Biomedical subjects
K A Linklater
Publications and source records attributed to K A Linklater.
Proposed reorganization of the Veterinary Field Service.
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Dandy-Walker malformation in lambs.
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A field trial of ovine enzootic abortion vaccine.
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Field studies on the efficacy of a long acting preparation of oxytetracycline in controlling outbreaks of enzootic abortion of sheep.
The effects of long acting oxytetracycline in controlling outbreaks of enzootic abortion of ewes were studied over three consecutive years in 13 different commercial flocks. When used in the face of an outbreak the compound produced a statistically significant reduction in abortion in treated ewes when compared to untreated controls. There was, however, only a marginal difference in the overall abortion rate between treated and untreated groups of ewes in known infected flocks, where the drug was used in anticipation of an abortion storm, mainly because the abortion rate was too low in the control group. It is suggested that oxytetracycline therapy should only be used in an effort to control an actual abortion outbreak on the understanding that the treatment will not eradicate infection from the flock.
Salmonellae in sewage sludge and abattoir effluent in south-east Scotland.
A survey into the prevalence of salmonella organisms in sewage in the Borders Region of South-east Scotland is described. A total of 317 isolates representing 34 different serotypes were made, of which only 5 serotypes appeared in animals, supporting the view that the spreading of sewage sludge on to pastureland presents little risk to livestock provided the recommended guidelines are followed. Nevertheless, Salmonella typhimurium phage type 12, identified in sewage, was also recovered from animals in incidents on 11 farms, including 4 which had received sludge from this source. A further 48 isolates (13 serotypes) were obtained from the parallel monitoring of abattoir effluents, indicating that the background level of salmonella infection in the animal population appears to be low in comparison to that in humans.
Outbreak of psoroptic mange in cattle.
A severe outbreak of psoroptic mange in beef cattle is described. Up to half the animals in some groups were extensively affected and debilitated. Performance was poor with days to slaughter weight increased. Ivermectin was the most effective form of treatment. The possible origin of the infestation and the ways of controlling the condition are discussed.
Abortion in sheep associated with Salmonella montevideo infection.
In the eight year period, 1974 to 1981, abortion associated with Salmonella montevideo infection was recorded in 16 flocks in south east Scotland. Two of these flocks experienced infection in each of two years making a total of 18 incidents. Apart from abortion, there was little evidence of ill health in ewes and lambs in affected groups. The number of ewes which aborted in any one flock was very variable. The worst affected had 130 abortions which represented 25 per cent of the animals at risk. On the other hand in 10 of the incidents 6 per cent or less of the pregnant ewes were affected.
Salmonella montevideo infection in sheep and cattle in Scotland, 1970-81.
Outbreaks of abortion associated with infection by Salmonella montevideo have affected sheep in the east, especially the south-east, of Scotland each year since 1972. Disease in the north and north-east was usually less severe. Between 1 January 1970 and 31 December 1981, a total of 67 incidents affecting sheep were reported by veterinary laboratories to the Communicable Diseases (Scotland) Unit, 87% of which presented during the main lambing months of February, March and April. Twenty-one episodes of bovine infection were also recorded over the same period, 17 of which involved single animals only, usually an aborted cow or a scouring calf. Despite intensive investigations, neither the origin nor the mode of spread of S. montevideo infection among sheep and cattle in Scotland have been established with any certainty, although there has been considerable evidence indicating the role of scavenging wild birds, particularly seagulls, as vectors transmitting infection to other farms in the same district. Also largely unexplained are the differences in the epidemiology and clinical pattern of disease in the south-east compared to the north and north-east, while sheep in the west of Scotland have remained virtually unaffected throughout.
Pneumonia in sheep associated with dipping in carbolic dips.
Fourteen outbreaks of pneumonia in sheep following dipping in carbolic dips were investigated at seven laboratories. Deaths commonly occurred between one and three days after dipping and fat young sheep of the Suffolk and Border Leicester breeds were most usually involved in outbreaks. The pneumonia was characterised by hyperaemic, oedematous and cyanotic lungs, and the main histological features were hyperaemia, fluid and cellular exudation into alveolar spaces, and widespread epithelialisation of alveolar walls. The microscopic changes differed from pneumonic pasteurellosis and no significant organisms were recovered from any of the lungs. One of 27 Dorset Horn lambs dipped in a batch of dip which had been incriminated in some episodes developed an epithelialising interstitial pneumonia, while two out of three Suffolk lambs dipped in twice the recommended strength of the same batch of dip became ill with severe pneumonia, apparently following skin absorption.
Condemnation of sheep due to ascariasis.
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The effects of challenge with homologous and heterologous strains of Border disease virus on ewes with previous experience of the disease.
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Field studies on enzootic abortion of ewes in south east Scotland.
Statistical data were collected from 20 sheep flocks in which enzootic abortion of ewes (EAE) was diagnosed by examination of fetal material and maternal blood samples. The abortion rate in the 10,645 ewes in these flocks was 7.6 per cent. Thirteen of the flocks were fully vaccinated against EAE but the abortion rate in these was still in the order of 6.5 per cent. EAE was the major cause of the problem as ascertained from the laboratory examination of samples from a wide range of cases of abortion. There is therefore evidence that, in some flocks in south east Scotland, the efficacy of the vaccine against EAE is unsatisfactory. The reasons for this are discussed.
Problems in the diagnosis of acute coenurosis in sheep.
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Spontaneous renal disease resembling hyperoxaluria in young lambs.
Five out of 60 purebred Suffolk lambs died when four to six weeks old with a nephrosis characterised by heavy deposits of crystals resembling calcium oxalate in the tubules. The source of oxalate was not clearly identified but may have resulted from oxalate-forming mould contamination of concentrates fed to both ewes and lambs.