Efficacy of clorsulon against mature, naturally acquired Fasciola hepatica infections in cattle and sheep

Clorsulon (3.5 or 7 mg/kg of body weight) was given orally to mature cows (dairy or beef) and to mature mixed-breed sheep harboring patent infections of Fasciola hepatica. Eighteen animals of each species were assigned to a control group (drug vehicle) or to 1 of 2 treatment (3.5 or 7.0 mg/kg) groups of 6 animals each. On posttreatment days 8 (cows) or 14 (sheep), the animals were slaughtered for recovery of flukes. In cows, the efficacy (P values for treatment groups vs control) of clorsulon against infections of mature F hepatica was 99.21% (P less than or equal to 0.0065) at 3.5 mg/kg and was 100% (P less than or equal to 0.0039) at 7 mg/kg. In sheep, the efficacy was 93.33% (P less than or equal to 0.0104) at 3.5 mg/kg and was 100% (P less than or equal to 0.0039) at 7 mg/kg. These results indicate that clorsulon is a highly effective compound for the treatment of mature F hepatica in cows and sheep.     

Efficacy of clorsulon for the treatment of experimentally induced infections of Fasciola hepatica in goats

A dose titration study was undertaken to determine the efficacy of clorsulon against the adult stage of Fasciola hepatica in goats. Thirty-nine goats were experimentally infected with metacercariae of F hepatica. At 14 weeks after infection, each goat was assigned randomly to 1 of 5 groups. Goats in groups 1 to 4 received a single oral administration of clorsulon at dosages of 3.5, 7, 11, and 15 mg/kg of body weight, respectively. The fifth group of goats (control group) was infected with F hepatica, but were not treated with clorsulon. Postmortem examination of goats at 3 weeks after treatment revealed mean reductions in numbers of flukes of 83, 98, 99, and 100% for groups 1 to 4, respectively. Mean percentage of reduction in eggs following treatment of groups was 82, 98, 100, and 100%, respectively. The clinical effects of clorsulon in 24 goats that were not infected with F hepatica were studied. Goats in groups 1 to 3 received a single oral administration of clorsulon at dosages of 7, 21, and 35 mg/kg, respectively, every other day for a total of 3 doses/goat. Group-4 goats (control group) received a vehicle placebo. Goats in group 3 were subject to postmortem examination at 14 days after dosing. Abnormal signs or lesions that could be attributed to clorsulon were not found in any goat.     

Influence of ivermectin and clorsulon treatment on productivity of a cow-calf herd on the southern Oregon coast.

The reproductive performance of beef cows and the weight gain of their calves was evaluated after oral administration of clorsulon or clorsulon in combination with the subcutaneous administration of ivermectin. One hundred and fifty pregnant cows harboring infections of Fasciola hepatica were assigned to one of three treatment groups: Group 1 comprising 50 unmedicated controls; Group 2, 50 cows treated with clorsulon orally at 7 mg kg-1; Group 3, 50 cows treated with clorsulon orally at 7 mg kg-1 and ivermectin subcutaneously at 200 micrograms kg-1. Weights and body condition scores of the cows were measured and fecal and blood samples were taken at trial initiation and days 158 and 270. Pregnancy status was also determined at day 270. Weights and body condition scores were measured for the calves at days 158 and 270. Adjusted 205 day weaning weight of the calves was calculated and analyzed for differences between treatment groups. Four sets of tracer calves were used periodically throughout the trial to monitor the helminth challenge to the herd. Both gastro-intestinal nematodes and liver flukes were transmitted to the tracer calves during the entire trial. Even in the face of continual helminth challenge, beef cows treated with combined clorsulon/ivermectin conceived approximately 2 weeks earlier than their untreated counterparts and their calves had better body condition scores and weights than untreated calves.     

Comparative efficacy of clorsulon and albendazole against Fasciola hepatica in cattle

In a dosage-confirmation trial, anthelmintic activities of clorsulon and albendazole against Fasciola hepatica were evaluated and compared. Twenty-eight cattle (8 to 12 months old) with natural F hepatica infections were randomly allotted to 4 groups of 7 cattle each: group 1, no treatment (controls); group 2, clorsulon suspension given orally at 3.5 mg/kg of body weight; group 3, clorsulon suspension given orally at 7 mg/kg; and group 4, albendazole paste given orally at 10 mg/kg. At necropsies, performed 7 and 8 days after treatment, control cattle harbored a geometric mean of 133.2 F hepatica, 16.0 of which were immature. Clorsulon administered at 3.5 mg/kg or 7 mg/kg resulted in greater than 99% removal of F hepatica, including immatures. Albendazole treatment resulted in a 76% overall reduction in F hepatica, including a 91% reduction of immatures. Fascioloides magna also were found in the cattle, but neither clorsulon nor albendazole caused significant reductions of the parasite. Adverse reactions to the 2 drugs were not observed.     

Prophylactic efficacy of clorsulon against Fasciola hepatica in calves and sheep

A daily oral 5 mg kg-1 dose of clorsulon for 28 days in calves given Fasciola hepatica cysts at 3, 5, and 7 days after initiation of treatment was highly effective in reducing worm burdens (98%) and preventing liver pathology. In similarly infected and treated sheep, clorsulon showed little effect as a prophylactic for delaying the onset of liver pathology. The size of flukes recovered from treated sheep was reduced. Although clorsulon prevented development of fascioliasis in treated calves, the host antibody response was qualitatively similar to that of untreated infected calves, but the magnitude of the response was reduced. Blood clorsulon levels in calves rose to 2.90 micrograms ml-1 within the first week of treatment then fluctuated between 2.65 and 2.90 micrograms ml-1 for the next two weeks. Clorsulon levels in sheep were 0.50-0.60 micrograms ml-1 lower than those in calf blood. The difference in bioavailability of clorsulon between sheep and calves may have contributed to differences in efficacy of the drug.     

Efficacy and safety of clorsulon used concurrently with ivermectin for control of Fasciola hepatica in Florida beef cattle

The safety and anthelmintic efficacy of clorsulon (7 mg/kg of body weight, orally) given concurrently with ivermectin (0.2 mg/kg, subcutaneously) for control of Fasciola hepatica were evaluated in 75 crossbred beef cattle. Twenty-three control animals were given only ivermectin. Fluke egg counts were significantly lower (P less than 0.0001) in clorsulon-treated animals by day 14 after treatment than before treatment (base line) and were significantly lower (P less than 0.005) after treatment in clorsulon-treated animals than in controls. There was no significant change in fluke egg counts of controls after treatment. The efficacy of clorsulon in reducing F hepatica egg counts was 99%. Clorsulon showed poor efficacy against paramphistomes. Adverse reactions were not observed.     

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.     

Field trial on comparative efficacy of four fasciolicides against natural liver fluke infection in cattle

A controlled trial was conducted to evaluate the current efficacy of albendazole (ABZ), rafoxanide (RFX), triclabendazole (TRC) or clorsulon (CLS) against Fasciola hepatica in naturally infected cattle. This trial was conducted in Turkey during the spring, the time of year when liver fluke infection is endemic. Fifty crossbred cattle were selected for inclusion in the trial based on finding eggs of F. hepatica in the feces. The cattle were weighed and randomly allotted into five groups of 10 cattle and treatments were as follows: Group 1 served as non-treated control (CONT), Group 2 was treated orally with ABZ at 12 mg/kg, Group 3 was treated orally with RFX at 10 mg/kg, Group 4 received TRC orally at 12 mg/kg and Group 5 received CLS administered subcutaneously (s.c.) at 2 mg/kg. On day 0 (inclusion day), individual fecal samples were collected on days 0 (inclusion day), 7, 14, 28 and 56, after treatment. The drug efficacy was assessed as a percentage of the egg or fluke reduction and body weight gain relative to the untreated control. The results in the study showed a mean reduction of egg counts by 66.7%, 68.2%, 78% and 84.2% in Groups 2-5, respectively. In conclusion, our results indicate that CLS is a highly effective compound for the treatment of F. hepatica in cattle under these field conditions.     

The efficacy of triclabendazole and other anthelmintics against Fasciola hepatica in controlled studies in cattle

In eight controlled tests 274 cattle were used to assess the efficacies of triclabendazole, albendazole, clorsulon, nitroxynil, oxyclozanide and rafoxanide against Fasciola hepatica. Against one-, two- and four-week-old early immature fluke the mean efficacies of triclabendazole given orally at 12 mg/kg were 88.1, 95.3 and 90.7 per cent, respectively. Clorsulon, nitroxynil and rafoxanide administered at recommended dose rates showed negligible activity against these stages of the parasite. Against six- and eight-week-old infections the mean efficacies of triclabendazole at 12 mg/kg were 87.5 per cent and 95.7 per cent, respectively. Against F hepatica aged six weeks, albendazole and oxyclozanide showed no activity and clorsulon, nitroxynil and rafoxanide had only slight to moderate activity. The efficacies of triclabendazole, clorsulon, nitroxynil and rafoxanide against 10- or 12-week-old parasites were 100, 99.0, 99.1 and 90.1 per cent, respectively. Albendazole and oxyclozanide showed poor efficacy against 12-week-old infections.     

Evaluation of the comparative efficacy of a moxidectin plus triclabendazole pour-on solution against adult and immature liver fluke, Fasciola hepatica, in cattle

The objective of this study was to evaluate the efficacy of a pour-on solution containing moxidectin plus triclabendazole (MOX plus TCBZ) against immature and adult stages of the liver fluke in cattle and compare the efficacy with other commercially available preparations. To this end, 104 male Holstein-Friesian calves aged between 3 and 4 months, were randomly allocated to 13 groups of eight animals each, and infected with approximately 500 Fasciola hepatica metacercariae. One group remained untreated, four groups were treated with MOX plus TCBZ at a dose rate of 0.1mL/kg, four other groups were treated with ivermectin (IVM) plus clorsulon injectable at a dose rate of 0.02mL/kg, and the remaining four groups were treated with IVM plus closantel pour-on at a dose rate of 0.1mL/kg. Each treatment was applied to one of the groups at 4 weeks, 6 weeks, 8 weeks and 12 weeks after the experimental infection. At necropsy (99-102 days after infection), all untreated animals were infected with a minimum of 30 flukes. The MOX plus TCBZ treated animals had significantly (P<0.0001) lower fluke counts compared to the untreated control animals at all time points after treatment. Efficacy against 8-week old and adult flukes was >99.5%. For 6-week old immature fluke, the efficacy was 98.0% and for 4-week old immature fluke the efficacy was 90.9%. The IVM plus closantel pour-on treated animals had significantly lower fluke counts compared to the untreated control animals for adult and 8-week old flukes (P<0.0001), and for 6-week old flukes (P=0.002). The efficacy was 26.8%, 68.2%, 90.6% and 99.3% against 4-week, 6-week and 8-week old immature flukes, and adult flukes respectively. The IVM plus clorsulon treated animals had significantly lower fluke counts compared to the untreated control animals for adult (P<0.0001) and 8-week old (P<0.05) flukes. The efficacy was 29.7%, 43.4%, 53.2% and 99.2% against 4-week, 6-week and 8-week old immature flukes, and adult flukes respectively. For treatments at 4, 6 and 8 weeks after infection, the fluke counts were significantly (P<0.0001) lower for the MOX plus TCBZ treatment than for IVM plus closantel or IVM plus clorsulon. The results confirm the high efficacy (>90%) of the MOX plus TCBZ pour-on combination against 4-week old to adult liver fluke in cattle. The IVM plus closantel pour-on combination was effective (>90%) against 8-week old and adult flukes, but had low efficacy against 4- and 6-week old fluke. The IVM plus clorsulon injectable combination was effective (>90%) against adult fluke only.     

Efficacy of febantel paste against naturally acquired gastrointestinal nematodes of cattle

Twenty calves with naturally acquired gastrointestinal nematode infections were assigned to 10 replicates of 2 calves each and were treated with febantel paste (5 mg/kg of body weight, PO) or an equivalent volume of paste vehicle (control calves). Adverse reactions were not observed after febantel treatment. At necropsy, gastrointestinal nematode counts in febantel-treated calves, compared with control calves, were reduced by over 99% for all major species except Trichuris discolor, counts of which were reduced by only 69%. Counts of gastrointestinal nematode eggs in feces of febantel-treated calves were reduced by 100% after treatment.     

Use of febantel or ivermectin for treatment of calves with experimentally induced Bunostomum phlebotomum infection

In the first of 2 separate trials, the efficacy of febantel, given at a dosage of 5 mg/kg of body weight, was assessed in calves with 60-day experimentally induced Bunostomum phlebotomum infection. Ten calves were given febantel paste, and 10 were given the vehicle only. All 20 calves were necropsied 7 days after cessation of treatment. Compared with untreated calves, febantel-treated calves harbored 99.4% fewer nematodes. In the second trial, the efficacy of ivermectin, given as a paste formulation at a dosage of 0.2 mg/kg, was assessed in calves with experimentally induced B phlebotomum infection. Ivermectin was given at 18 (n = 6) and 60 (n = 6) days after infection. At each treatment date, 3 additional calves were given vehicle only. At 67 days after infection, all calves were euthanatized. Efficacies of ivermectin against 18- and 60-day infections were 100 and 99.8%, respectively. Both anthelmintic preparations were easily administered, and adverse reactions were not observed.     

Herd evaluation of Fasciola hepatica infection levels in Louisiana cattle by an enzyme-linked immunosorbent assay

An enzyme-linked immunosorbent assay (ELISA) was evaluated as a method of determining relative immunoconversion rates in calves and how immunoconversion rates and strength of optical density values correlate with prevalence of Fasciola hepatica fecal egg shedding. Ten to 55 calves and cows were examined from each of 10 separate beef cattle herds in central and southern Louisiana. Infection prevalence rates for calves averaged 8% higher when ELISA optical density values were used than those when fecal egg count data were used. Of 55 calves in 8 herds that were ELISA positive, 39 were shedding F hepatica eggs; of 53 calves that were shedding eggs, 14 were ELISA negative. Significant correlation of calf fecal and ELISA prevalence was observed for 8 herds by linear regression analysis. A chi 2 analysis showed that calf ELISA and fecal egg shedding data were not independent. Results indicate that positive ELISA reactions for as few as 10 to 15 calves from the fall calf crop of a given herd are sufficiently accurate to be used to assess F hepatica herd infection rates, the likelihood of liver condemnations at feedlot destinations, and variation between individual farms in fascioliasis infection risk. The test was less valuable as a diagnostic test when used in adult animals previously exposed to F hepatica or on an individual animal basis.     

Efficacy of orally administered moxidectin against naturally acquired gastrointestinal nematodes in cattle.

Anthelmintic efficacy of moxidectin, an experimental antiparasitic macrocyclic lactone, was evaluated in a group of 15 calves harboring naturally acquired gastrointestinal nematodes. Three groups of 5 calves each served as untreated controls (group 1) or principals that were given moxidectin PO at the rate of 0.2 mg/kg (group 2) or 0.4 mg/kg (group 3) of body weight. Equal numbers of control and treated calves were necropsied for parasite recovery on days 10 (3 control and 3 of each treatment group) and 11 (2 control and 2 of each treatment group) after treatment. Efficacies at both doses were greater than 99.8 and 99.9% against active and inhibited larvae and adults of Ostertagia spp, respectively. The overall mean efficacy of each dose was greater than 99.9%.     

Evaluation of clorsulon against immature Fascioloides magna in cattle and sheep

Efficacy of clorsulon was evaluated against infection with immature Fascioloides magna in 24 cattle and 12 sheep. Infections were induced by oral administration of 600 metacercariae/host. In cattle, clorsulon at dosages of 7 and 21 mg/kg of body weight was 65 and 100% effective against 8-week-old flukes, and 20 and 74% effective against 16-week-old flukes, respectively. In sheep, clorsulon at a dosage of 21 mg/kg was 92% effective against 8-week-old flukes. Significantly (P less than 0.05) more F magna were recovered from untreated sheep than from untreated cattle.     

Efficacy of clorsulon and albendazole against Fascioloides magna in naturally infected white-tailed deer

The efficacy of clorsulon and of albendazole against Fascioloides magna were evaluated in 36 naturally infected white-tailed deer (Odocoileus virginianus) in southern Texas. A single oral dose of clorsulon suspension (12 to 30 mg/kg of body weight; mean = 24 mg/kg) was given to each deer and killed 153 (92%) of 167 mature flukes and 4 (80%) of 5 immature flukes recovered at necropsy. A single oral dose of albendazole paste (17 to 46 mg/kg; mean = 26 mg/kg) was given to each deer and killed 148 (89%) of 167 mature flukes and 4 (67%) of 6 immature flukes recovered at necropsy. In 82 nontreated control deer, 271 live flukes were recovered; dead flukes were not recovered.     

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 difloxacin in calves experimentally infected with Mannheimia haemolytica

OBJECTIVE: To determine the efficacy of difloxacin, a novel fluoroquinolone antibiotic, in calves experimentally infected with Mannheimia haemolytica (formerly Pasteurella haemolytica). ANIMALS: Seventy-two 3-month-old Holstein calves. PROCEDURES: Calves were inoculated with M haemolytica intratracheally; after they developed clinical signs of pneumonic pasteurellosis, they were randomly assigned to 1 of 6 groups (n = 12/group). Calves in each group were treated with 10% difloxacin (2.5 or 5 mg/kg of body weight), 5% difloxacin (2.5 or 5 mg/kg), enrofloxacin (5 mg/kg), or saline (0.9% NaCl) solution (control group), once daily for 5 days, and clinical signs were scored daily. On day 15, calves were euthanatized, and the percentage of diseased lung tissue was calculated. Swab specimens of the lungs were submitted for bacterial culture. RESULTS: Mortality rate and percentage of diseased lung tissue were significantly higher and cure rate and average daily gain were significantly lower for control calves, compared with calves in the treatment groups; however, no significant differences were found among treatment groups. Mannheimia haemolytica was isolated from the lungs of 10 control calves and from at least 2 calves in each of the treatment groups. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that difloxacin and enrofloxacin were equally effective for treatment of calves with experimentally induced pneumonic pasteurellosis. However, treatment of infected calves with difloxacin or enrofloxacin may not eliminate the organism.     

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.     

Effect of ivermectin on performance of beef cattle on Georgia pastures

A total of 469 cows and calves from 2 herds, each on 6 pastures, was used to evaluate the anthelmintic efficacy and animal-performance benefits of ivermectin given subcutaneously at a dosage of 200 micrograms/kg to nursing beef calves and their dams during a grazing season. Pastures were paired across the 2 herds. Three pasture groups from 1 herd were randomly assigned to either a nonmedicated control or to a medicated group. Treatment assignments were reversed in the other herd. The control groups comprised 110 cows and 108 calves, whereas 127 cows and 124 calves were treated with ivermectin (200 micrograms/kg). The cows were treated once, in late spring, and the calves were treated twice, once in late spring and again in midsummer. Cattle from one herd were weighed on days - 12, 21, 49, 77 (day of 2nd treatment for calves), and 105, and the other herd was weighed on days - 6, 23, 57, 86 (day of 2nd treatment for calves), and 113. Rectal fecal samples for nematode egg counts were obtained from approximately 25% of the cattle in each pasture on weighing days; usually, the same cattle were sampled each time. Calves treated with ivermectin gained (P less than 0.05) more weight than control calves up to the 2nd treatment date and up to the termination of the study. There was no significant difference between treated and control cows, with regard to weight gain over either interval. Treated calves had fewer positive fecal egg counts (P less than 0.01) and passed fewer eggs (P less than 0.05) after both treatments than did control calves. There were no differences in either number of eggs or number of negative cows between treatment groups. Adverse reactions attributable to treatment were not seen.