Anthelmintic efficacy of albendazole in cattle: comparison of critical and controlled tests.

Twelve calves were experimentally inoculated with 6 species of gastrointestinal nematodes and the liver fluke, Fasciola hepatica. Six calves were administered albendazole at 10 mg/kg of body weight, and the drug efficacy was determined by critical and controlled tests. Albendazole was only 74% effective against Haemonchus contortus (cambendazole-resistant strain), 99 to 100% effective against Ostertagia ostertagi, Trichostrongylus colubriformis, Cooperia oncophora, and Oesophagostomum radiatum, and 54% effective against the liver fluke. Except for H contortus, the critical test provided as accurate a measurement of drug activity against gastrointestinal nematodes as the controlled test provided.     

Efficacy of ivermectin against the abomasal nematode mecistocirrus digitatus in naturally infected zebu calves

Anthelmintic efficacy of ivermectin against Mecistocirrus digitatus was evaluated in 10 naturally infected zebu calves. Group 1 (n = 5) was not treated, and group 2 (n = 5) was treated SC with 200 micrograms of ivermectin/kg of body weight. Calves were euthanatized 14 or 15 days after treatment. There was 100% overall reduction of M digitatus in treated calves, which was significant (P = 0.0079) compared with reduction in controls. Cooperia punctata, Haemonchus similis, and Trichostrongylus axei were found in controls. Efficacy against these parasites in treated calves was 100%.     

Resistance of Cooperia to ivermectin treatments in grazing cattle of the Humid Pampa, Argentina

A field experiment and a controlled efficacy trial were conducted to demonstrate resistance of cattle trichostrongylid nematodes to endectocidal compounds in grazing cattle on the Humid Pampa, Argentina. Male Polled Hereford calves, aged 9-11 months old, with a history of frequent treatments with compounds of the avermectin/milbemycin class, were used for the trial. The field experiment involved six groups of 10 animals each, which were subcutaneously treated with either ivermectin (IVM), long-acting ivermectin (LA-IVM), moxidectin (MXD) or doramectin (DRM) at a dosage of 0.2mg/kg BW. A fifth group was treated orally with fenbendazole at a dosage of 5mg/kg BW; the sixth group of calves served as non-treated control. Faecal samples were collected from each animal on the day of treatment and at 14 days after treatment. Nematode egg counts were performed to estimate the faecal egg count reduction test (FECRT). The FECRT showed that reductions were 65% (IVM), -20% (LA-IVM) and 85% (DRM). Egg counts from calves treated with MXD or fenbendazole were reduced by 95 and 100%, respectively. For the controlled efficacy trial, six animals with the highest egg counts from the IVM, LA-IVM and non-treated control groups, were necropsied on day 18 after treatment to determine numbers and nematode species in the abomasum and small intestine. The results indicated that efficacy against Cooperia oncophora was 62.7 and 48% for IVM and LA-IVM, respectively. Neither of the IVM formulations showed efficacy against Trichostrongylus spp. in the small intestine. However, the absence of Trichostrongylus spp. in some animals of both treated and control groups precluded a valid assessment of efficacy or resistance. It was concluded that resistance of trichostrongylid nematodes to the avermectin/milbemycin class of compounds in grazing cattle of the Humid Pampa, Argentina, may be strongly established on farms where cattle are treated at frequent intervals throughout the year.     

Efficacy of concomitant early summer treatment with fenbendazole and clorsulon against Fasciola hepatica and gastrointestinal nematodes in calves in Louisiana

The efficacy, safety, and compatibility of fenbendazole (FBZ) and clorsulon (CLN) were tested after oral administration of label recommended and of higher (5x) dosage rates to calves naturally infected with gastrointestinal nematodes and Fasciola hepatica. Results for 42 calves allotted to 4 treatment groups indicated a similar efficacy against mature F hepatica by FBZ (5 mg/kg of body weight) and CLN (7 mg/kg) in a combined oral suspension, compared with CLN (7 mg/kg) alone (100 vs 99% reduction). A lesser efficacy was observed against immature flukes (88.6 and 84.9% reduction, respectively). Calves given 25 mg of FBZ/kg and 35 mg of CLN/kg had nearly complete reduction of both mature (99.6%) and immature flukes (99.1%). Fasciola egg counts were reduced by greater than 99.5% in all treated groups. Against Ostertagia ostertagi, the percentage of efficacy of the combined FBZ (5 mg/kg) and CLN (7 mg/kg) treatment was 94.3% against adults and 81.3% against inhibited larvae. Efficacy against all other nematodes was 100%, except against Cooperia spp adults (98.3%) and immature Oesaphagostomum radiatum (88.0%). At 5 x dosage rates for FBZ and CLN, percentage of removal of adults and inhibited larvae of O ostertagi was 99.3 and 99.0%, respectively, and 99 to 100% for other nematodes. Results indicate that FBZ and CLN are compatible when mixed together and administered as an oral suspension to cattle and that the efficacy is similar to that of the drugs individually. On the basis of further results, we suggest that summer treatment may be superior in preventive value for gastrointestinal nematodes and F hepatica, compared with spring treatment, because of seasonal infection dynamics of the major cattle parasites in Louisiana.     

The efficacy of oxfendazole against natural infections of nematodes & cestodes in sheep

Oxfendazole (5 mg/kg) was tested against natural infections of nematodes and cestodes in sheep in three experiments.

It was 100% effective against all stages of Ostertagia sp., Nematodirus spathiger, Oesophagostomum venulosum, Chabertia ovina, Moniezia expansa, immature 5th stage and adult Cooperia curticei and 4th stage Trichostrongylus sp. Efficacy was 99%–100% against immature 5th stage and adult Trichostrongylus sp., 67.8%and 91.6% against adult Strongyloides sp., 80.7%and 89.5% against immature 5th stage Trichuris ovis and 74% and 79% against Trichuris ovis.     

Activity of ivermectin against natural infections by abomasal nematodes in lambs in controlled tests: evaluation of equine and bovine injectable formulations administered intraorally

The efficacy of 2 injectable formulations of ivermectin, administered intraorally at the dosage of 200 micrograms/kg of body weight, was evaluated against naturally occurring infections by abomasal nematodes in lambs in 2 controlled tests. One test (A) included 17 lambs treated with the equine formulation and 16 nontreated lambs. For the other test (B), 14 lambs were treated with the bovine formulation, and 12 were nontreated. In controlled test A, only mature nematodes were recovered, and removals were 98% to 100% for Haemonchus contortus, Ostertagia circumcincta male, O trifurcata male, Ostertagia spp female, and Trichostrongylus axei. For controlled test B, removals were 99% to 100% for Haemonchus spp (immature), H contortus (mature), Ostertagia spp (immature), O circumcincta male (mature), O trifurcata male (mature), Ostertagia spp female (mature), Trichostrongylus spp (immature), and T axei (mature). Toxicosis was not evident in treated lambs.     

Efficacy of ivermectin administered via sustained-release bolus against gastrointestinal nematodes in cattle

Twelve calves (mean weight, 175.5 kg) were used to confirm efficacy of ivermectin delivered from a prototype sustained-release bolus against naturally acquired gastrointestinal nematodes including early fourth-stage (inhibited) larvae of Ostertagia ostertagi. The calves were allocated by restricted randomization on weight to 1 of 2 groups: controls, to which a placebo bolus was given orally, and treated calves, to which a sustained-release bolus designed to deliver 8 mg of ivermectin/day at a steady rate was given orally. After treatment, the 2 groups were housed in separate pens with concrete flooring. Twenty-eight days after treatment, all calves were euthanatized and necropsied. The ivermectin-treated calves had no larval or adult Ostertagia spp and significantly (P less than 0.01) fewer adult Trichostrongylus axei and adult Cooperia (C oncophora, C punctata and C surnabada) than control calves. Efficacy of ivermectin was greater than 99% for Cooperia spp, and 100% for other parasites. Drug-related adverse reactions were not observed.     

Efficacy of abamectin against natural infections of gastrointestinal nematodes and lungworm of cattle with special emphasis on inhibited, early fourth stage larvae of Ostertagia ostertagi.

The anthelmintic efficacy of abamectin (avermectin B1) was evaluated against gastrointestinal nematodes, including Ostertagia ostertagi inhibited larvae and lungworm, in yearling crossbred beef heifers during late spring. The calves were grazed on contaminated pasture for 10 weeks and then held under conditions free of nematode infection for 3 weeks prior to allotment and treatment on 5 June. Thirteen calves were randomly assigned to two groups of six by restricted randomization on body weights; the extra lightest calf was assigned to the non-treated control group. Group 1 calves were treated with abamectin at 200 micrograms kg-1 body weight by s.c. injection and Group 2 calves were not treated; all were killed at 14 days after treatment. Ostertagia ostertagi was present in all controls; arithmetic mean numbers of adults, developing fourth stage larvae (L4) and inhibited EL4 were 7683, 605 and 36,102, respectively. Other nematode genera present in controls in sufficient numbers for the experiment were Haemonchus placei adults, Trichostrongylus axei adults, Cooperia spp. adults, Oesophagostomum radiatum adults, Bunostomum phlebotomum adults, Dictyocaulus viviparus adults and E5 (immature adults). Abamectin was highly effective (consistently greater than 99% efficacy and P less than 0.05) in removing all nematodes present in treated calves as represented in non-treated controls, including the primary target of Ostertagia ostertagi inhibited EL4. The lowest efficacy was 93.8%, against D. viviparus E5.     

Efficacy of avermectin B1a for treatment of experimentally induced nematode infections in cattle

Two formulations of avermectin B1a, C-076 and MK-933, were examined for anthelmintic activity in two trials, each using 20 calves with experimentally produced nematode infections. In one trial, C-076 was given orally, and in the other trial, MK-933 was given by injection at dosages of 50, 100, and 200 micrograms/kg of body weight. Treated calves were held for 7 to 8 days and then, together with nontreated controls, were euthanatized and were examined for nematodes in their gastrointestinal tracts and lungs. Efficacy of C-076 approached 100% for Dictyocaulus viviparus, Ostertagia ostertagi, Trichostrongylus axei, T colubriformis, and Oesophagostomum radiatum at 50 micrograms/kg. A dosage level of 100 micrograms/kg was required to achieve 97% efficacy against Cooperia punctata. Efficacy of MK-933 at 50 micrograms/kg was variable, but at 100 micrograms/kg, it approached 100% for D viviparus, O ostertagi, Haemonchus placei, T axei, and T longispicularis. Activity against C oncophora was less, reaching 80% efficacy at 200 micrograms/kg.     

The efficacy of ivermectin against nematode parasites of White Fulani calves

Ivermectin was evaluated for anthelmintic activity in calves naturally infected with gastrointestinal helminths. Five of 10 calves were treated subcutaneously with ivermectin at 200 micrograms per kg body weight. One-hundred percent efficacy was indicated against adult and immature Haemonchus, Trichostrongylus, Bunostomum phlebotomum and Oesophagostomum radiatum. Adult Cooperia were also completely eliminated, and a 95.5% reduction was obtained for the immature forms; an 88.7% reduction was obtained for Trichuris spp.     

The anthelmintic efficacy of albendazole against Fasciola hepatica and benzimidazole resistant strains of Haemonchus contortus and Trichostrongylus colubriformis in sheep.

The anthelmintic efficacy of albendazole (methyl [5-(propylthio) - 1H - benzimidazole -2 -yl] carbamate) against immature and adult Fasciola hepatica and against standardised strains of benzimidazole resistant Haemonchus contortus and Trichostrongylus colubriformis was evaluated in experimentally infected sheep. A single intrarumenal treatment of dose rates of 3.8 and 7.6 mg/kg was ineffective against immature (six weeks old) F hepatica. Dose rates of 5.7 and 7.6 mg/kg reduced the number of mature (12 weeks old) F hepatica by 70 and 91 per cent respectively. Dose rates of 5.7 and 7.6 mg/kg removed 92 and 99 per cent of four-week-old, benzimidazole resistant H contortus and 89 and 99 per cent of four-week-old, benzimidazole resistant T colubriformis.     

Efficacy of ivermectin delivered from a sustained-release bolus against inhibited early fourth-stage larvae of Ostertagia ostertagi and other nematodes in cattle.

The anthelmintic efficacy of ivermectin (IVM) delivered from a sustained-release (SR) bolus was evaluated against natural infections with gastrointestinal tract nematodes in 12 crossbred beef heifers in spring. The 12 calves were randomly allotted to 2 groups of 6 calves each. Group-1 calves were treated with an SR bolus designed to deliver 8 mg of ivermectin/d. Group-2 calves were nontreated controls. Cattle groups were kept in separate concrete-floored pens (grass hay nutrition) and slaughter was performed at 35 days after treatment. Fecal egg counts for group-1 calves remained zero after treatment, except for detection of less than 1 egg/g of feces in 1 calf at the time of slaughter; counts in nontreated calves increased. Mean and range of Ostertagia ostertagi inhibited larvae in nontreated calves were 27,093 and 10,622 to 56,368, respectively. Efficacy of the IVM SR bolus was 100% against O ostertagi developing fourth-stage larvae (L4) and inhibited early L4, Haemonchus placei adults, Cooperia punctata and C spatulata adult males, Cooperia spp adult females, Cooperia spp L4, Trichostrongylus colubriformis adults, Bunostomum phlebotomum adults, and Oesophagostomum radiatum adults. Efficacy for O ostertagi and T axei adults was 99.9%. Numbers of nontreated calves infected with C pectinata adult males and Oes radiatum L4 were too low to evaluate efficacy. Calves treated with the IVM bolus gained 10.2 kg, whereas nontreated calves lost 1.8 kg. Abomasal lesions were clearly greater in nontreated calves on the basis of index comparisons of abomasal weight and total live weight and gross pathologic features.     

Anthelmintic efficacy of ivermectin against immature gastrointestinal pulmonary nematodes of calves

Anthelmintic efficacy of ivermectin (greater than or equal to 80% 22,23-dihydroavermectin B1a and less than or equal to 20% 22,23-dihydroavermectin B1b) was evaluated in a controlled experiment against immature nematodes. Twenty calves raised to about 8 weeks of age under nematode-free conditions were allocated into 4 groups. Infective larvae of Haemonchus contortus, Ostertagia ostertagi, Trichostrongylus axei, T colubriformis, Cooperia oncophora, C punctata, Oesophagostomum radiatum, and Dictyocaulus viviparus were given orally to each calf on a staggered schedule 6 to 14 days before treatments. The drug was given subcutaneously when the nematodes were in the early 4th stage of development, and the calves were killed 23 or 24 days later. Group 1 nonmedicated control calves had a geometric mean of 25,102 nematodes; groups 2, 3, and 4 calves given ivermectin at dose rates of 50, 100, or 200 micrograms/kg had reductions of 88.2%, 98.0%, and 99.8%, respectively.     

Efficacy of albendazole for treatment of naturally acquired nematode infections in Washington cattle.

Albendazole, methyl 5-propylthio-1H-benzimidazol-2-yl carbamate, was given as a bolus (7.68 to 8.18 mg/kg of body weight) to cattle naturally infected with gastrointestinal nematodes and lungworms in a controlled trial. Over 99% of adult Ostertagia ostertagi, Trichostrongylus longispicularis, Cooperia oncophora, Nematodirus helvetianus, and Dictyocaulus viviparus were removed by the treatment. Efficacy against immature O ostertagi, early fourth-stage O ostertagi, and Oesophagostomum radiatum was 95.2%, 86.6%, and 96.7%, respectively. In a field trial, the same compound administered in a paste formulation (at approximately 7.5 mg/kg) eliminated over 99% of strongylin and Moniezia eggs from feces of treated cattle.     

Efficacy of oxfendazole against inhibited larvae of Ostertagia ostertagi in naturally infected calves in the southern USA

Forty yearling calves were assigned to four equal groups; three of the groups were treated with oxfendazole at dose rates of 6.75 mg/kg, 4.50 mg/kg, or 2.25 mg/kg bodyweight while the fourth group served as an untreated control. The calves were native to north-east Mississippi, USA, and harboured natural infections of gastrointestinal nematodes. The study was conducted during July when inhibited early fourth-stage larvae may be found in large numbers after their acquisition in the spring. The calves were maintained in separate groups on concrete-floored pens for 17 days before the intraruminal administration of oxfendazole. Seven days after treatment, the calves were slaughtered and the gastrointestinal parasites counted. At all the dose rates examined oxfendazole exhibited an efficacy of at least 99.4 per cent against adults of Haemonchus placei, Trichostrongylus axei, Bunostomum phlebotomum, Cooperia species, T colubriformis, Oesophagostomum radiatum, and Trichuris ovis. The efficacy against adult Ostertagia ostertagi was at least 99.4 per cent at dose rates of 6.75 and 4.50 mg/kg bodyweight, but decreased to 93.7 per cent at 2.25 mg/kg. The efficacy of oxfendazole against inhibited larvae of O ostertagi decreased with dose rate from 78.8 per cent at 6.75 mg/kg, to 58.9 per cent at 4.50 mg/kg and 20.3 per cent at 2.25 mg/kg bodyweight.     

Efficacy of febantel against abomasal nematodes and lungworms in cattle

The efficacy of febantel at a dosage of 5 mg/kg (45.5% paste formulation) against inhibited early 4th-stage larvae (EL4) of Ostertagia ostertagi, other nematodes of the abomasum, and Dictyocaulus viviparus was investigated in 4- to 6-month-old Holstein calves that grazed on pasture heavily contaminated with parasites from February 24 to April 1, 1986 (36 days). In Louisiana, this is the first month of a 3-month period in which increasing numbers of inhibition-prone O ostertagi larvae are acquired, and infection risk with D viviparus may remain high. Three of 4 calves that died of lungworm infection during the pasture-exposure period were necropsied. Large numbers of abomasal nematodes, including inhibited O ostertagi larvae, and large numbers of D viviparus were recovered. Twenty-five calves were randomly allotted by equal distribution of body weight to 2 groups and treated on April 4: placebo-treated calves (n = 13) and febantel-treated calves (n = 12). Equal numbers of treated and control calves were killed at 6 and 7 days, respectively, after treatment. Mean numbers of O ostertagi in control cattle were: adults, 4,931; developing 4th-stage larvae (DL4), 1,119; and inhibited EL4, 3,410. Ostertagia lyrata, Trichostrongylus axei, Haemonchus sp, and D viviparus were well distributed in nearly all control calves. Percentage reduction of O ostertagi in treated calves, when compared with controls, was: adults, 83.6%; DL4, 57.8%; and inhibited EL4, 34.8%. Percentage reductions of other species were: O lyrata, 92.6%; T axei adults, 99.3% and 4th-stage larvae (L4), 100%; Haemonchus sp adults, 66.7%, and L4, 64%; D viviparus adults 90.6%, and immature forms, 97.1%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Efficacy of an albendazole feed formulation against bovine gastrointestinal nematodes including arrested larvae of Ostertagia ostertagi

The efficacy of an albendazole feed premix formulation was compared with that of an albendazole drench suspension for control of gastrointestinal nematodes in 31 beef cattle. The premix (11 cattle) and drench suspension (9 cattle) were found to have similar efficacies at a dosage of 7.5 mg/kg of body weight. When compared with controls (11 cattle), both formulations caused significant (P less than 0.05) reductions in worm counts with an efficacy of 98% or greater against adult Haemonchus placei, Ostertagia ostertagi, Trichostrongylus axei, Cooperia punctata, and C pectinata. There was no significant effect against arrested 4th-stage larvae of O ostertagi. Adverse effects of albendazole treatment were not observed, and the premix formulation was readily consumed by cattle.     

Dose confirmation of moxidectin 0.5% pour-on against adults and fourth-stage larvae of various Cooperia spp. and Trichostrongylus colubriformis in Louisiana

Thirty-five castrate or intact Holstein male calves, ranging in weight from 122 to 210kg, were used in the study. On study Days -15 and -14, all study calves were treated with fenbendazole 10% paste at 10mg/kg to remove existing nematode infections. All cattle had zero egg counts on Day -1. Experimental infections of a mixed species inoculum were administered to all calves on Day 0. The inoculum consisted of Cooperia spp. (primarily C. punctata, but also C. pectinata, C. spatulata, C. oncophora and C. surnabada-total 40,961); Ostertagia ostertagi-1550; Trichostrongylus colubriformis-4996; and Oesophagostomum radiatum-38. Necropsy results from two of three monitor calves slaughtered on Day 6 after infection indicated that Day 6 was an appropriate time to evaluate efficacy of moxidectin against fourth larval stages (L(4)). The remaining 32 calves were randomly allotted to four groups of eight based on body weights. Eight calves (Group 1) were treated with moxidectin 0.5% pour-on at 0.5mg/kg on Day 6 to evaluate efficacy against nematode larval stages; eight control calves (Group 2) were matched with these principals. Eight calves (Group 3) were also treated with moxidectin pour-on at the same dosage on Day 23 in order to determine efficacy against adult nematodes; eight control calves (Group 4) were matched with these principals. In both cases, principals and controls of the Days 6 and 23 treatments were necropsied at 14-15 days after treatment. C. punctata was the only species found in a sufficient number of controls to evaluate moxidectin efficacy against the L(4). Moxidectin pour-on was not effective (P<0.05) against C. punctata L(4) by arithmetic means, but was highly effective based on geometric means. Regardless of whether arithmetic or geometric means were used for percent efficacy calculations, moxidectin pour-on was demonstrated to be highly effective (>99%) against the adult stages of C. oncophora, C. punctata, C. spatulata, C. surnabada, Cooperia spp. adult females and T. colubriformis adults.     

Efficacy of levamisole against immature and mature nematodes in goats with induced infections

Anthelmintic efficacy of levamisole against induced infections with 7- and 21-day-old Haemonchus contortus, Ostertagia circumcincta, Trichostrongylus axei, and T colubriformis was evaluated as an oral drench in goats. Group 1 (n = 8) was not treated, group 2 (n = 8) was given 3.96 mg of levamisole/kg of body weight, group 3 (n = 8) was given 7.92 mg of levamisole/kg, and group 3 (n = 7) was given 11.88 mg of levamisole/kg. Efficacy against all worms was low in goats given 3.96 mg of levamisole/kg, but was high against adult H contortus (99%) and adult T colubriformis (99.7%) in goats given 7.92 mg of levamisole/kg. Although efficacy against adults of all species was high in goats given 11.88 mg of levamisole/kg, some immature worms of all species remained in the abomasa of goats.     

Evaluation of oxfendazole against natural infections of gastrointestinal nematodes in Nigerian calves

The efficacy of oxfendazole was tested in naturally infected Sokoto-Gudali calves at a dosage of 2.8 mg per kg. At this dosage level, oxfendazole showed 100 per cent efficacy against adult and immature forms of Haemonchus spp, Trichostrongylus spp, Bunostomum phlebotomum and Oesophagostomum radiatum. Although efficacy of 100 per cent was recorded for the adult form of Cooperia spp, only 48 per cent reduction was recorded for its immature stages. Similarly, a percentage reduction of 75 was recorded for adult Trichuris spp. No larvae hatched out of a seven-day vermiculite culture of faeces collected from the treated calves 24 h after treatment.