EQUUS - - Eq Tack & Gear -

cen­ter­line of Cory’s ex­er­cis­ing lar­ynx. With each breath, the par­a­lyzed car­ti­lage and sag­ging vo­cal cord were dragged into his wind­pipe. His air­way was oc­cluded by 70 per­cent at work.

The dy­namic en­doscopy con­firmed what the ve­teri­nar­i­ans had sus­pected all along: Cory was a prime can­di­date for pros­thetic laryn­go­plasty, the in­stal­la­tion of per­ma­nent su­tures to hold the par­a­lyzed por­tion of the lar­ynx open. Specif­i­cally, the ary­tenoid car­ti­lage that opens and closes the lar­ynx is stitched to the cricoid car­ti­lage, cre­at­ing a fixed open­ing on the left side. The ary­tenoid car­ti­lage on the right side con­tin­ues to func­tion nor­mally, open­ing and clos­ing with each breath.

First at­tempted in 1893, pros­thetic laryn­go­plasty has un­der­gone re­fine­ments for the last 125 years. Suc­cess rates for the pro­ce­dure vary from 5 per­cent to 95 per­cent, de­pend­ing on many fac­tors: breed, use, def­i­ni­tions of suc­cess, pros­thetic ma­te­rial, vari­a­tions in tech­nique, owner com­pli­ance, re­cov­ery pro­ce­dures and re­ha­bil­i­ta­tion meth­ods. But the factor of great­est im­por­tance is sur­gi­cal ex­pe­ri­ence with pros­thetic laryn­go­plasty, and Hack­ett has that in spades. She does six of the pro­ce­dures a month.

Still, Cory’s surgery was daunt­ing to me. The worst part was see­ing him un­con­scious on a gur­ney. He was ly­ing im­mo­bile on his side, thick ropes bind­ing his feet to­gether at the pasterns, legs wrapped in heavy plas­tic, tongue dan­gling a half-foot out the side of his mouth, eyes glazed and wide open, see­ing noth­ing.

I watched as the sur­geon, res­i­dents, tech­ni­cians and up­per-level vet­eri­nary stu­dents pre­pared his body, their hands ap­proach­ing and re­treat­ing in quick move­ments like bees to a hive. A plas­tic tube the size of a drain­pipe pumped oxy­gen and anes­thetic into his air­way, and the en­do­scope was threaded up to the lar­ynx. Hack­ett could see her ma­neu­vers mag­ni­fied onto a com­puter screen as well as through the four-inch in­ci­sion she carved into Cory’s throat.

The del­i­cacy of the lar­ynx’s lo­ca­tion can­not be over­stated. Within two square inches lies the ma­chin­ery for breath­ing, eat­ing, drink­ing and cir­cu­lat­ing blood be­tween heart and brain. The ary­tenoid car­ti­lage is buried in soft tis­sue, and the cricoid car­ti­lage takes dif­fer­ent shapes among in­di­vid­ual horses, so sur­geons never know ex­actly what they will find.

The pros­the­sis must ma­nip­u­late ev­ery breath the horse takes for the rest of his life, sleep­ing or rac­ing, tran­quil or hys­ter­i­cal. That’s about 20 years, given that most lar­ynxes are cor­rected be­fore ma­tu­rity. Pros­thetic su­tures un­dergo forces of 10 pounds per swal­low---and a horse swal­lows more than 1,000 times daily. With each cough, the pros­the­sis is pres­sured even more. If it’s a lit­tle too tight or a lit­tle too loose, it will fail.

Hack­ett re­tracted tis­sue layer by layer un­til she reached the lar­ynx, then she sewed fat blue su­tures from the ary­tenoid car­ti­lage to the cricoid car­ti­lage, ty­ing the lar­ynx open. She

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