title: Epidemiology of large colon volvulus
Creators: name: Suthers, Joanna
Publisher: name: University of Liverpool Repository
Year: 2013

description: Colic is a major cause of mortality in the horse. It is most commonly related to gastrointestinal pathology and has significant economic and welfare implications. Large colon volvulus (LCV) is a painful and rapidly fatal form of colic and in some hospital populations represents between 10 and 20% of horses with colic that undergo exploratory laparotomy. There is a paucity of information on survival following LCV and on risk factors associated with the occurrence of LCV. The aims of this thesis were firstly to describe the long-term survival of horses with LCV and to identify factors associated with survival, and secondly to determine risk factors for development of LCV. The first study presented in Chapter Two utilised clinical data and long-term follow up information from horses with LCV undergoing general anaesthesia at a UK equine hospital over a ten-year period. The study population comprised 116 horses. Of these, 77% survived general anaesthesia. Of the horses that survived anaesthesia, the percentage that survived to discharge, to one year, and to two years was 70.7%, 48.3% and 33.7% respectively. Median survival time of horses that survived general anaesthesia was 365 days. Survival time was negatively associated with higher pre-operative packed cell volume, colon serosal colour, increasing heart rate at 48 hours post-operatively, and evidence of colic during post-operative hospitalisation. Chapter Three presents the results of a prospective case-control study, which aimed to identify horse- and management-level risk factors associated with LCV. Cases were recruited from 4 clinics in the UK and controls were randomly selected from the client population of these clinics over a 24-month period. Multivariable logistic regression was used to investigate variables associated with increased risk of LCV. Increasing height, multiple colic episodes in the previous 12 months and mares, with a greater odds ratio in mares that had previously foaled, were found to increase the risk of LCV. Receiving medication, (excluding anthelmintic treatment) in the previous 7 days, and quidding behavior were also associated with increased risk. Management-level variables associated with greater risk of LCV were an increase in the hours of stabling in the previous 14 days, an increasing number of horses on the premises, and 3 or more people involved in the horse’s care. Nutritional variables associated with increased risk were being fed hay, being fed sugar-beet, a change in pasture in the previous 28 days, and an alteration in the amount of forage fed in the last 7 days. In conclusion, the studies within this thesis have improved our ability to prognosticate survival in horses with LCV and allowed us to identify individuals at increased risk of this disease. Importantly, the work has also identified a number of management practices, which might be modified, in an attempt to reduce the incidence of LCV. This thesis has highlighted several areas that merit on-going research, and which may, in the future, further contribute to our understanding of the disease. This research is relevant to clinicians and horse owners, particularly owners whose horses undergo surgery to correct a LCV, or owners whose horses’ are at increased risk of LCV, such as owners of horses that have suffered previous colic episodes or stud-farm managers.