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Biomedical subjects

E T Lyons

Publications and source records attributed to E T Lyons.

At least 109 records · Page 6Linked to original sources
PubMed1981

Efficacy of levamisole against abomasal nematodes and lungworms in dairy calves: preliminary tests indicating reduced activity for Ostertagia ostertagi.

Dairy calves (n = 18) were used in controlled tests to evaluate activity of levamisole against abomasal nematodes and lungworms. Two formulations of levamisole, injectable (experiment A) and bolus (experiment B), were given in single doses at rates of 6 mg/kg of body weight and 5.4 to 10.2 mg/kg (5.4, 7.6, 8.0, 8.8, or 10.2 mg/kg), respectively. Experiment A included 4 treated and 4 nontreated calves and experiment B consisted of 5 treated and 5 nontreated calves. Aggregate removals of Ostertagia spp (4th stage), Ostertagi (adult), Trichostrongylus spp (4th stage), and T axei (adult) were 0%, 54%, 86%, and 95%, respectively, for injectable treated calves and were 0%, 23%, no data, and 85%, respectively, for bolus-treated calves. Haemonchus spp, present in small numbers, were completely removed from treated calves in experiment A. Several possible explanations are discussed regarding poor removal activity of levamisole by both formulations against O ostertagi. Removal activity was 95% and 100% against Dictyocaulus viviparus for injectable-treated and bolus-treated calves, respectively.

Abomasum↗
PubMed1981

Haloxon: critical tests of antiparasitic activity in equids.

Critical tests were conducted in 14 naturally infected equids (13 horses and 1 pony) to evaluate the antiparasitic activity of haloxon. Single doses were administered by stomach tube to 3 horses and 1 pony (60 mg/kg of body weight), by addition to the feed of 3 horses (60 mg/kg), and intraorally by powder gun to 7 horses (65 mg/kg). Haloxon was efficacious (99% to 100%) against infections of Parascaris equorum, Oxyuris equi (mature and immature), and Strongylus vulgaris at both dosage levels. Probstmayria vivipara parasites were removed in 1 horse treated at 60 mg/kg by stomach tube and S equinus was removed (1 specimen) in 1 horse treated at 65 mg/kg with the powder gun. Removal activity against small strongyles varied from 67% to 92%, and averaged 88% in ther aggregate. Removal of S edentatus fluctuated from 2% to 100%, and was 49% in the aggregate. Haloxon was generally ineffective against Gasterophilus intestinalis and G nasalis, except that it seemed active against 2nd instar G intestinalis when administered at the 60 mg/kg dosage rate in feed and at the 65 mg/kg dosage rate by powder gun. The compound was inactive against Trichostrongylus axei, Habronema muscae, Draschia megastoma, Anoplocephala perfoliata, and A magna. Clinical signs of toxicosis were not observed after treatment. Problems were not encountered in administration of haloxon directly into the back of the mouth with the powder gun.

Animals↗
PubMed1981

Tioxidazole: evaluation of antiparasitic activity of a micronized formulation in horses by the critical test method.

Antiparasitic activity of a micronized formulation of the benzothiazole compound, tioxidazole, at the dose rate of 11 mg/kg, was evaluated by the critical test method. Drug was given by stomach to 3 horses and on feed to 3 horses. Excellent removal activity was found for Strongylus vulgaris (100%) in 5 naturally infected horses, S edentatus (91% to 100%) in 5 horses, small strongyles (88% to 99%) in 6 horses, immature Oxyuris equi (100%) in 5 horses, and Parascaris equorum (100%) in 5 horses (a 6th horse had 10 small specimens present at necropsy). There was no measurable activity against bots, tapeworms, or stomach worms. Tioxidazole, administered in the feed, was palatable. Signs of toxicosis were not observed.

Animals↗
PubMed1980

Variable activity of disophenol against hookworms and lice of northern fur seal pups on St. Paul Island, Alaska.

Six critical tests with disophenol were conducted in July, 1978, in fur seal pups (Callorhinus ursinus) naturally-infected with adult hookworms, Uncinaria lucasi, and infested with various stages of two species of sucking lice, Proechinopthirus fluctus (Ferris) and Antarctophthirus callorhini (Osborn). Disophenol at a dose rate of 12.5 mg/kg was administered subcutaneously to each of six pups. Each pup was contained in an individual cage for 60 h posttreatment at which time pups were exmained at necropsy. Efficacy against hookworms ranged from 2% to 88% and of both species of lice ranged from 26% to 90% for the six pups. Disophenol removed approximately 90% of all adult lice but only slightly more than 60% of all nymphs. The only sign of toxicosis was a probable drug related fluid-like feces for four pups from 12 to 60 h posttreatment.

Alaska↗
PubMed1980

Antiparasitic activity of parbendazole in critical tests in horses.

Critical tests were conducted in 11 naturally infected horses to evaluate the anthelmintic activity of parbendazole. Single doses at the rates of 30, 20, 10, 5, or 2.5 mg/kg of body weight were administered by stomach tube to 1, 4, 2, 2, and 2 horses, respectively. Parbendazole was active against Parascaris equorum, Oxyuris equi, Strongylus vulgaris, Strongylus edentatus, and small strongyles throughout the range of doses. Generally, small numbers of P equorum were present, but apparently a dose rate higher than 2.5 mg/kg is necessary for complete clearance. Removal of O equi was virtually 100%, even at the 2.5 mg/kg dose rate, although mature forms were present in small numbers. Removal of S vulgaris and S edentatus was 98% to 100% at the largest and smallest dose rates and was somewhat inconsistent, especially of S edentatus, at most intermediate dose rates. Overall removal of small strongyles was good even at smallest dose rate. Activity was limited or lacking against stomach parasites. Transient diarrhea was observed for 24 to 48 hours after treatment at each dose rate tested.

Animals↗
PubMed1980

Critical tests of new benzothiazole anthelmintic tioxidazole in the horse.

The basic-dose confirmation tests of tioxidazole for removal of susceptible populations of gastrointestinal parasites of the horse were made in 10 naturally infected horses, using the critical test method (experiment A). A single dose of toxidazole, given at the rate of 11 mg/kg of body weight, was administered to 5 horses by stomach tube and to 5 horses by mixing the drug with the daily grain ration. In the 5 horses given the drug by stomach tube, aggregate average removals were 90% or more for 5 horses infected with Stronglyus vulgaris, 5 infected with S edentatus, 5 infected with small strongyles, 3 infected with Parascaris equorum, 3 infected with mature Oxyuris equi, and 5 infected with immature O equi. Bots (Gastrophilus intestinalis and G nasalis) in 5 infected horses and tapeworms (Anoplocephala perfoliata or A magna) in 3 infected horses were not removed. Activity against stomach worms (Trichostrongylus axei, Habronema muscae, and Drashia megastoma) was not evidenced. In the 5 horses given the drug in the feed, aggregate average removals were 90% or more for 5 horses infected with S vulgaris, 5 infected with S edentatus, 1 infected with S equinus, 5 infected with small strongyles, 3 infected with P equorum, 3 infected with mature O equi, and 5 infected with immature O equi. Activity against bots, tapeworms, and stomach worms was not detected. Larval count data on fecal samples also indicated liited, if any, activity against Strongyloides westeri by tioxidazole at this dosage (11 mg/kg). In addition to experiment A, tioxidazole (11 mg/kg) was administered via stomach tube in a single dose in a critical test to a foal naturally infected with benzimidazole-resistant small strongyles (population B) and removal was only 27% (experiment B). The same 5 species of small strongyles refractory to the benzimidazoles also exhibited resistance to tioxidazole. Specimens of P equorum and S vulgaris were all removed from the foal. Untoward effects of tioxidazole treatment (11 mg/kg) were not observed in any of the animals.

Animals↗
PubMed1979

Critical tests and clinical trials on oxibendazole in horses with special reference to removal of Parascaris equorum.

The efficacy of oxibendazole given at dose level of 10 mg/kg of body weight was determined by 10 critical tests in foals and by 2 clinical trials in 20 foals (16 treated, 4 nontreated), with special interest in the drug activity against Parascaris equorum. The drug was uniformly efficacious (100%) against P equorum in the 10 critical-test foals, each having between 22 and 236 ascarids. Posttreatment reductions of ascarid egg counts in fecal samples were also 100% in suckling foals treated with oxibendazole given as a drench. Ascarid eggs did not reappear in fecal samples until the 8th week after foals were treated. A paste formulation of oxibendazole at 10 mg/kg also eliminated ascarid eggs from feces of 12 suckling foals. Strongyle EPG were markedly reduced by oxibendazole in the 10 critical-test foals and in 16 treated sucklings in the clinical trials. Egg and larval count data on foals in both the critical tests and the clinical trials also indicated oxibendazole was active against Strongyloides westeri. Untoward effects of treatment with oxibendazole were not observed.

Animals↗
PubMed1979

Benzimidazole resistance of equine stronygles--critical tests of six compounds against population B.

Critical tests were conducted on eight horses naturally infected with several species of large and small strongyles from population B. Tested were six benzimidazoles, including thiabendazole (2 lots) (44 mg/kg of body weight); mebendazole (8.8 mg/kg); cambendazole (two formulations) (20 mg/kg); fenbendazole (10 mg/kg); oxibendazole (10 mg/kg); and oxfendazole (10 mg/kg). All compounds were administered by stomach tube except one of the two cambendazole formulations which was an intraoral paste. Removal of large strongyles (when present), Strongylus vulgaris and Strongylus edentatus, was 100% by each drug. In general, five species of small strongyles (Cyathostomum catinatum, Cyathostomum coronatum, Cylicocyclus nassatus, Cylicostephanus goldi, and Cylicostephanus longibursatus) exhibited varying degrees of resistance (% removal) to all of the drugs except oxibendazole. A total of 19 other species of small strongyles from seven genera, including the three described earlier were about 100% removed by the six benzimidazoles. Poor removal of immature (fourth-stage larvae) forms was also characteristic of the six drugs.

Animals↗
PubMed1978

Activities of dichlorvos or disophenol against the hookworm (Uncinaria lucasi) and sucking lice of northern fur seal pups (Callorhinus ursinus) on St. Paul Island, Alaska.

One controlled and six critical tests were conducted in July, 1977 with northern fur seal pups (Callorhinus ursinus) to determine the efficacies of a single dose of dichlorvos capsules at 29.3 to 32.8 mg/kg, tablets at 10.5 to 11.5 mg/kg, or disophenol at 9.9 mg/kg given subcutaneously against natural infections of adult Uncinaria lucasi. In the controlled test, 20 pups were treated and 10 pups were nontreated. Removal of hookworms in this test was 99% for five pups receiving dichlorvos capsules, 99% for five pups receiving dichlorvos tablets, and 77% for 10 pups receiving disophenol. Also, both formulations of dichlorvos and the formulation of disophenol were highly active against natural infestations of two species of sucking lice (Proechinophthirus fluctus and Antarctopthirus callorhini). In critical tests with four pups treated with dichlorvos capsules at 28.6 to 30.6 mg/kg, removal of hookworms was uniformly 100%. Disophenol at 9.9 mg/kg removed 100% and less than 1% of hookworms in two pups, respectively, in critical tests.

Alaska↗
PubMed1978

Observations on the infectivity of parasitic third-stage larvae of Uncinaria lucasi Stiles 1901 (Nematoda: Ancylostomatidae) of Northern fur seals, Callorhinus ursinus Linn., on St. Paul Island, Alaska.

Twelve fur seal pups, which had not nursed their mothers, were used in an infectivity experiment. Pups were exposed to parasitic 3rd-stage larvae of Uncinaria lucasi from belly tissues of fur seal bulls, bachelors, and pregnant cows, to determine maturation capability of the larvae. Hookworms were not recovered from the intestines of 3 pups receiving larvae from belly blubber of bulls, 6 pups receiving larvae from belly blubber of bachelors, and 1 nonexposed pup. Maturation of hookworms did occur in 2 pups exposed to larvae from a mixture of belly blubber, mammary tissue, and milk of pregnant cows. Parasitic 3rd-stage hookworm larvae from belly tissues of pregnant and "non-pregnant" fur seal cows averaged 938.1 and 802.1 micron long, and 34.1 and 31.5 micron wide, respectively; however, larvae from belly tissues of a fur seal bull, bachelors, 2-year-old males, male and female yearlings and pups, and Steller Sea Lion subadults averaged 640.5-732.0 micron long and 20.9-24.9 micron wide.

Abdominal Muscles↗
PubMed1978

Critical tests of the anthelmintic febantel in the horse: activity of a paste formulation alone or with a trichlorfon paste.

Critical tests were carried out in 10 horses to evaluate the antiparasitic activity of febantel given alone or with trichlorfon. Paste formulations were administered intraorally at dose levels of 6 mg of febantel (active ingredient)/kg and 35 mg of trichlorfon (active ingredient)/kg. In 5 tests with febantel alone, removal of 100% was recorded for mature or immature Parascaris equorum from 2 infected horses. Strongylus vulgaris from 4 infected horses, S edentatus from 5 infected horses, and mature Oxyuris equi from 1 infected horse; and removal of 96% was recorded for small strogyles from 1 horse tested, and bots in 5 infected horses were not affected. In 5 horses treated with both compounds, removal of 100% was recorded for mature P equorum from 2 infected horses, immature P equorum from 1 infected horse, S vulgaris from 5 infected horses, Sedentatus from 5 infected horses, mature O equi from 2 infected horses, immature O equi from 1 horse tested, 2nd Gasterophilus intestin-equi from 1 infected horse, 2nd-instar C nasalis from 1 infected horse, and 3rd-instar C nasalis from 4 infected horses. Removal of 98% was recorded for small strongyles from 1 horse tested, and removal of 65% to 100% for 3rd-instar C intestinalis from 5 infected horses. In the aggregate, removal of 3rd-instar C intestinalis was 99%. Untoward effects of treatment were quite limited. Only a transient softening of feces in 1 of 5 horses given the trichlorfon paste plus the febantel paste was recorded.

Acetanilides↗