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of 90 months (Bauck et al. 2017a) surpass responses to lidocaine (Malone et al. 2006) or any drug in colic-related studies. By comparison, the slower resolution of POR with lidocaine (Malone et al. 2006), needs to be regarded with caution in a disease that can resolve spontaneously (Nolen- Walston et al. 2007). I disagree with Dr Blikslager’s hypothesis that
“pharmacological management of POR is effective in the absence of technical surgical errors”, largely because it is impossible to rule out a technical error or a physical obstruction in any horse, simply because it is discharged after one surgery. Presumably technical errors or surgically related complications can produce a broad continuum of physical changes that cause different degrees of intestinal obstruction. Any form of physical obstruction (e.g. anastomotic stenosis) that causes POR could have a transient effect, possibly because it is sufficiently mild to allow recovery of intestinal function shortly after surgery, either through resolution of the obstruction or adaptation to it. Such “recoveries” could explain the increased risk for death after hospital discharge in horses that developed POR/POI (Fogle et al. 2008) but “responded tomedical treatment.” Dr Blikslager’s comment about the rarity of technical
errors raises the concern that he dismisses the importance of such errors in outcome. I imagine that we all commit more errors than we think, especially in as complicated a surgery as resection and anastomosis, and denial is not the pathway to prevent them. Some technical errors are unexpected (Freeman and Schaeffer 2010) and some forms of physical obstruction are difficult to prevent or recognise (Bauck et al. 2017a). However, most of them are poorly tolerated and so we should all be circumspect about our potential role in their development. I cannot agree with the comment that “we also know that
intestinal inflammation is exacerbated by the administration of flunixin meglumine”. The paper cited to support this statement
examined mucosa only (Cook et al. 2009) and not the muscle layers that are relevant to POI. More importantly, flunixin meglumine did not increase inflammation in the muscle layers and serosa after ischaemic injury in another study that Dr Blikslager coauthored (Little et al. 2005). The claim that I overlooked evidence in favour of pharmacological treatment is true, largely because such evidence is weak or lacking (Freeman 2018a,b). The statement that the exacerbation of inflammation was “ameliorated by administration of lidocaine” also relates to the study on the mucosal layer only (Cook et al. 2009), whereas a more recent study could not consistently demonstrate an antiinflammatory effect of lidocaine across all layers in different models of jejunal inflammation (Bauck et al. 2017b). I fully agree and have stated that lidocaine does
provide visceral analgesia (Freeman 2018b), especially with flunixin meglumine (Cook et al. 2008). The study supporting Dr Blikslager’s statement, “inflammation
that occurs following small intestinal manipulation, which is clearly increased within the muscle layers during the recovery period” (Little et al. 2005) actually did not examine response to manipulation in equine small intestine, in any layer. Undoubtedly surgically relevant manipulation does induce inflammation in intestinal muscle layers in horses (Bauck et al. 2017b), but transferring this information from laboratory animals to POR in horses lacks support (Freeman 2018a). For example, the inflammation theory for POR embraced by Dr Blikslager would seem to predict that a repeat celiotomy, with as much manipulation and inflammation as induced at the first surgery,
would exacerbate POR; the opposite seems to be true (Bauck et al. 2017a). Dr Blikslager should recognise that horses with strangulated
small intestine deemed viable and not resected do not seem particularly prone to POR/POI or post-operative endotoxaemia (Freeman et al. 2014). This is critical because these horses are the clinical correlates of the ischaemia and reperfusion models that Dr Blikslager uses to advance his inflammation hypothesis (Little et al. 2005; Cook et al. 2009). These clinical cases, with favourable survival rates, but without lidocaine and with full- dose flunixin meglumine (Freeman et al. 2014) do not support his views about pharmacological management of post- operative complications. The last statement in Dr Blikslager’s letter causes the most
concern. It reads as if we should dismiss studies with “differing objectives and outcomes,” whatever that means, and focus only on randomised controlled trials (RCTs). This would seem to relegate other studies, including mine, to outlier status and promote the types of studies he favours asmore reflective of the direction to follow. Surely, the objectives and outcomes of all studies are the same for the “colic population at large” and that is to improve survival rates and reduce complications, suffering and cost. He faults my studies as having “relatively smaller numbers of horses,” which is interesting considering that they have larger numbers, alone or in combination, than the RCTs he cites, twice as many for some of the objectives examined (Malone et al. 2006; Ziegler et al. 2019). I agree that RCTs play an important role in studying these issues, but biases in design and data presentation (Blikslager 2018; Ziegler et al. 2019) need to be resolved before they can allow “informed choices.” In the meantime, if Dr Blikslager embraced the message in papers he dismisses, he might find that positive outcomes can be achieved with “differing objectives,” an appropriate degree of optimism, and without expensive pharmacological management.
D. E. FREEMAN Department of Large Animal Clinical Sciences,
College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA
References
Bauck, A.J., Easley, J.T., Cleary, O.B., Graham, A.S., Morton, A.J., R€
otting, A.K., Schaeffer, D.J., Smith, A.D. and Freeman, D.E. (2017a) Response to early repeat celiotomy in horses after a first surgery for jejunal strangulation. Vet. Surg. 46, 843-850.
Bauck, A.G., Grosche, A., Morton, A.J., Graham, A.S., Vickroy, T.W. and Freeman, D.E. (2017b) Effect of lidocaine on inflammation in equine jejunum subjected to manipulation only and remote to intestinal segments subjected to ischemia. Am. J. Vet. Res. 78, 977-989.
Blikslager, A. (2009) Advances in management of small intestinal diseases causing colic. Proc. Am. Assoc. Equine Pract. 55, 207-211.
Blikslager, A. (2018) Two-year study shows improved survival rates in horses treated with firocoxib. BloodHorse 144,48.
Blikslager, A.T. (2020) Letter to the Editor: Post-operative reflux – a surgeon’s perspective. Equine Vet. Educ. 32, 52-53.
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, M.R., 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.
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