In EVJ's last issue, Dr Martin Burton challenged the veterinary world to prepare and publish systematic reviews that will inform veterinary practice [1]. Dr Burton's comments were in response to our publication of our first systematic review addressing interventions for dynamic intermittent dorsal displacement of the soft palate [2]. Clinicians looking for other, similarly robust pieces of evidence in relation to either surgical or medical interventions in the horse are likely to be rather disappointed. Nevertheless, in clinical and applied research relating to colic, numerous groups internationally are working on clinically relevant research questions relating to this major cause of equine mortality. Much early work on colic surgery was published in EVJ by Professor Barrie Edwards and his colleagues, eventually going on to establish a huge database on risk factors and outcome following colic surgery in general [3]. There is now a need to refine our questions about colic more specifically to build up evidence that will influence clinical practice.
What are the risk factors and prevalence of colic for horses in specific subgroups?Parasite infection is recognised as a major risk factor for colic in many age groups and types of horses, and the spectre of multidrug anthelmintic resistance is on our horizon [4,5]. In this issue, Dr Relf and colleagues report that despite awareness of this challenge amongst UK Thoroughbred farm managers and owners, there is now a pressing need to convince them to adopt control strategies that are less dependent on anthelmintics to minimise the development of widespread resistance [6]. Increasing age is significantly associated with colic [7], and geriatric horses are more likely to have more serious forms of colic, which is reflected by increased levels of pain, lack of intestinal borborygmi and abnormal peritoneal fluid when presented to hospital compared with those found in nongeriatric horses [8]. However, the survival of geriatric horses with a strangulating lesion or requiring jejunojejunostomy was not different from that of mature horses with similar lesions, suggesting that age itself did not influence outcome in these conditions. Geriatric horses were, however, less likely to survive surgery for simple obstruction of the large colon, but again this may reflect differences in pathology rather than age per se [9]. Crib-biting has been associated with colonic obstruction [10] and epiploic foramen entrapment [11], while a study in a group of horses with various surgical and medical diagnoses showed that cribbing and windsucking were significantly associated with colic in general but not with any specific form of colic [7]. In the same study, investigators were unable to show any relationship between other repetitive behaviours or an anxious temperament and colic [7]. In this issue, Fielding and others report the results of an investigation of colic in competing endurance horses and examine both causes and outcome [12]. The majority were suffering from ileus or nonspecific colic and...