Topic:Benzimidazoles
Benzimidazoles are a class of anthelmintic compounds used to control parasitic infections in horses. These compounds are effective against a range of gastrointestinal nematodes by interfering with the parasites' energy metabolism. Common benzimidazoles used in equine medicine include fenbendazole, mebendazole, and oxibendazole. The efficacy of benzimidazoles can be influenced by factors such as dosage, administration frequency, and the presence of resistant parasite strains. Resistance to benzimidazoles is a growing concern in equine parasitology, necessitating ongoing research into resistance mechanisms and alternative control strategies. This page compiles peer-reviewed research studies and scholarly articles that explore the pharmacodynamics, resistance patterns, and clinical applications of benzimidazoles in horse health management.
Critical tests and clinical trials on oxibendazole in horses with special reference to removal of Parascaris equorum. The efficacy of oxibendazole given at dose level of 10 mg/kg of body weight was determined by 10 critical tests in foals and by 2 clinical trials in 20 foals (16 treated, 4 nontreated), with special interest in the drug activity against Parascaris equorum. The drug was uniformly efficacious (100%) against P equorum in the 10 critical-test foals, each having between 22 and 236 ascarids. Posttreatment reductions of ascarid egg counts in fecal samples were also 100% in suckling foals treated with oxibendazole given as a drench. Ascarid eggs did not reappear in fecal samples until the 8th week aft...
Benzimidazole resistance of equine stronygles–critical tests of six compounds against population B. Critical tests were conducted on eight horses naturally infected with several species of large and small strongyles from population B. Tested were six benzimidazoles, including thiabendazole (2 lots) (44 mg/kg of body weight); mebendazole (8.8 mg/kg); cambendazole (two formulations) (20 mg/kg); fenbendazole (10 mg/kg); oxibendazole (10 mg/kg); and oxfendazole (10 mg/kg). All compounds were administered by stomach tube except one of the two cambendazole formulations which was an intraoral paste. Removal of large strongyles (when present), Strongylus vulgaris and Strongylus edentatus, was 100% b...
Critical anthelmintic trials in ponies with oxfendazole and caviphos and concomitant studies on the spontaneous elimination of small strongylids. The efficacy of the benzimidazole, oxfendazole, and the organophosphate, caviphos, against gastrointestinal parasites of ponies was evaluated by the critcial test method. Oxfendazole (10 mg/kg of body weight) given in single oral doses was 100% effective against adult large strongylids (Strongylus vulgaris, Strongylus edentatus, and Strongylus equinus), 99% effective against adult small strongylids, and 97% effective against 4th-stage small strongylids (genera identified in order of frequency: Cylicostephanus, Cyathostomum, Cylicocyclus, Triodontophorus, Poteriostomum, Oesophagodontus, Cylicod...
Radioimmunoassay of oxfendazole in bovine, equine, or canine plasma or serum. A simple radioimmunoassay was developed for the determination of oxfendazole in plasma. Oxfendazole N-1(3)-valerate was coupled to polylysine via a carbodiimide reaction, and antiserum was developed in rabbits after inoculation with oxfendazole--polylysine conjugate. The assay was developed so that oxfendazole could be measured directly in a 0.1-ml aliquot of diluted or undiluted plasma. With the developed procedure, 200 pg of oxfendazole/ml of plasma can be determined quantitatively. Cross-reactivity was determined for closely related compounds and metabolites. The method was used to determin...
Evaluation of cambendazole paste against nematodes in horses in a field trial. The anthelmintic canbendazole (CBZ), adminis-
tered in several formulations to horses in critical
trials, has been shown to have high effcacy
against intestinal nematodes (3, 4, 6). There are
two reports of field trials with CBZ (2, 5), and
although a large number of horses were involved,
the efficacies reported were for a restricted
number of nematodes. Recently, CBZ paste was
administered to horses in another field trial and
the findings on rxdatability, safety and efficacy
against a wide range of nematodes are presented.
Critical anthelmintic trials in ponies with four benzimidazoles: mebendazole, cambendazole, fenbendazole, and albendazole. The comparative efficacy of four benzimidazoles against gastrointestinal parasites of ponies was evaluated by the critical test method. Mebendazole (8.8 mg/kg), cambendazole (20 mg/kg), fenbendazole (5 mg/kg), and albendazole (2.5 and 5 mg/kg) given in single oral doses were highly effective against adult large strongylids (Strongylus vulgaris, S. endentatus, S. equinus) and adult small strongylids (genera identified in order of frequency: Cylicostephanus, Cylicocyclus, Cyathostomum, Triodontophorus, Poteriostomum, Oesophagodontus, Cylicodontophorus, Gyalocephalus, and Craterostomum). Limited ...
Observations on development of Strongyloides westeri in foals nursing dams treated with cambendazole or thiabendazole. In 1 experiment, a prepatent period of 8 or 9 days was recorded for Strongyloides westeri in 4 pony foals raised worm-free but infected with parasitic 3rd stage larvae in the postpartum milk of a mare via gastric intubation. This is about 2 to 6 days less than the usual age that eggs of S westeri appear in the feces of naturally infected suckling foals, in central Kentucky.
In other studies, mares were treated with cambendazole or thiabendazole at 0 to 2 days after parturition and continued for 7 to 16 days. Appearance of S westeri eggs in feces of foals nursing treated mares was prevented ...
Critical tests of the antiparasitic activity of thiabendazole and trichlorfon sequentially administered to horses via stomach tube. Thirteen critical tests were conducted in horses naturally infected with helminths and bots. Single doses of thiabendazole (44 mg/kg of body weight) and trichlorfon (40 mg/kg of body weight) powder formulations were administered as suspensions sequentially given via stomach tube to evaluate the efficacy of the combination against the large parasites of horses. Parasite removal efficacies were 100% against 2nd instar Gasterophilus intestinalis and 2nd and 3rd instar Gasterophilus nasalis and 82 to 100% against 3rd instar G intestinals. There were complete removals of mature and immature Parasca...
Reproductive function in stallions treated with cambendazole. Twenty stallions were used to determine if the anthelmintic cambendazole affected seminal characteristics, spermatogenesis, concentration of testosterone in blood serum, or weights of the reproductive orgrans. With minor exceptions, significant differences were not found between values for 10 control and 10 stallions treated with a single oral dose (40 mg/kg body weight) of cambendazole. The treatment did not affect reproductive function and it was concluded that the drug should have no effect on the fertility of stallions.
Strongyle infections in ponies. I. Response to intermittent thiabendazole treatments. A group of seven ponies naturally infected with large numbers of small strongyles and raised under conditions to minimize reinfection were treated periodically over a three year span with thiabendazole at the rate of 44 mg/kg body weight. Based on the absence of worm eggs in the feces following each treatment, thiabendazole removed the adult strongyles present with a new population subsequently developing by maturation of inhibited larvae. It took as many as four or five treatments to eliminate or reduce significantly the worm burdens present in the ponies under the conditions of this study. S...
[Concerning the toxicity of parbendazole (Helmatac 30) to horses and ponies (author’s transl)]. The toxicity of parbendazole in different doses was investigated with 52 horses and 16 ponies, in twelve groups. Side effects observed with the anthelmintic were laxation (soft dung, diarrhoea), anorexia, and listlessness. The seriousness of these symptoms depended greatly on the dose used. Half the therapeutic dose of parbendazole (2.5 to 3.75 mg/kg) administered on two consecutive days led, as a rule, to only slight toxic symptoms and proved highly effective with regard to gastro-intestinal nematodes occurring in horses and ponies. The utilisation of "standard powders" (not commercially avai...
Efficacy studies with three formulations of cambendazole in horses. Treatment with 3 formulations of cambendazole (paste, pellets, and suspension) was compared with thiabendazole treatment in 181 Quarter Horses (females and intact and altered males) of different ages in 2 experiments. The mean output of strongyle eggs, as measured by eggs per gram of feces (epg), was reduced by at least 95% by the 3 formulations of cambendazole compared with pretreatment epg and epg in simultaneously nonmedicated horses. Eggs of Parascaris equorum were seen in 19 of the younger horses in experiment I. Parascaris eggs were not seen in postmedication fecal samples from 14 horses...
Suppression of the pathogenic effects of Strongylus edentatus larvae with thiabendazole. Four pony foals were inoculated with Strongylus edentatus infective larvae and on days 3 and 4 postinfection two of the ponies were treated with thiabendazole, each at the rate of 440 mg/kg of body weight. Total circulating eosinophil counts in untreated ponies increased to over 1700 per cu mm after the second week postinfection. In the treated ponies as well as in an uninfected untreated pony eosinophil counts did not increase beyond 100 per cu mm. At necropsy on day 35 postinfection the cecum, colon and omentum of treated ponies were normal and few tracks were present on the surface of the l...
Critical tests of suspension, paste, and pellet formulations of cambendazole in the horse. Three formulations of cambendazole were evaluated for anthelmintic activity by critical testing method in 21 horses. Cambendazole suspension was administered via stomach tube at the dose rate of 10 mg/kg to 3 horses and at the dose rate of 20 mg/kg to 3 horses. Cambendazole paste was given intraorally to 8 horses, and the pellet formulation was fed to 7 horses at the dose rate of 20 mg/kg. Anthelmintic activity of cambendazole was similar for all dose rates and formulations. Gasterophilus intestinalis, Gasterophilus nasalis, Draschia megastoma, Anoplocephala perfoliata, and Anoplocephala magna...