Efficacy of epsiprantel against Echinococcus granulosus infections in dogs

Dogs with 41-day-old experimental infections of Echinococcus granulosus were treated orally with epsiprantel. Single doses of 2.5 mg kg-1, 5.0 mg kg-1 or 7.5 mg kg-1 were effective in removing more than 99 per cent of these parasites, but total clearances of worms only occurred in dogs given the highest dose.     

Efficacy of paraherquamide against immature Trichostrongylus colubriformis in the gerbil (Meriones unguiculatus)

Paraherquamide was 98 to 100 per cent effective against six-day-old Trichostrongylus colubriformis infections in gerbils when given as single oral doses of 1.56 mg kg-1 and above. Doses of 0.78 or 0.39 mg kg-1 were 96 and 66 per cent effective, respectively. A single oral dose of 200 mg kg-1 was well tolerated.     

Laboratory investigations in sheep with a new anthelmintic.

The efficacy of fenbendazole against the following gastrointestinal nematodes was tested in experimentally infected lambs: O circumcincta, H contortus, T colubriformis and N filicollis. As low a dose as 0.5 mg per kg reduced the egg output of a patent infection with H contortus and T colubriformis by 85 per cent to 100 per cent. A dose of 3.5 mg per kg has a 100 per cent effect on three or 10-day-old stages of H contortus and one of more than 99 per cent or 100 per cent T colubriformis. The same dose reduces seven-day-old stages of O circumcincta and N filicollis by more than 94 per cent or 100 per cent, while 10 mg per kg produces a 100 per cent elimination of seven-day-old stages of O circumcincta. In field trials and efficacy of more than 99 per cent was determined after oral dosage with 5.0 mg per kg against Ostertagia, Haemonchus, Trichostrongylus, Cooperia, Nematodirus and Chabertia. Fenbendazole has a wide therapeutic-toxic dose ratio. Discoloration of the wool does not occur. Fenbendazole can be administered as a drench or with the feed.     

Evaluation of oxfendazole against natural infections of gastro-intestinal nematodes and lung-worms in calves.

The anthelmintic activity of oxfendazole (Syntex) was tested in calves at dosages of 2-5 and 5-0 mg per kg. At both dose levels, oxfendazole showed 100 per cent efficacy against adult Ostertagia ostertagi, O lyrata, O cremensis, fifth stage Ostertagia spp and adult Haemonchus spp. Against adult Cooperia oncophora, efficacy was 99.8 per cent and 100 per cent at doses of 2.5 mg per kg and 5.0 mg per kg respectively while at both dose levels 100 per cent activity was recorded against C surnabada and fourth and fifth stage Cooperia spp. One hundred per cent efficacy was obtained with both dose levels against adult and fifth stage Dictyodaulus viviaprus; against Trichuris spp, percentage efficacy was 92 and 100 per cent at doses 2.5 and 5.0 mg per kg respectively. Oxfendazole showed higher efficacy than levamisole against Ostertagia spp but against the other species encountered, both anthelmintics possessed similar efficacy. Both anthelmintics significantly increased the calves' weight gains.     

The efficacy of fenbendazole and albendazole against immature and adult stages of benzimidazole-resistant sheep trichostrongylids

The efficacy of two recently introduced benzimidazole anthelmintics, albendazole and fenbendazole, was determined for six-day, 10-day and adult stages of resistant strains of Haemonchus contortus and Trichostrongylus colubriformis. Albendazole, at 3.8 mg/kg reduced H contortus worm counts by 92.4, 70.8 and 67.1 per cent while fenbendazole, at 5.0 mg/kg, reduced worm burdens by 51.7, 95.5 and 93.4 per cent against six-, 10- and 25-day-old parasites respectively. For T colubriformis, the corresponding reductions with albendazole were 97.7, 95.8 and 64.9 per cent and for fenbendazole 29.0, 66.3 and 33.4 per cent. Compared with susceptible strains of H contortus and T colubriformis, for which therapeutic doses of benzimidazole anthelmintics are generally highly active against all stages of development, the present results show that these drugs do not have a uniform level of activity against all developmental stages of resistant strains.     

Laboratory investigations on pigs with the new anthelmintic fenbendazole.

The efficacy of fenbendazole was investigated in piglets infected artificially with Hyostrongylus rubidus and Oesophagostomum spp. After administration of 3.5 mg/kg, five-day-old stages of H rubidus were reduced by 72.5 per cent; an effect of 78.4 per cent, 96.0 per cent and 100 per cent was achieved against five-day-old, 16-day-old and 42-day-old stages, respectively, of H rubidus using a dose of 5 mg/kg. A 55 per cent effect was obtained against five-day-old stages after the administration of 3.5 mg/kg. A dose of 5 mg/kg reduced five-day-old, 16-day-old and 42-day-old stages of Oesophagotomum spp by 72.6 per cent, 44 per cent and 100 per cent respectively.     

Anthelmintic efficacy of netobimin against naturally acquired gastrointestinal nematodes in yearling heifers

The efficacy of netobimin (Coded SCH 32481, Schering Corporation) in removing naturally acquired gastrointestinal nematode infections was evaluated in 10 treated and 10 untreated (control) yearling beef heifers. The anthelmintic was administered as an oral drench at a dose level of 7.5 mg kg-1 body weight. Fecal egg per gram (EPG) counts were reduced with netobimin by 98% (P less than or equal to 0.01) at both 1 and 2 weeks post-treatment (PT). The compound was highly effective in removing Oesophagostomum radiatum (100% at P less than or equal to 0.01), Cooperia spp. (97.66% at P less than or equal to 0.01) and Nematodirus helvetianus (100%, although not significant), but was ineffective against immature Ostertagia ostertagi (3.19%) and only moderately effective against adult forms (66.14% at P less than or equal to 0.05). The low efficacy against adult O. ostertagi was partially attributed to the maturation of fourth-stage larvae, not removed by the 7.5 mg kg-1 treatment, during the 14-day treatment-slaughter interval. Efficacy against Trichuris spp. could not be evaluated due to low levels and unequal numbers of worms recovered in the groups. The overall efficacy against adult species, excluding Trichuris spp., was 67.40% (P less than or equal to 0.05). No adverse reactions or signs of toxicosis were observed in heifers treated with netobimin.     

Protection developed against reinfection by Dictyocaulus viviparus following anthelmintic treatment of a one-day-old primary infection in cattle

Single doses of 7.5 mg/kg levamisole subcutaneously and 5 mg/kg oxfendazole per os and three daily doses of diethylcarbamazine intramuscularly were 86.9, 82.1 and 46.6 per cent efficient, respectively, against one-day-old Dictyocaulus viviparus. These three dosage regimes were also associated, respectively, with 92.5, 36.4 and 56.0 per cent protection against reinfection following anthelmintic treatment. It is suggested that the high degree of protection following the use of levamisole may be a consequence of rapid and effective anthelmintic activity combined with immunomodulating effects.     

The anthelmintic efficacy of fenbendazole against a mixed nematode infection in sheep.

Fenbendazole (methyl-5-(phenylthio)-2-benzimidazole carbamate) at dose rates of 5 mg/kg and above was 100 per cent effective in eliminating a naturally acquired Dictyocaulus filaria infection in sheep. The drug was 100 per cent effective in eliminating concurrent infections of adult Trichostrongylus axei, Haemonchus contortus, Haemonchus placei, Ostertagia circumcincta, Ostertagia ostertagii, Cooperia oncophora, Cooperia mcmasterii, Nematodirus spathiger, Neumatodirus filcollis, Oesophagostomum venulosum and Chabertia ovina. Fenbendazole was 93 per cent and 97 per cent effective at doses of 5 and 10 mg/kg respectively in removing infection with adult T colubriformis, and post-treatment worm-egg production was completely suppressed in surviving female worms. No adverse side-effects were observed in treated sheep at either of the two dose rates used.     

Evaluation of a beef-based chewable formulation of pyrantel pamoate against induced and natural infections of hookworms and ascarids in dogs.

Pyrantel pamoate, formulated in a beef-based chewable tablet, was evaluated for efficacy in dogs against induced and natural infections of Toxocara canis, Toxascaris leonina, Ancylostoma caninum and Uncinaria stenocephala. Dose titration trials were conducted in Canada, the UK and Germany in dogs treated with pyrantel (as pamoate salt) at 0, 2.5, 5 or 10 mg kg-1 body weight. These studies showed that a dose rate of 2.5 mg kg-1, the efficacy of pyrantel against adult T. canis, T. leonina, U. stenocephala and A. caninum was 76.1, 85.6, 100 and 87.9%, respectively. Efficacy at 5 mg kg-1 against the same parasites was 94.2, 92.0, 93.5 and 93.8%, respectively, and at 10 mg kg-1 efficacy was 91.2, 97.6, 98.7 and 91.3%, respectively. No adverse effects due to treatment were seen in any of these trials.     

The anthelmintic efficacy of netobimin against experimental infections of Fasciola hepatica in sheep

Netobimin (coded SCH 32481, Schering Corporation), a new broad-spectrum anthelmintic having both fasciolicidal and nematocidal properties was evaluated for efficacy against mature Fasciola hepatica infections in sheep. The trial was conducted with 30 cross-bred spring lambs, each experimentally infected with 250 F. hepatica metacercariae. A single treatment of netobimin was administered at 17 weeks post-infection (PI) by oral drench at 7.5 or 20 mg kg-1 body weight while 10 animals remained as untreated controls. At necropsy (either 1 or 2 weeks post-treatment), the mean number of adult flukes recovered from the control, 7.5 and 20 mg kg-1 groups were 94.7, 35.9 and 8.8, respectively. The resulting efficacies were 62% (P less than or equal to 0.05) and 90.7% (P less than or equal to 0.01), respectively. No clinical signs of fascioliasis were noted in any sheep during the trial. No signs of toxicosis nor any adverse reactions to the drug were observed.     

Efficacy evaluation of epsiprantel (Cestex) against Echinococcus mutilocularis in dogs and cats

Helminth-free dogs and cats were experimentally infected with protoscoleces of Echinococcus multilocularis and used in controlled trials for efficacy evaluation of the cestodicide epsiprantel. In two separate trials each 4 dogs were treated at day 20 post infection (p.i.) with average oral dosages of 5.1 (4.9-5.3) and 5.4 (5.2-5.8) mg/kg body weight (b.w.) epsiprantel, respectively, and necropsied at day 24 p.i. Among each 4 dogs of the two untreated control groups all animals were infected and had high intestinal worm burdens with averages of 33.575 and 100.725 E. multilocularis specimens per animal (individual worm burdens in group Ib 59,500-149,800, group IIb 20,500-43,200); in the two groups of treated dogs the average worm burdens were reduced by 99.6 and 99.9%. Among 8 treated dogs 4 were helminth-free, the other 4 had residual worm burdens (10-70 in 3 dogs, 1480 in 1 dog). In each 5 cats single oral treatments with average doses of 2.7 (2.7-2.8) and 5.5 (5.5-5.5) mg/kg b.w. epsiprantel were 100% effective against E. multilocularis 20 days p.i. and eliminated the worm burdens from all 10 animals. In the untreated group of 5 cats the average worm burden was 2864 per animal (individual worm burdens 20-6830). Side effects of the drug treatment were not observed. The results of the study show that in single therapeutic dosages recommended by the producer (dogs 5.5 mg, cats 2.75 mg/kg b.w.) epsiprantel eliminates E. multilocularis to over 99% or completely, but residual worm burdens may persist in some animals.     

The effects of single and multiple doses of thiabendazole on growing and arrested stages of the rabbit stomach worm Obeliscoides cuniculi

Preliminary observations, using 5 rabbits carrying long-standing infections, indicated that single doses of thiabendazole were effective against adult O. cuniculi and that repeated doses may have had some effect on arrested larvae. A multiple dosing regime, consisting of 1 dose at 110 mg kg-1 body weight followed by 8 doses at 70 mg kg-1 body weight at 4-h intervals, was successful in removing 99.12% of developing worms and 86.04% of arrested larvae.     

Use of sentinel lambs for early monitoring of the South Powys Hydatidosis Control Scheme: prevalence of Echinococcus granulosus and some other helminths.

Sentinel lambs were used to identify young Echinococcus granulosus infections in sheep, to provide an early indication of the progress of the South Powys Hydatidosis Control Scheme. Four sentinel lambs were purchased on each of 60 farms, from inside and outside the control area; they were examined when approximately six, 10 and 15 months of age. Gross examination, thin slicing of organs and histological examination of the lesions in the viscera revealed no E granulosus hydatid cysts in lambs born within the control area, whereas 25 per cent of the 15-month-old lambs from outside the area harboured E granulosus cysts (less than 1 to 2 mm in diameter). Lambs from E granulosus infected farms had significantly higher anti-E granulosus ELISA antibody titres than lambs from uninfected farms. It was concluded that within one year of beginning to treat dogs with praziquantel every six weeks the transmission of E granulosus to sheep had ceased. In contrast, this treatment did not prevent infections with Taenia hydatigena or T ovis; an examination of the 240 lambs revealed T hydatigena in 33.3 per cent of them, Tovis in 4.2 per cent, Dictyocaulus filaria in 12.1 per cent and Meullerius capillaris in 49.2 per cent.     

Efficacy, safety and palatability of a new broad-spectrum anthelmintic formulation in dogs

The efficacy, safety and palatability of a new flavoured chewable anthelmintic tablet were investigated in dogs. The efficacy, based on worm counts, of a single recommended therapeutic dose (RTD) of 5 mg pyrantel + 20 mg oxantel + 5 mg praziquantel/kg bodyweight was assessed in experimental infections (EI) and natural infections (NI) with Trichuris vulpis, Echinococcus granulosus and Toxocara canis. For T vulpis, the efficacy of the treatment was 99.3 per cent in EI (comparing groups of six treated and six control dogs) and 100 per cent in NI (nine treated and nine control dogs). For E granulosus, the efficacy was more than 99.9 per cent in EI (11 treated and 11 control dogs). For T canis, the efficacy was 94.3 per cent in EI (10 treated and 10 control dogs) and 100 per cent in NI (12 treated and 13 control dogs). In a field study, Ancylostoma caninum (11 dogs) and T canis (11 dogs) faecal egg counts were reduced by more than 99 per cent, and in eight dogs with Dipylidium caninum proglotides in the faeces the efficacy was 100 per cent. The tablets were readily consumed by 56 of 64 (87.5 per cent) privately owned dogs. Safety was assessed in groups of six dogs treated either once with twice the RTD, once with six times the RTD, with twice the RTD on three consecutive days, or untreated. There were no significant differences in blood parameters between the groups, and no abnormal clinical findings. Two dogs treated with six times the RTD vomited, but no vomiting was observed when administration was repeated two days later.     

Anthelmintic efficacy of febantel paste in naturally infected calves

The purpose of the present study was to verify results of the lowest dose (5 mg kg-1) of febantel evaluated in an earlier trial in which there were no differences in efficacies of three dose rates (5, 7.5 and 10 mg kg-1 body weight) against natural gastrointestinal nematode infections of cattle. Fourteen Angus calves (mean weight and age of 155 kg and 525 days, respectively), from the same farm, with relatively heavy (mean of 448 eggs g-1 feces (epg] parasite burdens were selected. After an adjustment period of 8 days in drylot, beginning on 25 July, seven calves were treated with a 45.5% paste formulation of febantel. On Day 7 post-treatment, calves were necropsied for determination of residual worms. Rectal fecal samples were obtained prior to adjustment, at treatment, 5 days post-treatment and at necropsy. On both Day 5 post-treatment and at necropsy a mean of less than 1 epg was recovered from treated calves compared with 765 and 1566 epg, respectively, in control calves. Worms counts at necropsy revealed an efficacy of 98.5% against all adult abomasal worms (Haemonchus placei, 100%, P less than 0.02; Trichostrongylus axei, 99.4%, P less than 0.0001; Ostertagia ostertagi, 90.5%, P less than 0.0002). Treatment was 100% efficacious against adult small and large intestinal worms. However, numbers of Bunostomum phlebotomum, O. radiatum and Trichuris spp. recovered in the control calves were too low to enable a reliable test of drug efficacy. Treatment was not effective against either mucosal or luminal fourth stage larvae of abomasal O. ostertagi.(ABSTRACT TRUNCATED AT 250 WORDS)     

Efficacy of a fenbendazole-triclabendazole combination against Fasciola hepatica and gastrointestinal nematodes in sheep

A fenbendazole and triclabendazole combination was tested against experimentally induced 6-and 14-week-old infections of Fasciola hepatica and naturally acquired infections of gastrointestinal nematodes in sheep. Forty-eight sheep were divided randomly into six treatment groups of eight animals each. At 7.5 and 10.0 mg kg-1 body weight (BW) (3.75 and 5.0 mg kg-1 BW of each drug), the drug combination was 98.3 and 99.7% effective against 6-week-old F. hepatica infections, and 100 and 99.9% effective against 14-week-old infections. At the same drug dosages, the drug combination was effective against naturally acquired adult Ostertagia spp. (97.3-100%) and adult Nematodirus spp. (90.3-99.9%). No adverse effects associated with treatment were noted.     

Effects of cimetidine and ranitidine on basal gastric pH, free and total acid contents in horses

The basal gastric pH, free and total acid contents from five adult horses were determined at two-hour intervals for six- to eight-hour periods. The basal gastric pH, free and total acid contents varied from 2.14 +/- 0.08 to 2.41 +/- 0.14, 28.63 +/- 8.27 to 17.89 +/- 2.86 mmol litre-1 and 41.38 +/- 9.72 to 37.38 +/- 3.70 mmol litre-1, respectively. Cimetidine (8.8 mg kg-1 orally) and ranitidine (2.2 mg kg-1 orally) increased the basal gastric pH to above 3.6 (P less than 0.05) with a concomitant reduction of 75 per cent and 75 to 100 per cent in the basal gastric free acid content, respectively, for an eight-hour period. Cimetidine (4.4 mg kg-1, intramuscularly) and ranitidine (1.4 mg kg-1, intramuscularly) increased the basal gastric pH to above 3.6 with a concomitant reduction of 54 to 93 per cent and 69 to 100 per cent in the basal gastric free acid content, respectively, for an eight-hour period. This study shows that the horse is a basal acid secretor, and that cimetidine and ranitidine, two widely used histaminergic-H2 type antagonists in human clinical practice are effective in horses with ranitidine being approximately four times more potent than cimetidine.     

The efficacy of netobimin against a benzimidazole susceptible and a resistant strain of Haemonchus contortus in sheep in The Netherlands

Netobimin was tested for efficacy against Haemonchus contortus using 7 groups of 5 parasite-free lambs of six months age. The lambs in group 1 and 2 were infected with 10,000 larvae of a benzimidazole susceptible strain and those in groups 3-7 with the same dose of a resistant strain. The following treatment scheme was applied 21 days after infection: lambs in groups 2 and 4-7.5 mg kg-1 netobimin, in group 5-20 mg kg-1 netobimin, in group 6-5 mg kg-1 oxfendazole and in group 7--3.8 mg kg-1 albendazole. The lambs in groups 1 and 3 remained untreated. All lambs were slaughtered 28 days after infection. Egg counts decreased in all lambs after treatment, but increased again in lambs in groups 4, 6 and 7. There was a slight increase in lambs in group 5, while those in group 2 remained negative. Post-mortem worm counts showed a reduction of 99.8 per cent in lambs in group 2 compared to those in group 1. In lambs in group 4-7 the reduction of worm counts was respectively 40.9, 89.5, 24.7 and 40.7 per cent compared to those in group 3. Egg development assays carried out 20 days after infection showed an average LD50 of 0.46 mg ml-1 thiabendazole for the resistant strain. After treatment (day 27) the LD50 was 0.53, 0.48, 0.58, 0.56 and 0.47 in lambs in the groups 3-7. It is concluded that netobimin and other (pro)-benzimidazoles should not be used in cases of benzimidazole resistance and that levamisole, pyrantel tartrate or ivermectin are preferable.     

Bromsulphthalein and indocyanine green elimination from plasma, and urinary bromsulphthalein excretion, in normal cats

The elimination of bromsulphthalein (BSP) and indocyanine green (ICG) from plasma and urinary excretion of BSP were investigated in healthy cats. At 5 mg kg-1, BSP elimination fitted a two-compartment open model, with mean t1/2 beta of 7.1 (SD 2.5) minutes. A tendency for slower elimination of BSP at 10 mg kg-1 suggested saturation of excretory mechanisms, while at 2 mg kg-1 accurate dosing and assay of low BSP concentrations were difficult. Urinary recovery of BSP at 5 mg kg-1 was 0.01 to 0.13 per cent of the total dose. Plasma ICG (0.5 mg kg-1) data fitted a one-compartment open model, with mean t1/2 2.7 (SD 1.0) minutes. In cats, retention tests are more attractive than clearance tests because fewer blood collections are necessary. Proposed reference values are under 3.6 per cent retention of BSP (5 mg kg-1) at 30 minutes and under 17.5 per cent retention of ICG (0.5 mg kg-1) at 15 minutes. At present economic and technical factors favour BSP over ICG.