Horserace Betting Levy Board Research Articles

Changes in the equine EEG during surgery: The effect of an intravenous infusion of thiopentone

Spontaneous EEG changes during castration have been identified in horses anaesthetized with halothane ( Murrell et al. 1999). This study, using the same model, investigated the effect of thiopentone on the response of the equine EEG to surgical stimulation. Six yearling ponies, mean weight 210 ± 36 kg, were studied. Following pre-anaesthetic medication with acetylpromazine, general anaesthesia was induced with guaiphenesin and thiopentone. Anaesthesia was maintained with halothane, F Ehal 1.2%, vaporized in oxygen and an infusion of thiopentone IV. The infusion was started 30 minutes after the induction of anaesthesia to achieve a target plasma concentration of 10 µg ml−1. Ventilation was controlled to maintain normocapnia (PaCO2 was measured by arterial blood gas analysis) and the EEG was recorded continuously. Baseline measurements were recorded over 5 minutes at least 10 minutes after the infusion began but before the start of surgery. Castration was defined as section of the spermatic cord. Six blood samples were taken during the baseline and castration time periods for analysis of serum thiopentone concentration by high performance liquid chromatography. The derived EEG variables median (F50) and spectral edge (F95) frequencies and total power (Atot) were examined. For each horse, the EEG data were averaged to produce a single value for F50, F95 and Atot every 30 seconds. These values, recorded during the five minutes baseline and two castration time periods were compared using repeated measures anova. Data are presented as mean ± SD The mean serum concentration of thiopentone during the infusion (23 ± 10.5 µg ml−1) varied widely between individual animals. The F50 was significantly higher (p = 0.0001) during castration compared to the baseline period [104.4 ± 8.8% (testicle 1); 105.8 ± 13.4% (testicle 2)]. Atot decreased significantly (p < 0.0001) during castration [98.8 ± 4.4% (testicle 1); 93.7 ± 6.5% (testicle 2)]. The measured serum thiopentone concentrations were larger than the target concentration, which made the results more difficult to interpret. The ponies appeared to be divided into two groups. In four animals F50, F95 and Atot changed very little during castration compared to the baseline time period. Three of these animals had the largest serum thiopentone concentrations. In the two other animals F50 increased and Atot decreased, the changes were particularly marked in one animal. These animals had lower serum thiopentone concentrations than the first group. Compared to the previous study ( Murrell et al. 1999), in the two ponies which responded with EEG changes during castration, the decrease in Atot was smaller in magnitude, the increase in F50 was similar. Changes in Atot may indicate changes in the adequacy of anaesthesia ( Hall & Clarke 1991). An infusion of thiopentone IV did not obtund an increase in F50 but minimized changes in adequacy of anaesthesia during castration. These results support an anti-analgesic action of thiopentone on the equine central nervous system ( Hall & Clarke 1991). Acknowledgements: JM is a Horserace Betting Levy Board Scholar.

Extracts from Horserace Betting Levy Board Common Code of Practice for Equine Viral Arteritis

Extracts from Horserace Betting Levy Board Common Code of Practice for Equine Viral Arteritis

The Horserace Betting Levy Board's code of practice for equine viral arteritis for the 1994 breeding season

The Horserace Betting Levy Board formulates codes of practice for the control of contagious equine metritis and other equine bacterial venereal diseases, and equine viral arteritis and equid herpesvirus 1. This year's codes have just been published and the code of practice for EVA, reproduced below, has been substantially amended following the recent outbreak in the UK. The code is intended for use by veterinary surgeons and breeders of thoroughbred and non-thoroughbred horses. The HBLB states that its recommendations represent the minimum measures necessary to monitor for the presence of equine arteritis virus and to prevent its spread when its presence is identified.

Horserace Betting Levy Board Conference

A conference arranged by the Veterinary Advisory Committee of the Horserace Betting Levy Board was held at the Royal Society premises in London on 22 February 1983. The conference was divided into two sections. Part 1 dealt exclusively with recent studies on equine respiratory infections, while in the second part reports of work on a variety of subjects, including immunology, muscle physiology and haemodynamics, were presented.

Contagious equine metritis: the present situation reviewed and a revised code of practice for its control.

This report contains details of the code of practice for the control of contagious equine metritis (CEM) during the 1979 breeding season. It was prepared under the guidance of a scientific committee established by the Horserace Betting Levy Board under the chairmanship of Sir David Evans, FRS. The code is similar to the one introduced for the 1978 breeding season but takes into account the experience gained during the past 12 months. Following discussions with colleagues in Ireland it has been agreed that a similar code of practice will be introduced in the United Kingdom and Ireland so as to facilitate a uniform policy for the control of CEM. A summary of this report will be circulated to thoroughbred mare and stallion owners.

The Equine Skull: Its Radiological Investigation1

Veterinary RadiologyVolume 15, Issue 1 p. 70-78 The Equine Skull: Its Radiological Investigation† Christine Gibbs, Christine Gibbs Department of Veterinary Surgery Langford House, Langford Bristol BS18 7DU, England Lecturer, Department of Veterinary Surgery, University of Bristol, England.Search for more papers by this author Christine Gibbs, Christine Gibbs Department of Veterinary Surgery Langford House, Langford Bristol BS18 7DU, England Lecturer, Department of Veterinary Surgery, University of Bristol, England.Search for more papers by this author First published: January 1974 https://doi.org/10.1111/j.1740-8261.1974.tb00672.xCitations: 13 † This manuscript is based on a paper presented at the third conference of the International Veterinary Radiology Association in Washington, D. C., Sept. 5–7, 1973. Financial support for attending this conference was received from the Horse Race Betting Levy Board. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume15, Issue1January 1974Pages 70-78 RelatedInformation

On the morphology, growth and identification of the pre-infective larvae of some horse strongylids.

Descriptions are given of the first and second-stage larvae of Strongylus edentatus, S. vulgaris, S. equinus and Trichonema nassatum and newly hatched larvae of Trichonema catinatum and Triodontophorus serratus. Information has been obtained on the growth of pre-infective larvae and on the structural changes which occur during the first ecdysis. Most of the species of newly hatched larvae studied can be differentiated on the basis of differences in appearance, dimensions and other morphological features. The advantages of differential diagnosis of horse strongylid infection using first-stage larvae rather than infective larvae are discussed.My thanks are due to Dr H. D. Crofton for his constructive criticism and advice and to Professor H. E. Hinton, F.R.S. for the provision of laboratory facilities.This work would not have been possible without the willing co-operation of Mr L. J. Potter from whose slaughterhouse the parasites were collected. I am also indebted to the Horse Race Betting Levy Board for their financial assistance.

Variations in the fecundity of strongylid worms of the horse.

SUMMARYA large proportion of Strongylus vulgaris, S. edentatus and Trichonema nassatum collected from the gut lumen of slaughtered horses during the winter did not contain eggs. The proportion of Trichonema catinatum without eggs declined to a low level during the winter and rose to relatively high levels during the summer, It has been concluded that worms without eggs are newly matured individuals and that seasonal variations in fecundity reflect similar fluctuations in the age distribution of the adult populations. These fluctuations are related to seasonal differences in the numbers of infective larvae ingested and to the length of parasitic development.Most Strongylus vulgaris, S. edentatus and Trichonema nassatum reach the adult stage during the winter and it has been suggested that an increase in worm numbers during this period is responsible for a rise in the faecal egg counts of horses in the spring. The observations on T. catinatum indicate that the level is maintained by the arrival of new individuals during the summer.I wish to thank Dr H. D. Crofton for his constant advice and encouragement during this work and Professor H. E. Hinton, F.R.S., for the provision of laboratory facilities. I am indebted to Mr L. J. Potter for allowing me to collect the parasites from his slaughterhouse at Bishop Sutton, near Bristol. This work was carried out during a research studentship funded by the Horse Race Betting Levy Board.

Quantitative studies on the kinetics of establishment and expulsion of intestinal nematode populations in susceptible and immune hosts. Nippostrongylus brasiliensis in the rat.

This paper describes the quantitative aspects of establishment and expulsion of Nippostrongylus brasiliensis in the normal and immune rat. It is proposed that this helminth infection may be described in terms of four phases. These are: (1) loss phase 1 (LP1). A proportion of the infecting dose of larvae is immobilized or destroyed before or during the course of migration via the lungs to the intestine. (2) The plateau phase. The worm number remains static in the predilection site. (3) Loss phase 2 (LP2). This is analogous to the self-cure reaction and during this worms are expelled from the host by an immunological mechanism. The onset of the expulsion is sudden and the process is exponential. It continues at a steady rate until a threshold is reached. (4) Threshold phase. A small residual population of worms is not expelled and survives for a fairly prolonged period.The pattern is maintained in immune animals undergoing second or third infections but there are quantitative differences. With increasing number of infections LP1 becomes greater, the plateau phase is shortened and the expulsion rate of LP 2 increases. It is suggested that the rate coefficient of this phase is an accurate measure of the immune status of the animal. The threshold phase is of a similar order in first, second and third infections. These results are discussed with regard to their significance as a measure of the immune status of the host, their implication regarding the mechanism of helminth expulsion and their relevance to other helminth infections.The authors wish to thank the Agricultural Research Council and Allen and Hanburys Ltd. for the financial support which made this work possible. During this period Ellen E. Jarrett held a Horserace Betting Levy Board Scholarship.