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EQUINE VETERINARY EDUCATION
Equine vet. Educ. (2020) 32 (1) 52-53 doi: 10.1111/eve.13116
Correspondence Letter to the Editor: Post-operative reflux – a surgeon’s perspective
Post-operative reflux - an alternate perspective There have been two recent articles written by D.E. Freeman, including an editorial in the Equine Veterinary Journal (‘50 years of colic surgery’) (Freeman 2018a) and the present article (‘Post-operative reflux – a surgeon’s perspective’ [Freeman 2018b]) which propose that there is an escalating level of post-operative reflux noted in horses following small intestinal surgery at veterinary hospitals except those associated with the aforementioned author. Coupled with this assertion is the impression that surgeons are overly pessimistic about prognosis and are far more reliant on pharmacological treatment of post-operative reflux (POR) or the associated syndrome of functional post-operative ileus (POI). In terms of pessimism, it is noteworthy that Freeman et al. euthanised 22% of horses with small intestinal surgery in a 2000 article under anaesthesia (Freeman et al. 2000) which perhaps stimulated a change in opinion, although this is not explained in the present Equine Veterinary Education article. I propose that the most ethical practice with colic surgery is to present a realistic prognosis to the owner prior to surgery, and to refine the prognosis at the time of surgery, considering additional expenses and the emotional impact of post- operative outcome. The key in my view is realism in view of all the literature that has been published vs. pessimism. The surgeon’s perspective proposed by Freeman has a
number of numerical errors, although I have not been through all of the values within particularly figure 2 of the present article. The prevalence in the Blikslager 92–94 study was not 47%, but 21%, as stated in the original manuscript (Blikslager et al. 1994). This incorrect number was also reported by Freeman in the Equine Veterinary Journal editorial (Freeman 2018a,b). In another study by Fogle et al., Freeman has picked apart the data to make a point that the prevalence of POI was 70%, but this only included 33 horses receiving carboxymethylcellulose for the first time in a clinical study, whereas the prevalence in the remaining 170 horses was 44% (Fogle et al. 2008). I agree that these numbers are concerning and that we should seek better methods to reduce POR. However, a similar splitting of percentages could be applied to a study by Freeman et al., in which 18% of horses with a handsewn side-to-side jejunocaecal anastomosis developed colic and POR, but 70% of horses with a stapled side-to-side jejunocaecal anastomosis developed colic and POR (Freeman and Schaeffer 2010). These numbers are merged with numbers from two other studies to give a far lower rate of approximately 10% in the present Equine Veterinary Education article (Freeman 2018b [see figure 2, legend]). Overall, the hypothesis appears to be that repeat
celiotomy is the key approach to POR to address technical errors, particularly shortened mesentery and anastomotic stenosis. This brings up a couple of points. Firstly, these complications are unusual in my view, especially mesenteric shortening, which can be obviated by leaving the mesentery as long as possible in resection cases (ligating within approximately 6–8 cm of the margin of the bowel), and avoiding ‘gathering’ of the cut mesentery, as has been
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indicated by Freeman (Freeman 1997). The second point is that repeat laparotomy adds greatly to the expense in many hospitals and is a particularly rigorous approach to POR given that most horses will stop refluxing within 48-h of medical management, particularly those on lidocaine (Malone et al. 2006). Overall, I would suggest a different overall hypothesis: pharmacological management of POR is effective in the absence of technical surgical errors. There is evidence to support why this might be the case that the author has overlooked. Dr Freeman mentions equine studies assessing the inflammation that occurs following small intestinal manipulation, which is clearly increased within the muscle layers during the recovery period (Little et al. 2005). We also know that intestinal inflammation is exacerbated by the administration of flunixin meglumine and ameliorated by administration of lidocaine (Cook et al. 2009). There is also the analgesic effect of lidocaine, particularly when given in combination with flunixin meglumine, that should not be over-looked (Cook et al. 2008). I am in favour of reducing unnecessary usage of medications in post-operative colic patients but I think this has to be done carefully based on evidence which is still forthcoming in the form of multi- institutional randomised controlled trials (Ziegler et al. 2019). I would strongly encourage broad involvement in randomised controlled trials to gather the evidence we need to make informed choices on management of equine syndromes such as POR/POI. Ultimately, it is the entire population of post-operative colic patients that we are trying to address, rather than the relatively smaller numbers of horses that have been published in studies with differing objectives and outcomes.
A. T. BLIKSLAGER
Department of Clinical Sciences, North Carolina State University, Raleigh, North Carolina, USA
References
Blikslager, A.T., Bowman, K.F., Levine, J.F., Bristol, D.G. and Roberts, M.C. (1994) Evaluation of factors associated with postoperative ileus in horses: 31 cases (1990-1992). J. Am. Vet. Med. Assoc. 205, 1748-1752.
Cook, V.L., Jones Shults, J., McDowell, J.M., Campbell, N.B., Davis, J.L. and Blikslager, A.T. (2008) Attenuation of ischaemic injury in the equine jejunum by administration of systemic lidocaine. Equine Vet. J. 40, 353-357.
Cook, V.L., Jones Shults, J., McDowell, M.R., Campbell, N.B., Davis, J.L., Marshall, J.F. and Blikslager, A.T. (2009) Anti-inflammatory effects of intravenously administered lidocaine hydrochloride on ischemia- injured jejunum in horses. Am. J. Vet. Res. 70, 1259-1268.
Fogle, C.A., Gerard, M.P., Elce, Y.A., Little, D., Morton, A.J., Correa, M.T. and Blikslager, A.T. (2008) Analysis of sodium carboxymethylcellulose administration and related factors associated with postoperative colic and survival in horses with small intestinal disease. Vet. Surg. 37, 558-563.
Freeman, D.E. (1997) Surgery of the small intestine. Vet. Clin. North Am. Equine Pract. 13, 261-301.
Freeman, D.E. (2018a) Fifty years of colic surgery. Equine Vet. J. 50, 423-435.
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