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Biomedical subjects

E T Lyons

Publications and source records attributed to E T Lyons.

At least 91 records · Page 5Linked to original sources
PubMed1983

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.

Animals↗
PubMed1983

Cambendazole for strongyle control in a pony band: selection of a drug-resistant population of small strongyles and teratologic implications.

Cambendazole (CBZ) treatments (20 mg/kg) given at 8-week intervals were used for parasite control in a breeding band of ponies (n = 33 to 43) during the period July 1974 to August 1978. Pre- and posttreatment worm egg counts on feces were used to evaluate efficacy of treatments after every 2nd treatment interval by monitoring changes in strongyle egg counts. Initially, effective reductions (expressed as 92% to 96% fewer worm eggs) were lessened to 70% by the 9th treatment (18 months) and to 28% by the 12th treatment, and thereafter, they fluctuated between 0% and 38%. Critical tests on animals culled during the 3rd year revealed that (i) large strongyles (Strongylus vulgaris and S edentatus) were efficaciously removed, (ii) 5 species of small strongyles (Cyathostomum catinatus, Cyathostomum coronatum, Cylicocyclus nassatus, Cylicostephanus longibursatus, and Cylicostephanus minutus) exhibited some degree of resistance, and (iii) 11 species of small strongyles from 6 genera, including the 3 already named, were highly susceptible. Cylicostephanus minutus, in this population exhibited benzimidazole resistance for the first time, whereas Cylicostephanus goldi, previously recognized as resistant in other populations (B and C) in Kentucky, was susceptible to CBZ. A 2-fold increase in the drug-dose rate did not increase efficacy against the CBZ-resistant species of small strongyles, but a 4-fold increase small stronglyles, efficaciously removed 93% of the resistant small strongyles. Foaling rates in the brood band ranged between 38% and 61% for the 5 seasons. Three deformed foals occurred--1 in 1976 and 2 in 1977--among the total of 83 births. Present data did not evidence a probable week of early gestation for possible insult of the fetus by CBZ treatment.

Abnormalities, Drug-Induced↗
PubMed1983

Parasites in Kentucky Thoroughbreds at necropsy: emphasis on stomach worms and tapeworms.

A total of 363 Thoroughbreds (62 males, 292 females, and 9 geldings), 1 to 26 years of age, were examined at necropsy for internal parasites for about a 12-month period from February 1981 through February 1982. Emphasis was on examining the stomach for nematodes and the small intestine and cecum for tapeworms. Parasites recovered from the stomach and infection rates were: Habronema spp--immature (24%), H muscae--adult (38%), Draschia megastoma--immature (13%), D megastoma--adult (62%), and Trichostrongylus axei--adult (4%); lesions caused by D megastoma were found upon gross observation in 58% of the stomachs. The tapeworm, Anoplocephala perfoliata, was recovered from 54% of the horses; A magna was not found. There was no obvious difference in infection rates of the stomach worms and tapeworms according to age or sex of the horses. Seasonal differences were apparent only for immature Habronema spp and immature D megastoma for which infection rates began increasing in June, peaking in October, and declining thereafter. Presence of 4 additional species of parasites was recorded, but only a cursory examination was made for them. These were the large strongyles, Strongylus vulgaris, S edentatus, and S equinus, from the cecum and a filariid, Setaria spp (probably S equina), from the abdominal cavity, for which recovery rates from the horses were 8%, 8%, 1%, and 7%, respectively.

Animals↗
PubMed1982

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.

Animal Feed↗
PubMed1982

Ivermectin: activity against larval Strongylus vulgaris and adult Trichostrongylus axei in experimental infections in ponies.

Activity of ivermectin, administered IM at the dosage rate of 200 micrograms/kg of body weight, was evaluated in controlled tests against migrating larvae of Strongylus vulgaris and adult Trichostrongylus axei in experimental infections in 6 ponies raised worm-free. Ponies were given 2,190 or 2,400 infective 3rd-stage larvae of S vulgaris at 7 days before treatment and 22,000 or 22,750 infective 3rd-stage larvae of T axei at 42 or 45 days before treatment. Three ponies were given ivermectin plus vehicle, and 3 ponies were given the vehicle only; the ponies were euthanatized 7 or 9 days after treatment. At necropsy, 4th-stage S vulgaris larvae were not recovered from visceral arteries of the 3 ivermectin plus vehicle-treated ponies, but 21 to 40 larvae were recovered from each of the 3 vehicle-treated ponies. Also at necropsy, adult T axei (140 specimens) were recovered from only 1 ot the 3 ivermectin plus vehicle-treated ponies, but 4,610 to 6,410 specimens were found in each of the 3 vehicle-treated ponies. Toxicosis was not observed after treatment.

Animals↗
PubMed1982

Controlled tests of pastes of dichlorvos and thiabendazole against induced Strongyloides westeri infections in pony foals in 1973-1974.

In 1973-1974, 4 controlled tests were performed in pony foals (n = 17) raised parasite-free and experimentally infected with Strongyloides westeri. Administration of infective larvae by stomach tube in 1 test resulted in low-grade infections and tended to invalidate the test. Intraoral and percutaneous (intra-aural) administration of larvae resulted in suitable test infections for 1 and 2 tests, respectively. A paste formulation of dichlorvos at 36.3 mg/kg of body weight removal from 4 ponies. Treatment of 4 the dosage rate of 44 mg/kg was consistently effective (greater than 99% to 100%) for eliminating intestinal infections of S westeri.

Animals↗
PubMed1981

Prevalence of Strongylus vulgaris and Parascaris equorum in Kentucky thoroughbreds at necropsy.

At necropsy of 49 Thoroughbreds from farms with generally good parasite control programs in central Kentucky, examination was specifically made for presence of Strongylus vulgaris in all of the horses and of Parascaris equorum in 21 of them. None of the deaths of the horses was caused by infections of internal parasites. Visceral arteries were examined for specimens of S vulgaris and lesions related to migrating stages of this parasite. Contents of the small intestines were examined for P equorum. Specimens of S vulgaris were recovered from 19 (39%) horses, and arterial lesions were observed in 24 (49%) of them. Parascaris equorum was found in 9 (43%) horses. Both parasites were found to persist in generally low numbers on farms in spite of their parasite control programs applied in recent years.

Animals↗
PubMed1981

Overwintering of larvae of the cattle lungworm (Dictyocaulus viviparus) on pasture in Kentucky.

Seventeen dairy calves, raised lungworm-free, were used in an experiment to determine whether lungworm (Dictyocaulus viviparus) larvae survived on a pasture in central Kentucky during the winter of 1979/1980. On Apr 22, 1980, the calves were placed on pasture. Three calves were put on pasture A, on which no cattle had grazed for over 20 years. Fourteen calves were put on pasture B, which had been vacant since Dec 12, 1979 (132 days before beginning of experiment), when several lungworm-infected calves had been removed from the pasture. Fecal samples from the 17 calves were examined for lungworm larvae at weekly intervals for about 6 weeks; lungworm larvae were not found in any of the 3 calves on pasture A, but were found in 12 of 14 (86%) calves on pasture B. One calf from pasture A and 3 calves from pasture B were euthanatized 37 days after being placed on pasture; lungworms were recovered from 1 calf from pasture B.

Animals↗
PubMed1981

Ivermectin: controlled test of anthelmintic activity in dairy calves with emphasis on Dictyocaulus viviparus.

Twelve dairy calves, naturally infected with lungworms and gastrointestinal parasites, were selected for a controlled test with single doses of ivermectin, administered subcutaneously, at the dose rate of 200 micrograms/kg. Specific interest was on efficacy of ivermectin against lungworms (Dictyocaulus viviparus), with ancillary interest directed on abomasal parasites. Ivermectin was administered to 6 calves, and the vehicle only, to 6 calves. At necropsy, 7 days after treatment, lungworms were not recovered from any of the treated calves; nontreated calves, given the vehicle only, were infected with 1 to 46 lungworms each. Removal efficacy against adult Ostertagia ostertagi was 99%. Fourth-stage Ostertagia spp and Trichostrongylus spp and mature Trichostrongylus axei, present in low numbers, were all removed. The fecal egg count for gastrointestinal parasites indicated all eggs, except for a few Nematodirus eggs, were cleared from treated calves. One treated calf showed signs of irritation of the neck at injection site for a short time after treatment and 1 treated calf had a slight indurated area at injection site at necropsy.

Abomasum↗
PubMed1981

Reduced activity of levamisole against Ostertagia ostertagi in dairy calves.

Levamisole bolus formulation was administered in single doses, at rates of 5.8 to 8.1 mg/kg body weight, in 3 controlled tests in male dairy calves (n = 22) in Kentucky. Removals of natural infections of adult Ostertagia ostertagi were 70% and 76% for calves from a hear with a history of regular treatments with levamisole and 85% for calves from a herd receiving levamisole occasionally. Activity against other abomasal nematodes and lungworms was also evaluated.

Animals↗
PubMed1981

Apparent inactivity of several antiparasitic compounds against the eyeworm Thelazia lacrymalis in equids.

Activity of 15 compounds, given alone or in mixtures [butamisole, cambendazole, caviphos, febantel (alone or with trichlorfon), fenbendazole, ivermectin, levamisole-piperazine, oxfendazole, oxibendazole, pyrantel pamoate (alone or with piperazine-carbon disulfide complex), thiabendazole (alone or with piperazine or with trichlorfon), tioxidazole, and trichlorfon], against Thelazia lacrymalis was evaluated in 102 equids. Determination of activity was based on comparison of infection rate in treated animals examined at necropsy with infection rate of dead equids in our contemporary surveys. None of the compounds appeared to be active against T lacrymalis.

Animals↗