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Biomedical subjects

J Armour

Publications and source records attributed to J Armour.

At least 91 records · Page 5Linked to original sources
PubMed1980

Anthelmintic efficiency of ivermectin against naturally acquired bovine gastrointestinal nematodes.

Ivermectin, one of the new avermectin group of anthelmintics, was more than 99 per cent effective in removing all stages of Ostertagia ostertagi including inhibited larvae, and adult Trichostrongylus axei when administered to cattle orally at 100 microgram/kg body-weight or subcutaneously at 100 and 200 microgram/kg body-weight. High efficacy (> 98.6 per cent) was also obtained against adults and inhibited larvae of Cooperia oncophora at 100 microgram/kg orally or 200 microgram/kg by subcutaneous injection. The latter treatment caused an 82.3 per cent reduction of adult Nematodirus helvetianus.

Administration, Oral↗
PubMed1980

Failure to protect calves against Taenia saginata using antigens prepared from in vitro cultivation of the larval stage.

Calves were vaccinated intramuscularly against the tapeworm Taenia saginata using excretory/secretory (ES) antigens from short and long term periods of in vitro cultivation of the larval stage of the parasite, four weeks before challenge with 5000 T saginata onchospheres. Neither immunisation regime employed afforded significant protection against challenge. It was considered that this may have been due to a reduction in concentration of, or detrimental effects to, potential immunogens during vaccine production. Elucidation of the nature of the protective ES antigens necessary for standardization of the technique has yet to be achieved in helminths.

Animals↗
PubMed1979

Observations on ostertagiasis in young cattle over two grazing seasons with special reference to plasma pepsinogen levels.

The epidemiology of ostertagiasis in south west Scotland was studied in groups of cattle grazed through two successive grazing seasons separated by a period of winter housing. Towards the end of the first grazing season (September) the numbers of infective larvae (L3) on the pasture had increased to high levels (up to 24,000 L3 per kg) which resulted in high faecal egg counts, worm burdens, plasma pepsinogen levels and the occurrence of clinical ostertagiasis in the calves. By late spring (May) at the onset of the second grazing season, there was an almost complete mortality of the overwintered L3 on the pasture followed by the appearance of moderately high numbers of a new population of L3 in September (up to 9000 L3 per kg). The latter increase in the numbers of L3 was reflected by negligible faecal egg counts, low worm burdens and a moderate elevation of plasma pepsinogens in the second year animals. It therefore seems that although young cattle acquire a good immunity to Ostertagia ostertagi after one season at grass the small infections established in the early part of the second season are capable of contaminating the pasture to levels which could be dangerous for susceptible stock. An allergic reaction in the abomasal mucosa could be the basis of the elevated pepsinogens present in the second year animals.

Animals↗
PubMed1979

A prediction model for bovine ostertagiasis.

A mathematical model based on development and mortality rates, and incorporating data on the infectivity, fecundity and migratory behaviour of Ostertagia ostertagi, was used to predict the level of pasture contamination and the occurrence of clinical ostertagiasis in grazing calves during 1975 and 1976. A comparison of the predicted and observed events showed a good correlation.

Animals↗
PubMed1979

Bovine ostertagiasis: a changing epidemiological pattern?

An unusual epidemiological pattern in bovine ostertagiasis is described in which clinical ostertagiasis occurred in calves grazed on a silage aftermath from late July. The calves were treated with the anthelmintic levamisole prior to grazing the aftermath and the latter had not been grazed since the previous autumn. Analysis of the herbage larval counts suggests that delayed emergence of overwintered Ostertagia ostertagi L3 from the soil was the most likely source of the infection.

Animals↗
PubMed1979

Studies on the epidemiology of bovine parasitic bronchitis.

In the West of Scotland the epidemiology of parasitic bronchitis in grazing calves was studied over a two year period with the aid of tracer calves and herbage examinations for Dictyocaulus viviparus larvae. The observations of both years emphasised the importance of overwintered lungworm larvae as a source of disease. In the first year it was shown that the ingestion and development of these overwintered larvae were, by themselves, directly responsible for severe morbidity, high faecal larval counts and deaths. In the second year it was shown that pasture ungrazed during the winter and spring and from which a hay crop was removed in mid-summer was still capable of producing clinical parasitic bronchitis in susceptible calves within three to four weeks of their introduction in later summer. In both years there was some evidence that the outbreaks appeared to be associated with the sudden availability of infective larvae on the herbage. The possibility that such larvae may have survived for many months in the soil is discussed. Despite the heavy challenge with lungworm larvae experienced by the grazing calves in the first year those vaccinated with lungworm vaccine survived, their clinical signs were mild and of short duration and their faecal larval output was greatly reduced.

Animals↗
PubMed1978

An economic appraisal of helminth parasites in sheep.

The economic effects of the common helminth parasites of sheep are described and the current methods of prophylaxis adopted by sheep farmers in the United Kingdom reviewed. More efficient prophylactic programmes are outlined and the economic benefit accruing from two programmes designed to control fascioliasis and parasitic gastroenteritis are presented in detail.

Animals↗
PubMed1976

Type II ostertagiasis in adult cattle.

During the spring of 1975 outbreaks of ostertagiasis affecting adult cattle were recorded from several beef herds. Two of these outbreaks, one involving an autumn calving herd and the other spring calving, were investigated in detail. The clinical, biochemical, haematological, parasitological and pathological findings are described and were similar to those characteristic of type II ostertagiasis in immature cattle.

Animals↗