathostomiasis in the horse. Multiple logistic regression was used to assess epidemiological risk factors associated with the diagnosis of cyathostomiasis in 87 cases of chronic diarrhoea in the horse. Age, season and the period since last receiving anthelmintics were identified as important risk factors using chi-square and two-sample t test analyses, whereas access to grazing, shared grazing with other horses and recurrence of signs were only weakly associated with a diagnosis of cyathostomiasis. Multivariate analysis of the parameters using logistic regression was performed. The final model included age, season and tim...
[Incidence of Parascaris equorum in foals and their mares after strategic use of wide-spectrum anthelmintics for several years]. In this epidemiological survey 30 foals and their mares from seven breeding farms were investigated. Six farms used wide spectrum anthelmintics strategically at least for three years, on one farm no anthelmintic prophylaxis was practiced. Excretion of P.-equorum-eggs occurred in all breeding farms and in 80% of the foals, but in only one mare. In foals infection with roundworms was detected at the earliest 85 days post partum. Before first shedding of P.-equorum-eggs wide spectrum anthelmintics had been administered to two and to one foal(s) one and two times, respectively, to four animals thr...
[Inquiry of veterinarians in Niedersachsen concerning the occurrence of parasitic diseases and their control in large animals]. In Lower Saxony approximately 3500 veterinarians were asked to fill in a questionnaire focused on the prevalence of parasitic infections in cattle, sheep, pigs, and horses, the preferred control measures and the antiparasitic drugs in use. Although the disappointing low number of only 48 veterinarians that participated in this survey prevented any representative conclusions the following trends were remarkable: gastrointestinal strongyles were the most prevalent parasites in cattle (34.8%), sheep (28.0%), and horses (42.3%). In pigs, ascarids were most often diagnosed (41.9%) followed by the s...
A field survey on anthelmintic resistance in equine small strongyles in Norway. A field survey at 17 stables involving 221 horses was performed to evaluate the presence of anthelmintic resistance in the equine small strongyles (cyathostomes). The horses were allocated into treatment groups, and resistance to fenbendazole (FBZ), pyrantel pamoate (PYR) and ivermectin (IVM) was tested by the faecal egg count reduction test (FECR-test). Faecal samples were collected at the time of treatment, 14 days post treatment and 90 days post treatment. Resistance to FBZ, which was defined as a faecal egg count reduction < 95%, was found in 14 out of 17 stables. In 2 of the 14 stables...
The prevalence and epidemiology of Anoplocephala perfoliata infection in Norway. The caecum and the adjacent 30 cm lengths of ileum and large colon of 201 horses from two different regions of Norway (Ostlandet and Trøndelag) were examined for the presence of Anoplocephala perfoliata. In all, 20% of the horses were infested with the cestode (27% in Ostlandet and 7% in Trøndelag). The mean number of worms in infected horses from the two regions was 18 and 6, respectively. Information was obtained on the age, sex, breed, type of pasture and anthelmintic treatment after the grazing season for 183 of the 20 horses. The degree of infestation with A. perfoliata was not influenc...
Outbreak of larval cyathostomiasis among a group of yearling and two-year-old horses. Larval cyathostomiasis was diagnosed as the cause of an outbreak of illness in a group of five young horses. One had the typical clinical signs of larval cyathostomiasis--sudden onset diarrhoea, weight loss, ventral abdominal oedema and pyrexia, but the other four suddenly started to lose weight rapidly and had limb and ventral abdominal oedema and pyrexia, in the absence of diarrhoea. Large numbers of cyathostome larvae were found in the faeces. Four of the five horses recovered after being treated with anthelmintics and steroids.
Comparison of daily and monthly pyrantel treatment in yearling thoroughbreds and the protective effect of strategic medication of mares on their foals. Studies on a Thoroughbred breeding farm in Ohio were done to: (1) compare the effects of daily administration of pyrantel tartrate feed pellets with monthly administration of a pyrantel pamoate paste to yearling horses (21 January-3 September); (2) assess the effects of daily pyrantel tartrate given strategically in spring/summer to foaling mares (1 April-16 August) and given for a prolonged period to barren mares (21 January-3 September); (3) determine if strategic medication of foaling mares with daily pyrantel tartrate protected their foals until weaning. There were no differences in cyatho...
