Equine nutrition in the post‐operative colic: Survey of Diplomates of the American Colleges of Veterinary Internal Medicine and Veterinary Surgeons, and European Colleges of Equine Internal Medicine and Veterinary Surgeons

Abstract Background Evidence is lacking concerning re‐introduction of feed and water following colic surgery. Objectives To describe current approaches of European and American specialists to re‐introduction of feed and water in adult horses following surgical treatment of common intestinal lesions, assuming an uncomplicated recovery. Study design Cross‐sectional survey. Methods Electronic invitations, with a link to the online survey, were sent to 1,430 large animal specialists, including Diplomates of the ECVS, ACVS, ECEIM and ACVIM colleges. Results The response rate was 12.6% including partial respondent data. Responses for each multiple‐choice question were between 123 and 178. Results are expressed as the percentage of the total number of responses and as a range where specific lesions are grouped together. Respondents reported that horses with large intestinal displacements were offered free choice water (63%‐65%) within 3 hours (55%‐63%), whereas horses with a small intestinal strangulating lesion were offered < 2 L water (64%‐74%) 12‐24 hours (28%‐34%) post‐operatively. Horses with a large colon displacement were offered feed within 3 hours of surgery (16%) with the majority offered feed 6‐12 hours (35%‐36%) post‐operatively. Horses with small intestinal strangulating lesions and small colon lesions were offered feed 24‐48 hours (34%‐42%) after surgery. Following small intestinal, small colon or caecal lesions, horses were re‐introduced feed in handfuls (79%‐93%) and initially with grass (41%‐54%). Horses with large colon displacements were mostly fed handfuls (49%‐50%) of forage initially, but a number of respondents would offer larger quantities such as a small bucket (35%‐37%) and predominantly of hay (50%‐51%). Main limitations Low response rate. This study did not take into account common post‐operative complications that may alter the clinical approach. Conclusions This post‐operative colic nutrition survey is the first to describe current clinical practice. Further research is required to investigate nutritional strategies in post‐operative colic cases.


| INTRODUC TI ON
Feeding the post-surgical colic case is predominantly led by clinicians' experience and the lesion(s) identified. There is little published evidence regarding a 'gold standard' approach of what and when to feed, the amount and frequency. This highlights the importance of identifying the degree of variability in clinicians' current approaches to re-introducing feed and water to the adult horse following colic surgery for common intestinal lesions. Although understandably, all cases are treated individually, it would be advantageous to gain information on the general approach for the uncomplicated case. While this would not establish a best practice approach, the information obtained from such descriptive research could provide the stimulus to generating future research with a greater emphasis on evidence-based medicine. 1,2 Firstly, however, an understanding of current practice is needed.
It is probable that many horses in the post-operative period following correction of gastrointestinal disorders would benefit from enteral nutrition (EN), and EN has the most encouraging impact in humans following gastrointestinal surgery. Human randomised control trials and meta-analyses of early EN (<24 hours post-operatively) demonstrate the potential beneficial effects on clinical outcomes including wound healing, anastomotic strength, gastrointestinal function and motility and length of hospital stay. [3][4][5][6][7] Although we cannot directly extrapolate from humans to horses, it is believed that if the gastrointestinal tract is functional then EN should be encouraged. Positive indicators of a functional gastrointestinal system may include stable cardiovascular parameters, defaecation post-operatively, reasonable appetite, good borborygmi, evidence of small intestinal motility or absence of distended, amotile loops of small intestines on ultrasound examination and absence of gastric reflux. 8 The overall objective of this study was to gain an overview of the opinions and practices of European and American equine specialists.
Within the human literature, this is an approach used when there is insufficient data for evidence-based guidelines. 9 This strategy has been adopted in other areas of equine medicine to identify and assess the opinions and practices of specialist clinicians in circumstances where definitive scientific evidence is lacking. This has provided a current international perspective on the views and present practices of equine veterinary specialists. 10,11 The specific aims of this study were 1) to report the different approaches favoured by European and American specialists to re-feeding adult horses following surgical treatment of common intestinal lesions and 2) to identify the lesions that are more likely to undergo later re-introduction of water and feed and return to full feed.

| MATERIAL S AND ME THODS
The electronic questionnaire was created using web-based propri- No reminders were sent to nonresponders.
The questionnaire (Data S1) was designed to enable completion within approximately 10-15 minutes, and consisted of 10 common surgical intestinal lesion scenarios. For each scenario, seven identical questions were asked, both closed-(eg multiple choice with tick boxes) and open-ended (eg allowing comments) questions. This allowed for respondents to skip specific questions if they had not been exposed to a portion of the surgical scenarios contained in the questionnaire. The first two questions were aimed at identifying the timing and quantity of water that is first offered after surgery. The next three questions aimed to identify the timing, type and quantity of feed first offered. The sixth question was aimed at identifying over how many days, once re-feeding had begun, clinicians returned horses to full feed. The final question for each scenario was to ascertain if any supplements would be used (eg electrolytes, prebiotics, probiotics, salt, mineral oil, etc.). At the end of the questionnaire, an open-ended question was asked to ascertain clinicians' approaches following cessation of post-operative reflux (POR) to re-introduction of water and feed.

| Data analysis
Statistical analyses of the online survey results included descriptive analysis of respondent data. The mode was identified and the number of responders choosing that option was expressed as the percentage of the total number of responses and expressed as a range Conclusions: This post-operative colic nutrition survey is the first to describe current clinical practice. Further research is required to investigate nutritional strategies in post-operative colic cases.

K E Y W O R D S
horse, colic, exploratory laparotomy, re-feed, re-water TA B L E 1 A table displaying the raw data of the answers to the first two questions of the survey regarding re-introduction of water: 'When would you offer water following anaesthesia (assuming no reflux)?' and 'Volume of water offered first?'. Answers for all intestinal scenarios are displayed with the number of respondents and in italics are the percentage of respondents

| Respondent data
The response rate was 12.

| Re-introduction of water
Respondents reported that horses with a large intestinal displacement would most commonly be offered free choice water (63%-65%), with introduction of water within 3 hours following recovery from anaesthesia (55%-63%). Respondents would re-introduce water at <3 hours (34%-35%) and as free choice (39%-49%) for large colon torsion, caecal impaction with typhlotomy and small colon lesions. Respondents indicated that cases of caecal impaction with by-pass had water re-introduced at 3-6 hours (30%) and with a volume of <2 L (44%). Horses with a small intestinal strangulating lesion were most commonly re-introduced with <2 L water (64%-74%) and 12-24 hours (28%-34%) after surgery (Table 1).  Figure 1).    respondents indicated that horses with a large colon torsion would be fed handfuls of feed (69%) and predominantly grass (40%), but a large proportion of respondents also fed hay (36%) after surgery (  Figure 3).

| Addition of supplements
Twenty-six per cent of respondents reported using probiotics for ≥360° colon torsions; however, they were used less frequently following other intestinal lesions (13%-22%). Prebiotics were not widely used in any post-operative colic case (2%-4%). Electrolytes were used by responders for 9%-14% of all lesions and salt for 11%-17%. TA B L E 3 A table to display the raw data of the answers to the question 'Once re-feeding has begun, over how many days do you aim for the horse to return to full feeds (assuming no reflux/ complications)?' of the survey regarding re-introduction of feed. Answers for all intestinal scenarios are displayed with the number of respondents and in italics are the percentage of respondents

| Approaches following cessation of postoperative reflux (POR) to re-introduction of water and feed
The answers to this open-ended question were grouped into categories. Water re-introduction was categorised as restricted (<2 L), reduced (ie < 10 L) and free choice. Results indicated that 56%  Most respondents reported that they would re-introduce restricted water <2 L for small intestinal lesions. Re-introduction of feed would be initiated later (≥24 hours following recovery from anaesthesia), and they tended to be returned to full rations of feed later (≥4 days once re-feeding has begun) compared with many other intestinal lesions. Most respondents indicated that they would instigate re-introduction of feed with handfuls of grass or a complete, pelleted feed.

| D ISCUSS I ON
Fasting following surgery, in theory, allows healing and protection, and reduces the risks of dehiscence, peritonitis, impactions and ileus; however, there is no evidence to support starvation post-operatively, and no benefit has been demonstrated in people. [3][4][5][6][7] In the initial post-operative period, it has been anecdotally suggested in the referenced textbooks that restricting the amount of feed may minimalise potential deleterious effects on the anastomosis site. 8 In uncomplicated equine cases, trophic feeding (trickle feeding small amounts initially) is performed and advocated, whereby grass and soft feeds (eg bran mashes or soaked fibre cubes) are first introduced followed by hay, with the quantity being gradually increased, 15  to be greater 16 and good-quality forage has been considered essential in these cases. 8 There are few reports in the literature regarding the re-introduction of feed and water following resolution of caecal impactions, either with a typhlotomy or by-pass procedure. Aitken et al. (2015) demonstrated in a single-centre, retrospective case series that re-feeding did not differ between surgically or medically treated caecal impactions with the median time to first feed being 36 hours and median time to first hay being 72 hours. 17 There may be a variation of answers from respondents regarding re-introduction of feed and water for caecal impactions due to the sparse information in the reference texts. 17 Perhaps this is a less common lesion encountered by veterinary specialists. The frequency or relative frequency that the veterinary specialist encounters these surgical lesions was not ascertained in the survey.
For small colon strangulation, the starvation period was often longer compared with other lesions, and the time to reach full feeds was delayed. This delay indicated by the survey respondents maybe explained by the common perception that surgery for the correction of small colon disorders has more potential complications, such as increased risk of developing diarrhoea, when compared with surgical controls. 18 Those horses necessitating a resection and anastomosis of the small colon had a reduced long-term survival. 18 Other cases after laparotomy. 19 Those that were consuming forage within 12 hours post-operatively had a shorter recovery time. 19 Although the authors recognise the fact that horses that recover swiftly after surgery are likely to be offered EN faster than those that recover more slowly, they also suggest that EN can positively affect intestinal motility and enterocyte function to provide a beneficial effect. 19 Supplements were used infrequently for the majority of intestinal lesions in the post-operative period. However, a greater number of respondents indicated that they would use a probiotic for large colon torsions, and mineral oils were used commonly for small colon lesions.
There are minimal studies and equivocal evidence for the clinical use shedding. [25][26][27] There were limitations to the analysis of these data since not all respondents answered this question, and it was, therefore, unclear whether this item omission was because the respondents were not routinely using supplements. This was classed as missing/ unanswered data. Therefore, it is possible that the true number of 'no/ none' answers would be higher than reported here.
Intestinal dysmotility is one of the predominant concerns following equine gastrointestinal surgery, especially when small intestinal resection and anastomosis are performed. Cases of POR require intravenous fluid therapy and frequent nasogastric intubation to decompress the stomach; in such cases, parenteral nutrition may be indicated if reflux/starvation persists for >2-3 days. 13,28,29 In some circumstances, a repeat laparotomy may be necessary if POR persists. 30 The survey respondents indicated that following cessation of POR, restricted volumes of water are offered initially, followed by feeding with small quantities of predominantly grass and/or a complete, pelleted diet. A proportion of respondents indicated that they employed an ultrasound-guided approach to the re-introduction of water and feed, by assessing the stomach size, duodenal contractility and evidence of distended small intestines. In our nutrition survey, as well as a recent survey by Lefebvre et al. 10,11 regarding POI, respondents expressed the utility of ultrasound evidence of distended small intestines, small intestinal motility and duodenal contractility. There is minimal published evidence behind the ultrasound-guided approach to assessing POR 31 or the use of ultrasonography to guide re-feeding, but the use for monitoring treatment of colic has been described. 32,33 The survey had a low response rate, albeit similar to other surveys targeting equine specialists. 10,11,34 This low response rate could lead to nonresponse bias; however, the effect of this bias is difficult to ascertain since the anonymous nature of the survey precluded the analysis of the nonresponders. However, the low response rate may indicate that a portion of specialists may not be practicing veterinarians or may not be managing post-operative colic cases.
Therefore, the portion of respondents who have answered the survey may have facilitated a more accurate representation of current clinical practice. Alternatively, the low response rate may reflect a portion of clinicians who do see these cases but did not have time to respond. Individual responses were requested; however, it was possible that some practices were represented by only one specialist within the hospital. This may have also contributed to the low response rates. Results of this survey describe current clinical practice, which does not necessarily reflect the optimal approach.
There is currently no scientific evidence regarding nutritional management to increase survival and reduce complications following colic surgery. Perhaps the results from this survey will stimulate further research that could look to investigate nutritional strategies in post-operative colic cases.

| CON CLUS IONS
This study identified that there are differing approaches to refeeding post-surgical colic cases dependent on the lesion. Broadly, there were heterogeneous answers from the specialist respondents regarding the re-introduction of feed and water. However, clearer tendencies for earlier or later re-introduced feed and water for different gastrointestinal lesions can be observed when evaluating the binary logistic regression results.

E TH I C A L A N I M A L R E S E A RCH
Bell Equine Veterinary Clinic's Ethical Review Committee approved this study.

ACK N OWLED G EM ENTS
The authors thank all the Diplomates who kindly completed the equine post-operative colic nutrition survey.

CO N FLI C T O F I NTE R E S T S
No competing interests have been declared.

AUTH O R CO NTR I B UTI O N S
A. Lawson, C. Sherlock and T. Mair contributed to the study design, data analysis and interpretation, preparation of the manuscript and final approval of the manuscript. J. Ireland contributed to the data analysis and interpretation, preparation of the manuscript and final approval of the manuscript.

OWN E R I N FO R M E D CO N S E NT
Completion of the questionnaire was taken as participant consent.

DATA ACCE SS I B I LIT Y S TATE M E NT
The data that support the findings of this study are available from the corresponding author upon reasonable request.

O RCI D
April L.