PAINKILLERS MAY AF­FECT COLIC COM­PLI­CA­TIONS

EQUUS - - Medicalfront -

com­pro­mise of ad­ja­cent syn­ovial struc­tures. In ad­di­tion to cy­tol­ogy, each horse’s records also con­tained re­sults of di­ag­nos­tic imag­ing tech­nique called pos­i­tive­con­trast ra­di­og­ra­phy.

“The tech­nique in­volves in­ject­ing ra­dio­graphic con­trast ma­te­rial into a joint, ten­don sheath or bursa in prox­im­ity of a wound from a re­mote lo­ca­tion [mean­ing not through the wound it­self] to dis­tend the syn­ovial cav­ity,” ex­plains David M. Bolt, MRCVS, spe­cial­ist in equine surgery at RVC Equine. “If the [struc­ture] has been pen­e­trated by the in­jury, the leak­ing of fluid can be vi­su­al­ized with a ra­dio­graph.”

Based on the cy­tol­ogy re­sults, re­searchers di­vided the study horses into two groups: those with in­fec­tions of the syn­ovial struc­tures and those with­out. They then com­pared that data with the re­sults of the pos­i­tive-con­trast ra­di­og­ra­phy. They found that pos­i­tive-con­trast ra­di­og­ra­phy had a low pos­i­tive pre­dic­tive value and a high neg­a­tive pre­dic­tive value, mean­ing the test would not by it­self re­li­ably enough con­firm syn­ovial in­volve­ment in all cases, but that it could be use­ful to rule out a syn­ovial breach with rea­son­ably ac­cu­racy.

“This tech­nique is not meant to re­place the gold stan­dard of cy­to­log­i­cal anal­y­sis of a syn­ovial fluid sam­ple,” says Bolt. “It is a com­ple­men­tary modal­ity that can con­firm con­tam­i­na­tion in cases where no fluid sam­ple can be ob­tained.”

Chronic in­fec­tion af­ter com­pro­mise of a syn­ovial struc­ture can be dif­fi­cult to treat, mak­ing an early di­ag­no­sis crit­i­cal, says Bolt. “The gold stan­dard treat­ment for syn­ovial in­fec­tion is lavage with the arthro­scope whilst de­brid­ing and clos­ing the wound at the same time. This pro­ce­dure is as­so­ci­ated with cost and anes­thetic risk, so it is im­por­tant to es­tab­lish, if the pro­ce­dure is ac­tu­ally nec­es­sary. If the syn­ovial struc­ture is not con­tam­i­nated, sim­ply su­tur­ing the wound in the stand­ing horse and treat­ment with an­ti­in­flam­ma­to­ries and an­tibi­otics is ef­fec­tive.”

Ref­er­ence: “Use of pos­i­tive con­trast ra­di­og­ra­phy to iden­tify syn­ovial in­volve­ment in horses with trau­matic limb wounds,” Equine Vet­eri­nary Jour­nal, June 2018

Re­duc­ing the risk of a lifethreat­en­ing com­pli­ca­tion of small in­tes­tine stran­gu­la­tion colic can be as sim­ple as se­lect­ing the right type of painkiller, ac­cord­ing to new re­search from the Univer­sity of North Carolina.

The study fo­cused on the role of post-sur­gi­cal med­i­ca­tions on the de­vel­op­ment of en­do­tox­emia.

“En­do­tox­emia oc­curs when the bac­te­rial toxin, called en­do­toxin, gets across the lin­ing of the gut and ac­ti­vates a mas­sive im­mune re­sponse, caus­ing shock (poor or­gan blood flow),” ex­plains

Chronic in­fec­tion af­ter com­pro­mise of a syn­ovial struc­ture can be dif­fi­cult to treat, mak­ing an early di­ag­no­sis crit­i­cal.

it is more likely to oc­cur in small in­testi­nal stran­gu­lat­ing ob­struc­tion (SISO) of the gut is that the lin­ing of the gut breaks down rapidly in those cases, al­low­ing en­do­toxin to get across and into cir­cu­la­tion. In sim­ple ob­struc­tions, like im­pactions, this takes much longer. “

In­flam­ma­tory en­zymes, such as COX-2, con­trib­ute to pain and in­flam­ma­tion as­so­ci­ated with ill­ness, in­jury and surgery. Non­s­teroidal anti-in­flam­ma­tory drugs (NSAIDs), block this en­zyme and are com­monly ad­min­is­tered af­ter colic surgery. How­ever, COX-1, which is closely re­lated to COX-2, pro­duces prostaglandins that pro­tect the stom­ach lin­ing. This means that block­ing both COX-1 and COX-2 has many ben­e­fits, but can also lead to neg­a­tive gas­troin­testi­nal side ef­fects be­cause of the im­por­tance of COX-1. Some NSAIDs, such as flu­nixin meg­lu­mine, in­hibit both COX-1 and COX-2, while se­lec­tive in­hibitors, such as firo­coxib, tar­get only COX-2 in­hibitors and pro­duce fewer side ef­fects.

“In this study, the ul­ti­mate ques­tion was, ‘Does a non­s­e­lec­tive NSAID (flu­nixin---which blocks COX-1 and COX-2) stop the gut from re­pair­ing rapidly as com­pared to a se­lec­tive NSAID (firo­coxib---which blocks COX-2)?’” says Blik­slager.

The re­search was based on 56 horses who un­der­went surgery to re­pair SISO at three univer­sity clin­ics over a two-year pe­riod. Af­ter surgery, the horses were given ei­ther firo­coxib or flu­nixin while re­searchers mon­i­tored their pain lev­els and blood­work for pro­duc­tion of a mol­e­cule called sol­u­ble CD14 (sCD14), one of the ear­li­est signs of en­do­tox­emia that is re­leased by im­mune cells when they de­tect en­do­toxin.

The data showed that while there was no dif­fer­ence in pain lev­els among the groups, horses given flu­nixin had more than three times the risk of hav­ing el­e­vated sCD14 in their blood. “The re­sults sug­gest flu­nixin does slow down gut re­pair, al­low­ing more en­do­toxin to get across,” says Blik­slager. “This makes it less de­sir­able, de­spite its abil­ity to con­trol signs of pain.”

Based on the find­ings of this study, Blik­slager says he’d rec­om­mend giv­ing horses a se­lec­tive COX-2 in­hibitor fol­low­ing SISO surgery, “be­cause it treats pain well, but re­duces the risk of slow gut re­pair and en­do­tox­emia. In fact, for any horse in the field sus­pected of the be­gin­ning stages of SISO, I would use a se­lec­tive COX2 in­hibitor. The next phase of this study is to take it to the field, be­cause once flu­nixin is used, it takes up to 24 hours for COX-1 ac­tiv­ity to come back.”

Ref­er­ence: “Mul­ti­cen­tre, blinded, ran­domised clin­i­cal trial com­par­ing the use of flu­nixin meg­lu­mine with firo­coxib in horses with small in­testi­nal stran­gu­lat­ing ob­struc­tion,” Equine Vet­eri­nary Jour­nal, Au­gust 2018

The study asked the ques­tion, “Does a non­s­e­lec­tive non­s­teroidal anti-in­flam­ma­tory drug [NSAID], which blocks COX-1 and COX-2, stop the gut from re­pair­ing rapidly as com­pared to a se­lec­tive NSAID that blocks COX-2?”

SMALL COLONSMALL IN­TES­TINECECUM STOM­ACH EQUINE DI­GES­TIVE SYS­TEM

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