Controlled dosage titration of febantel paste in naturally parasitized cattle

A controlled anthelmintic trial was conducted to determine the efficacy of febantel paste (45.5%) at dosages of 2.5, 5.0, 7.5, and 10.0 mg/kg in calves harboring natural gastrointestinal nematode infections. Dosages of 5.0, 7.5 and 10.0 mg of febantel/kg of body weight were greater than 96% effective in removing adults of Haemonchus contortus, Ostertagia spp, Cooperia spp, and Oesophagostomum radiatum. The 2.5 mg/kg dosage was considered suboptimal because of low efficacy against Ostertagia and Cooperia spp. Efficacies against Trichostronglylus axei, Trichuris spp, Bunostomum phlebotomum, and Stronglyloides papillosus were difficult to determine because fewer numbers of these nematodes were recovered. Efficacies of febantel paste against immature bovine parasites ranged from 83.62% to 97.72%.     

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.     

Resistance of Teladorsagia circumcincta in goats to ivermectin in the Netherlands

Resistance of Teladorsagia circumcincta in goats to ivermectin In 2005, suspected ivermectin resistance of gastrointestinal nematodes was investigated in 17 goats on a farm in the Netherlands, using a faecal egg count reduction test combined with faecal larval cultures. Eight goats were treated orally with 0.2 mg/ kg ivermectin on 1 August 2005 and the other nine goats served as untreated controls. Faeces were collected from all goats on 1 August and on 12 August. Faecal egg counts were reduced by 80.6% in goats receiving ivermectin. On the basis of faecal larval cultures and the egg counts, ivermectin was found to be 100% effective against Haemonchus contortus, 15.0% effective against Teladorsagia circumcincta, and 93.3% effective against Trichostrongylus spp. The effect of levamisole and oxfendazole on gastrointestinal nematodes was also evaluated. Nine goats were treated subcutaneously with 5 mg/kg levamisole and seven goats orally with 4.5 mg/kg oxfendazole on 12 September On the basis of faecal egg counts performed on 12 and 22 September, levamisole reduced the total egg count by 95.4% and oxfendazole reduced the egg count by 85.8%. Differentiation of pooled faecal larval cultures revealed that levamisole was 99.9% effective against H. contortus, 81.9% effective against T. circumcincta, and 99.5% against Trichostrongylus spp. Oxfendazole was 75.5% effective against H. contortus, 33.2% effective against T. circumcincta, and 100% effective against Trichostrongylus spp. On 28 October the nine goats that were still present on the farm were orally treated with 0.4 mg/kg ivermectin. Faecal egg counts and differentiation of pooled larval cultures of faecal samples collected on 28 October and 9 November, respectively, revealed that total egg counts were reduced by 93.1%. Ivermectin was 49.1% effective against T. circumcincta but 100% effective against H. contortus and Trichostrongylus spp. Thus H. contortus appears to be resistant to oxfendazole and T. circumcinta appears to be resistant to oxfendazole and ivermectin. This is the first documented case of ivermectin resistance of a gastrointestinal nematode of small ruminants in the Netherlands.     

Effect of gastrointestinal nematode and liver fluke infections on weight gain and reproductive performance of beef heifers

Spring born, crossbred beef heifers (n=372) were utilized over four years to measure reductions in body weights, reproductive performance and calf weights caused by gastrointestinal nematodes (primarily Ostertagia ostertagi) and the bovine liver fluke (Fasciola hepatica) and to differentiate losses attributable to each type of parasitism. Each year, weaned heifers were allotted to one of the four treatment regimens: Group 1, untreated controls; Group 2, treated for nematodes; Group 3, treated for liver fluke; and Group 4, treated for both nematodes and liver fluke. Nematodes were controlled with subcutaneous injections of either ivermectin (Ivomec, Merial) or doramectin (Dectomax, Pfizer), both at the recommended dose of 200 ug/kg bodyweight. Clorsulon (Curatrem, Merial) drench was given at the recommended rate of 7 mg/kg bodyweight to control flukes. Treatments and fecal collections were initiated at allotment each year and were repeated at 28-84-day intervals until palpation for pregnancy diagnosis. Open heifers were removed from the study at this time. Treatment dates were based on expected length of treatment efficacy, the stage of growth of the heifers and the seasonal risk of infection by the parasites. Pregnant females were pooled and received their assigned treatments prior to their calving and breeding seasons and remained together until their calves were weaned. Heifers treated for nematode infections were heavier and had higher condition scores (P<0.01) than untreated control heifers at initiation of breeding, and maintained that difference through pregnancy diagnosis. Liver fluke infection did not affect heifer gains or condition scores prior to palpation (P<0.01). At palpation, heifers treated for both forms of parasitism had the highest condition scores and weight gains (P<0.01), and also higher pregnancy rates than control heifers and heifers treated for nematodes only (P<0.01). Pregnancy rates for heifers treated for flukes only were not significantly different from those treated for both nematodes and flukes. Heifers treated for nematodes weaned heavier calves than those not treated for nematodes (P<0.05).     

Controlled test of the efficacy of the feed premix formulation of crufomate on the parasites of the gastrointestinal tract and lungs of dairy calves

Activity of the feed premix formulation (M-1839) of crufomate against helminths of the gastrointestinal tract and lungs of cattle was determined in a controlled test. Eight calves were treated and 7 were nontreated. The dosage rate of crufomate was 17 mg of active drug/kg of body weight daily for 3 consecutive days. Removal activity was high against mature Cooperia oncophora (99%) and C punctata (96%) and immature Cooperia spp (87%). Removal of mature Ostertagia ostertagi was 68%. The removal of strongyloides papillosus and Bunostomum phlebotomum was 72% and 67%, respectively, but only a few specimens were present in the nontreated calves. Efficacies against the other mature and immature species of nematodes ranged from 0% to 34%. Lungworms (Dictyocaulus viviparus) were not effectively removed.     

Evaluation of three formulations of fenbendazole (10% suspension, 0.5% pellets, and 20% premix) against nematode infections in cattle

Anthelmintic efficacies of 3 formulations of fenbendazole were evaluated in cattle naturally parasitized with nematodes: a 10% oral suspension, 0.5% pellets as a top dressing on feed, and a 20% premix. All formulations of fenbendazole were greater than 99% effective in removing adults of Haemonchus contortus, Ostertagia spp, Cooperia spp, and Oesophagostomum radiatum. Fenbendazole was greater than 96% effective in removing adults of Strongyloides papillosus and greater than 85% effective in the removal of Trichuris sp. Fenbendazole was greater than 96% effective against immature nematodes, which were thought to be primarily Cooperia spp. Adverse reactions were not observed in calves treated with the 3 formulations of fenbendazole.     

Anthelmintic activities of B1a fraction of avermectin against gastrointestinal nematodes in calves

Anthelmintic activities of the B1a fraction of avermectin were evaluated in a controlled experiment. Twenty 12-week-old calves artificially infected with gastrointestinal nematodes were allotted to four groups. Calves in group 1 were used as nonmedicated controls; other calves in groups 2, 3, and 4 were given (orally) B1a avermectin at dosage levels of 50, 100, and 200 microgram/kg of body weight, respectively. These treatments were given 35 days after calves were inoculated with infective nematode larvae. In groups 2, 3, and 4, overall reductions (based on geometric means) were 98.6%, 98.7%, and 98.4%, respectively. These reductions were highly significantly different (P less than 0.01) from the control calves. Nematodes in the calves were Haemonchus contortus. Ostertagia ostertagi, Trichostrongylus axei, T colubriformis, Cooperia oncophora, C punctata, and Oesophagostomum radiatum.     

Anthelmintic activity of Croton zehntneri and Lippia sidoides essential oils

Because of the development of anthelmintic resistant populations, the search for new drugs is essential to maintain the productivity of small ruminants. The aim of this study was to evaluate the anthelmintic activity of Croton zehntneri and Lippia sidoides essential oils and their major constituents, anethole and thymol. The effects of these oils and their constituents were determined by in vitro assays with the eggs and larvae of the sheep gastrointestinal nematode Haemonchus contortus. The two essential oils were evaluated on intestinal nematodes of mice at 800 mg kg(-1) dose. In the last experiment, the mice were treated with larger doses of L. sidoides, 1200 and 1600 mg kg(-1). The essential oils and their constituents prevented more than 98% of the H. contortus eggs from hatching at a concentration of 1.25 mg ml(-1) and inhibited more than 90% of H. contortus larval development at a concentration of 10 mg ml(-1). At a concentration of 800 mg kg(-1), the two essential oils were 46.3% and 11.64% effective against Syphacia obvelata and Aspiculuris tetraptera. At 1200 and 1600 mg kg(-1), L. sidoides essential oil's efficacy on the mouse worm burden was 57.6% and 68.9%, respectively. The fact that L. sidoides essential oil was almost 70% effective against mouse intestinal nematodes indicates it should be evaluated against gastrointestinal nematodes of sheep and goats.     

Reindeer as hosts for nematode parasites of sheep and cattle

The reindeer husbandry range of Scandinavia overlaps with sheep, goat, and cattle pastures. The aim of this study was to determine whether reindeer are suitable hosts for ovine or bovine nematode parasites, and thus may spread these parasites into the reindeer husbandry regions. To render worm-free, twelve 4-month-old male reindeer calves, six lambs, and six bovine calves were given ivermectin at 200 microg/kg body weight. Five weeks post-treatment, six reindeer calves were each artificially dosed with 10,000 third-stage larvae (L3) of gastrointestinal nematodes derived from sheep, and an additional six reindeer with L3 derived from cattle. Lambs and bovine calves received the same dose of ovine and bovine larvae as reindeer, from the same larval source, respectively. Faecal samples collected on five occasions after the larval dosing revealed that by the fourth week, all reindeer calves, lambs, and bovine calves were infected. Animals were slaughtered on days 40 (reindeer) or 47 (lambs and bovine calves) after the larval dosing. Reindeer calves were most susceptible to L3 derived from sheep. The overall mean intensity of Haemochus contortus, Trichostrongylus axei, and Teladorsagia circumcincta, did not differ between reindeer and sheep; however, early fourth-stage larvae of H. contortus were more abundant in reindeer (p = 0.002). The establishment of bovine-derived Ostertagia ostertagi was similar in reindeer (62%) and bovine calves (57%), but larval inhibition was much higher in reindeer (91%, p < 0.001) than in cattle (31%). Very poor establishment of bovine derived Cooperia oncophora was recorded in reindeer calves (2%) compared with bovine calves (59%). These results show that young reindeer are susceptible hosts to the important gastrointestinal parasites of sheep (T. circumcincta, H. contortus) and cattle (O. ostertagi), as well as being a suitable host for T. axei.     

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.     

Effects of parenteral administration of doramectin or a combination of ivermectin and clorsulon on control of gastrointestinal nematode and liver fluke infections and on growth performance in cattle

OBJECTIVE: To compare effects of an injectable doramectin preparation with those of an injectable ivermectin-clorsulon preparation on control of gastrointestinal nematodes and liver flukes and on growth performance in cattle. DESIGN: Randomized complete block design. ANIMALS: 60 crossbred calves. PROCEDURES: Calves (20/treatment group) were treated with doramectin or ivermectin-clorsulon or were not treated. Fecal samples were collected for nematode and Fasciola hepatica egg counts on day 0 and for up to 140 days after treatment. Cattle were weighed before treatment and at 28-day intervals until day 140. RESULTS: From day 7 through day 49, nematode egg counts for calves treated with doramectin or with ivermectin-clorsulon were significantly lower than those for untreated control calves. As the study progressed beyond day 56, the percentages of cattle with fluke eggs in their feces increased, but differences in regard to these percentages were not detected among the 3 groups. Average daily gain for the doramectin-treated cattle (0.79 kg/d [1.74 lb/d]) was significantly greater than that for the cattle treated with ivermectin-clorsuIon (0.71 kg/d [1.56 lb/d]); values for both groups were significantly greater than that for the control cattle (0.62 kg/d [1.37 lb/d]). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that doramectin had a greater impact on subclinical gastrointestinal tract parasitism in calves, as demonstrated by growth performance, than did ivermectin-clorsulon. In the Gulf Coast region of the United States, spring-born nursing beef calves may have minimal grazing exposure to F hepatica during the peak fluke transmission period; therefore, mature fluke burdens may be negligible at the beginning of the fall season.     

Efficacy of morantel against nematode populations in calves exposed on a pasture stocked for two years with morantel sustained-release bolus-treated calves

Two groups of 10 parasite-free calves were maintained either for 2 weeks on a pasture grazed by nonmedicated cattle (pasture A) or for 3 weeks on a pasture grazed by morantel sustained-release bolus-treated cattle (pasture B) for the preceding 2 years. After a 4-week holding period to allow for maturation of acquired gastrointestinal nematodes, 5 calves from each group were administered a therapeutic dose (10 mg/kg of body weight) of morantel tartrate. All calves were necropsied 1 week later, and the abomasal and small intestinal nematodes were isolated, identified, and enumerated. A comparison of efficacies between nonmedicated and morantel tartrate-treated calves of each pasture demonstrated that morantel was equally effective against the gastrointestinal nematode infections, regardless of infection source (ie, pasture A vs pasture B). The overall nematode reductions due to morantel tartrate treatment of calves that grazed pastures A and B were 98% and 96%, respectively. It was concluded that the sensitivity of gastrointestinal nematodes to morantel tartrate was not diminished in calves maintained on pasture B, which had been stocked with morantel sustained-release bolus-treated calves for the preceding 2 grazing seasons.     

Use of diagnostic markers to monitor fasciolosis and gastrointestinal nematodes on an organic dairy farm

A 12-month study was conducted to assess and monitor gastrointestinal tract nematodes and liver fluke in cohorts of cattle on a Scottish organic dairy farm. Various diagnostic markers for helminth parasites of cattle from different age groups were assessed monthly from April 2007 to March 2008. First season grazing stock were subjected to significant challenge from Ostertagia ostertagi nematodes as reflected in serum pepsinogen concentrations, which rose markedly in the second half of the grazing season. In addition, plasma albumin concentrations decreased and faecal egg counts (FEC) increased moderately, indicating exposure to both O ostertagi and probably Cooperia oncophora. Second season grazing animals had a peak FEC early in the grazing period, suggestive of a potential carry-over of Ostertagia species infection ('Type 2') during housing. All classes of cattle showed evidence of fluke (Fasciola hepatica) infection. Adult cow exposure to O ostertagi and fluke was estimated via the use of ELISA testing to detect antibodies to O ostertagi and F hepatica and the high levels detected suggested a significant exposure response. Despite low stocking densities and sympathetic grazing management, there was a significant challenge to all grazing stock from gastrointestinal nematodes and liver fluke.     

Helminthiases in newly established large-capacity breeding stations for cattle]

Invasions of gastrointestinal nematodes proved to be the most frequent helminthiases in new-established large-capacity herds of cattle according to the results of parasitary examinations of cattle in one locality in the Tachov district. The nematodes, especially Oesophagostomum spp., Haemonchus contortus, Cooperia spp., Trichostrongylus spp., occurred in animals of all age categories. The Ostertagia spp., Chabertia ovina, Nematodirus spp., Bunostomum phlebotomum and Trishuris spp. participated in the invasions to a smaller extent. The first eggs can already be found in three months old calves. Strongyloidosis can be diagnosed in the first month of age in calves [5%], the incidence rate increasing up to the age of five months, then it begins to decrease. Taenasis was found out in six months old calves [4.4% and11.6%]. Reclamations of pastures reduced the incidence of fasciolosis to the minimum rate; its invasions were heavy before establishing the large-capacity herds of cattle. Dictyocaulosis was not found in the large-capacity herds of cattle at all, due to the same reasons. Not only were nematode eggs proved, but also larvae to develop to the stages capable of invasion [Chabertia ovina, Haemonchus contortus, Oesophagostomum spp., Strongyloides papillosus] in dry excrements on railings of pens, on slatted floors and walls of the calf-sheds that were investigated.     

Multiple Anthelmintic Resistance in Haemonchus Contortus on a Sheep Farm in Kenya

Multiple resistance to albendazole, thiophanate, levamisole and orally administered ivermectin was detected in an isolate of Haemonchus contortus in sheep on a farm where benzimidazole resistance had already been identified. Following a faecal egg count reduction test, this was confirmed by both critical and controlled anthelmintic tests. Different groups of sheep infected naturally or given an experimental infection with the benzimidazole-resistant isolate were treated with the recommended doses of various anthelmintics. Compared to the control group, the percentage reductions in the faecal egg counts of sheep treated with albendazole, thiophanate, levamisole and ivermectin varied between 38.2% and 79.1% and the residual worm counts between 27.3% and 57.5%. The results indicate the presence of multiple anthelmintic resistance in this isolate of H. contortus. Sheep treated with closantel showed 100% reductions in faecal egg and worm counts, indicating that this drug was very effective against the population of H. contortus on the farm.     

Further tests of activity of levamisole on Ostertagia ostertagi in dairy calves with notes on overwinter survival of gastrointestinal helminths on pasture

Two controlled tests were conducted in 1981 and 1982 in dairy calves on the University of Kentucky research farm to determine activity of the bolus formulation of levamisole given at the dose rate of 8 mg/kg against naturally occurring infections of Ostertagia ostertagi. Removal efficacies of mature O ostertagi were 98% in the 1981 test (3 treated and 3 nontreated calves) and 94% in the 1982 test (7 treated and 8 nontreated calves). Against immature Ostertagia spp, removal efficacies were 100% and 65% for the 1st and 2nd tests, respectively. The calves were grazed on the same pasture as dairy calves in previous controlled tests in 1979 and 1980 where activity of levamisole against mature O ostertagi (data recently published) was much less than in the present tests. It does not appear that the poor performance in the early tests can be attributed to the drug resistance phenomenon. Data on overwinter survival (119 days) of free-living stages of gastrointestinal parasites on pasture were derived from the nontreated calves in the 1982 controlled test. The calves, raised helminth-free, were placed on the pasture on Apr 5, 1982. Helminths recovered at necropsy of the calves, besides O ostertagi, included Trichostrongylus axei, Nematodirus helvetianus, Nematodirus spp, Cooperia oncophora, Trichuris spp, and Moniezia spp. The lung-worm, Dictyocaulus viviparus, previously found in cattle on the farm, was not found in these calves.     

Prophylactic efficacy of an ivermectin sustained-release bolus against challenge exposure with gastrointestinal and pulmonary nematode infective larvae in calves

Twelve Holstein calves were used to determine the prophylactic efficacy of ivermectin against challenge exposure with gastrointestinal and pulmonary nematodes. Two groups of 6 calves (mean body weight, 205 kg) each were formed by restricted randomization according to body weight. Group-1 calves served as nonmedicated controls. Each calf of group 2 was orally given one prototype sustained-release bolus designed to deliver ivermectin at a continuous daily dose of 8 mg. Third-stage nematode infective larvae were given to the calves on posttreatment days 28 and 42. The calves were euthanatized 77 or 78 days after treatment. Ivermectin was 100% effective (P less than 0.05) in preventing the establishment of infection by Haemonchus placei, Ostertagia ostertagi, Cooperia spp (C punctata, C oncophora, C surnabada), Nematodirus helvetianus, Oesophagostomum radiatum, and Dictyocaulus viviparus and was greater than 99% effective against Trichostrongylus axei. Incidental infection by Trichuris spp was reduced by 94% (P = 0.08).     

Efficacy of eprinomectin pour-on against gastrointestinal nematodes and the nasal bot fly (Oestrus ovis) in sheep

The efficacy of the pour-on formulation of eprinomectin, at a dose rate of 0.5 mg/kg bodyweight, was assessed in sheep against three main species of gastrointestinal nematodes and against the nasal bot fly, Oestrus ovis, and some pharmacokinetic parameters were determined for 21 days after the treatment. By comparison with untreated control sheep, infected experimentally with Haemonchus contortus, Teladorsagia circumcincta and Trichostrongylus colubriformis, eprinomectin was 100 per cent effective against the two abomasal species and 99.5 per cent effective against T. colubriformis. In ewes naturally infected with the nasal bot fly, the efficacy of the drug against O. ovis was 97.7 per cent. The mean (se) systemic area under the curve (AUC) was 56.0 (26.2) ng/day/ml and the mean residence time was 5.3 (1.0) days, but there were wide variations between individual sheep.     

Gastrointestinal nematodes of small ruminants: life cycle, anthelmintics, and diagnosis.

Strongylid gastrointestinal nematodes are an important cause of disease and economic loss in small ruminants. These parasites are particularly important in the eastern United States where the bloodsucking parasite Haemonchus contortus is the predominant species. Sheep and goats are infected with gastrointestinal nematodes while grazing and the biology of the infective larvae on the pastures is important in planning effective control programs. Fecal egg counts can be used to monitor control programs and drug efficacy and evaluate levels of pasture contamination.