Efficacy of a morantel sustained-release bolus for the control of gastrointestinal nematodes in Florida dairy heifers.

The effectiveness of a morantel sustained-release bolus (MSRB) in controlling gastrointestinal nematode infections was determined in 70 Holstein heifer calves with no prior grazing experience. Calves were allotted to 2 treatment groups and were maintained in Florida during the grazing season on divided pastures of equal area. One MSRB was administered to each calf in 1 group at the time of turnout onto spring pasture, whereas calves in the other group remained as nonmedicated controls. By the end of the grazing season, treatment resulted in significantly (P less than 0.05) lower worm burdens and significantly improved weight gains. The MSRB-treated calves were able to reach breeding weight 2 to 4 weeks earlier than did nonmedicated calves.

An optimized enzyme-linked immunosorbent assay for quantitative diagnosis of bovine fascioliasis.

An optimized immunoassay for detection of antibody to Fasciola hepatica antigen in cattle was developed through the adaptation of a kinetics-dependent, enzyme-linked immunosorbent assay (k-ELISA) to a microplate format. Enhanced sensitivity and a strict quantitative nature were achieved with the utilization of enzyme kinetics. With this k-ELISA, significant (P less than 0.01) elevations in anti-F. hepatica antibody could be detected as early as 2 wk post-infection in experimentally infected calves. Furthermore, fluke-burden related differences in anti-F. hepatica antibody levels between 3 different levels of fluke infection were evident.

Diagnosis of Fasciola hepatica infection in beef calves by plasma enzyme analysis.

Plasma analysis for albumin, total bilirubin, and total protein values and aspartate aminotransferase (AST), arginase, and gamma-glutamyl transpeptidase (GGT) activities was used for the early and quantitative diagnosis of experimental Fasciola hepatica infections in beef calves. Calves were infected on 3 occasions with 1,000 (n = 5), 100 (n = 5), or 10 (n = 4) metacercariae for a total infective dose of 3,000, 300, or 30, respectively. Albendazole (15 mg/kg of body weight) was administered to 7 infected calves on postinfection (initial) week (PIW) 13. All calves were euthanatized and necropsied on PIW 16 for the determination of fluke infections. Plasma constituents were determined weekly. Significant (P less than 0.05) increases in AST activity occurred as early as PIW 4 and GGT activity at PIW 9, as compared with that in noninfected controls. Fluke burden-related differences were observed in GGT activity from PIW 9 onward. Increases in AST activity reflected parenchymal liver damage, whereas increases in GGT reflected hepatobiliary damage; therefore, differentiation could be made between the migratory and ductal phases of the infection. There was no correlation between arginase activity and fluke infection. As compared with fecal examination results, plasma enzyme analysis gave an earlier and semiquantitative indication of F hepatica infection in experimentally infected calves. Although increases in these plasma constituents were not definitely diagnostic of fascioliasis, useful information on the size of the fluke burden and progress of the disease process could be obtained by these methods. Plasma enzyme analyses of AST and GGT were not indicative of chemotherapeutic success or failure when calves with mature F hepatica (14 weeks old) infections were treated.

Efficacy of a benzenedisulfonamide against experimental Fasciola hepatica infections in calves.

The anthelmintic efficacy of a benzenedisulfonamide was evaluated by administering the drug parenterally at dosage levels of 2, 4, 8, and 16 mg/kg of body weight to crossbred Brahman calves with experimental Fasciola hepatica infections. In the 3-week period after treatment, fluke ova counts of treated calves were markedly reduced from counts obtained just before treatment. At necropsy, the mean fluke recovery for all 4 benzenedisulfonamide dosages were significantly (P less than 0.01) reduced. The efficacy of benzenedisulfonamide against F hepatica at dosage levels of 2, 4, 8, and 16 mg/kg was 97.5%, 99.5%, 100%, and 100%, respectively.

Flubendazole: dose range and efficacy studies against common internal parasites of swine.

The anthelmintic spectrum of activity and efficacy of flubendazole, using pigs naturally infected with helminth parasites, were determined in 4 experiments, using 157 pigs. Flubendazole (1.5 mg/kg of body weight) mixed in feed or top-dressed on feed for 5 consecutive days was highly effective as an anthelmintic. This dosage level indicated 100% efficacy against mature Ascaris suum, Oesophagostomum dentatum, Trichuris suis, and Metastrongylus apri. There was 88% efficacy against Strongyloides ransomi and 85% efficacy against Stephanurus dentatus and immature Ascaris suum. There was some activity against Globocephalus sp and Macracanthorhynchus hirudinaceus, but insufficient numbers of these parasites were present to make an accurate assessment.

Mebendazole paste as an anthelmintic in random source research cats.

Mebendazole paste, administered per os daily for 3 days, at dose levels of 22 mg/kg and 33 mg/kg was highly effective in removing Ancylostoma tubaeforme from naturally infected cats. The 22 mg/kg dose gave the highest efficacy (95.5% critical and 98% controlled). The same product at 11 mg/kg, 22 mg/kg, or 33 mg/kg was 100% effective in removing Toxocara cati from naturally infected cats. Both 11 mg/kg and 22 mg/kg dose levels were highly efficacious against the common tapeworm, Dipylidium caninum. No toxic side effects or clinical illness were observed in any of the cats used in this study.

Fenbendazole as a therapy for naturally acquired Stephanurus dentatus and gastrointestinal nematodes in feral swine.

Adult feral swine, naturally infected with kidney worms (Stephanurus dentatus) and gastrointestinal nematodes, were divided into two groups of 10 pigs each. One group was treated with fenbendazole (Panacur, Hoechst AG, Frankfurt am. Main) mixed in feed at the rate of 3 mg kg-1 body weight for 3 days. The second group received feed only and was designated as non-treated controls. The animals in both groups were necropsied 3 weeks post-treatment and examined for the presence of live and dead adult kidney worms in the perirenal and ureteral area, ureteral penetration, the presence of kidney worm larvae in the liver, hepatic scars due to kidney worm larval migration, and for liver fibrosis. No live adult kidney worms were found in the perirenal and ureteral areas of treated pigs, and the non-treated pigs harbored an average of 42.8 live worms. No liver kidney worm larvae were found in the livers of treated pigs, and the non-treated pigs averaged 6.7 live larvae. At necropsy, urine samples from 8 of the 10 treated pigs contained no kidney worm eggs, and only 2 eggs were found in samples from each of the remaining 2 pigs in this group. In contrast, urine samples from 8 of the non-treated pigs contained numerous kidney worm eggs. Reductions in ascarid (Ascaris suum) and nodular worm (Oesophagostomum dentatum) egg counts were also observed in treated pigs.

Anthelmintic efficacy of albendazole in calves with naturally acquired Fasciola hepatica infections.

The anthelmintic efficacy of albendazole was evaluated as an oral drench at dosages of 15.0, 10.0, and 7.5 mg/kg of body weight in 3 groups crossbred Brahman calves (n = 12 group) infected with Fasciola hepatica. Although posttreatment fluke ova counts for the 3 albendazole treatment groups were significantly (P less than 0.01) lower (av 82%) than were counts in nontreated calves, there were no significant differences in the responses to the different albendazole treatments. At necropsy, adult fluke counts in treated calves were lower (P less than 0.05) than were counts in nontreated calves, but as with ova counts, a dose-related trend was not noticed. Efficacy against adult flukes was 63.4%, 50.0%, and 56.6% for 15.0, 10.0, and 7.5 mg/kg, respectively. Activity against immature flukes was not observed in calves given the 10.0 and 7.5 mg/kg, but there was a 36% decrease of flukes in those calves given 15.0 mg/kg. Significant decreases (P less than 0.05) in fluke ova viability were observed for the 3 treatment groups in which 12.9% of ova collected at necropsy failed to embryonate (control group av 6.7%). Posttreatment weight changes were not significantly different, although gains were greater within albendazole treatment groups. Decreases in gastrointestinal parasite ova counts after treatment were 98%, 93%, and 93% for groups given 15.0, 10.0, and 7.5 mg/kg, respectively. Ova counts in nontreated calves increased 26.2% during the same period.

Effects of injectable famphur on young Brahman and Angus cattle.

Clinical responses were monitored in young Angus and Brahman bulls given IM injections of an experimental solution of 35% famphur in a dose 5 times greater than the recommended dose (83.2 mg/kg). Five of the 6 treated Brahman bulls had severe clinical signs of organophosphorous toxicosis, and 4 died within 48 hours after they were dosed. Only 1 of the 5 treated Angus bulls showed clinical signs of toxicosis and it recovered. In a subsequent trial, clinical and cholinesterase responses were monitored in young Brahman bulls, steers, and heifers given famphur at different dosages. Highly significant (P < 0.001) RBC cholinesterase inhibition over the 28-day trial was observed in animals given 16.6, 33.3, and 49.9 mga of the drug/kg. In comparison to Brahman heifers and steers, a lower treatment level of famphur (33.3 mg/kg) induced toxicosis in bulls. However, no significant differences in RBC or plasma cholinesterase inhibition were found to be due to treatment-sex interactions.

Effects of hexachlorethane on the milk yields of dairy cows in north Florida infected with Fasciola hepatica.

Hexachlorethane was evaluated as a fasciolicide in dairy cattle under field conditions. After treatment with hexachlorethane, Fasciola hepatica-infected cows had a significant (P = 0.05) average daily milk yield increase (90 to 120 days after treatment) of + 4.2 kg/day (+ 5.0 kg/day for single treatment and + 4.0 kg/day for double treatment) over daily yields of the previous lactation. Nontreated controls and noninfected treated animals did not have significant gains over yields of the previous lactation. A 73.0% efficacy was observed against egg production by F hepatica after a single treatment of 90 g of hexachlorethane/animal. After a 2- to 3-month interval, a second treatment produced a combined treatment efficacy against fluke egg production of 91.2%.