Case Fi le: Contrast-Enhanced Computed Tomography (CT)

SIGNALMENT AND HISTORY• 1-year-oldMorgancolt

• January1,2011,Trooperwasfoundwithhisleftforefoothungupinagate.

• Aboltinthegatehadcreatedapuncturewoundinthemedialheelbulb,butnootherobviousinjurieswerenoted.

• Thewoundwascleanedandthelimbwasbandaged.

• Trooper’slamenessworsenedsignificantlyJanuary18,2011.

DIFFERENTIAL DIAGNOSES• Septicjointortendonsheath

• Abscess

• Vasculardamage

• Fracture

• Tendonorligamentdamage

CONTACT INFOColoradoStateUniversity

VeterinaryTeachingHospital

300WestDrakeRoad

FortCollins,CO80523-1620

Phone:(970)297-5000

Fax:(970)297-4100

csuvth.colostate.edu

Questionsregardingthiscasefilemaybedirectedto:

KatieSeabaugh,DVM,MSClinicalInstructor

EquineSurgeryandLamenesskatie.seabaugh@colostate.edu

March2012• Volume3Appl iedResearch forToday’sEquineAthleteDiscovery

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REFERRINGVETERINARYPRACTICE

• RadiographsandVenogram(Fig.1)

Fig.1:Venogramperformedtoassessbloodflowtothefoot.Inordertoperformavenogram,atourniquetisplacedabovetheareaofinterest.Asmallbutterflycatheteristheninsertedintoaveinandcontrastmaterialisinjected.Aradiographisthentakenandthecontrastmaterialappearsthroughoutthevasculatureinthatarea.Inthisvenogram,thereferringveterinarianwasconcernedthatthevesselswerenotallvisualizedallthewaydownthefoot,suggestinglossofperfusion.

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CONCLUSIONS• Possiblemedialcollateralligamentdamageofthecoffinjoint

• Lossofvisiblevasculatureinthedistalportionofthefoot

• Prognosis–grave

JANUARY24,2011

• PresentationtoColoradoStateUniversityVeterinaryTeachingHospital

• Goal:Secondopinionandfurtherdiagnostics

PHYSICAL EXAM• Grade4/5lameontheleftfront

• Tachycardic

• Woundonthemedialheelbulbwithatriangleofthickenedskin

• Leftfronthoofwallwascooltothetouch

• Leftfrontcoronarybandwaswarmtothetouch

• Digitalpulseswerewithinnormallimitsonallfeet

• Bright,alert,responsive

• Respiratoryrateandtemperaturewerewithinnormallimits

• Smallabrasionsovertheleftfrontthirdmetacarpalbone

DIFFERENTIAL DIAGNOSES• Septicjointortendonsheath

• Abscess

• Vasculardamage

• Tendonorligamentdamage

PLAN• Contrast-enhancedcomputedtomography(CT)

Fig.2:AcontrastCTimagefromthedistalpasternregion.Thelargewhiteobjectedisthedistalportionofthesecondphalanx.Anareaofavascularitycanbeseeninthemedialheelbulbregion(redcircle).

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CONCLUSION• Probablenecrosisorabscessinthemedialheel,extendingintothesensitivelaminaofthemedialaspectofthehoof.Thisareaisrepresentedbyaregionofavascularity(lossofbloodsupply)ontheCTimages(Figs.2and3).

SURGERY• Goal:Treatthatareaasanabscessandbyopeningupthearea,pressurewouldbereleasedandtheareacouldfillinwithhealthytissue

• Debridetheareaofdevitalizedtissue

• Regionallimbperfusion–withamikacin(1g)andTimentin(ticarcillinandclavulanate,1.5g)

POST-OPERATIVE TREATMENT• Repeatregionallimbperfusions(~36hours)

• Hospitalization–4days

• Bivalved,halflimbbandagecast

• Bandagechanges

• TopicalCephapirin(Today)

PROGNOSIS• Guarded

• Highlydependentuponimprovedweightbearingontheleftfront

Fig.3:A3-dimensionalreconstructionofTrooper’sfootdemonstratinganavascularregionintheareaofthemedialheelbulb.

POTENTIAL COMPLICATIONS• Supportlimblaminitis

• Supportlimbacquiredangularlimbdeformity

• Spreadofinfectionintosynovialstructure

• Collateralbloodsupplynotsufficient

Trooperwassenthomewithinstructionstoremainonstallrestfor6weeks(Fig.4).Hewouldneedtobebandagedandinthebivalvedcastduringthistime.Anincreaseinactivitywouldbealloweddependingonhowhislamenessprogressed.

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FOLLOW UP• Stallrestwithcontrolledrehabilitation(handwalking,askinghimtopickuptherightfrontforincreasinglengthsoftime)

• Trooper’slamenesswaxedandwanedformonths.

• AttheendofApril,hebecameverylameagain.

• TrooperreturnedtoCSUforfurtherevaluation.

FOOTRADIOGRAPHS

• Distal1/3ofthedistalphalanxhadbecomeasequestrum(Fig.5).

• Thehoofhadgrownexcessivelyandwastrimmed,therebyremovingthesequestrum.

• Again,Trooper’sprognosiswasguarded.

OUTCOMETroopershowedgreatimprovementoverthenextmonth.Unfortunately,hesufferedanothersetbackinJunewhentheremainderofthecoffinbonefailedtostayattachedtothehoofwall.ThiscomplicationleftlittlehopeforanormallifeforTrooper,andwithmuchdifficulty,theCookfamilyelectedtoputTrooperdown.

CASE SUMMARYRecently,therehasbeenanincreaseinthenumberofpublicationsregardingcontrast-enhancedCTinhorses.1-6Ithasbeenusedtoassessangiogenesisofthedeepdigitalflexortendon,3toassessitsuseasanimagingmodalityinhorseswithlamenesslocalizedtothefoot,5,6andforcharacterizationofsofttissuestructureswithinthehoofcapsule.4Thereare

Fig.4:TrooperandhisfamilyalongwithDr.KatieSeabaugh(farright)asheisleavingCSUonJanuary28,2011.

veryfewreportsofcontrast-enhancedCTbeingusedtoassessbloodsupplyfollowingtraumatothelimbofahorse.InTrooper’scase,thecontrast-enhancedCTprovideduswitha3-dimensionalviewofthefootandthevesselsassociatedwithit.Wecouldeasilyvisualizeanareaofavascularity,butitwasn’tuntilmuchlaterthatwewereabletorealizetheclinical

RESOURCES• ColoradoStateUniversity

VeterinaryTeachingHospital:csuvth.colostate.edu

Fig.5:RadiographstakeninMay2011revealedseparationofthelowerpartofthecoffinbone(redcircle).Thisbonesequestrumwasbeingpushedout.Theexcessivehoofwastrimmedaway,andwithit,thesequestrumwasremoved.

AtColoradoStateUniversity,equineveterinarycareisdeliveredthroughthecollaborationofthreenationallyrecognizedequineservicecenters:

ColoradoStateUniversityVeterinaryTeachingHospitalEquineService

ColoradoStateUniversityEquineReproductionLaboratory

ColoradoStateUniversityOrthopaedicResearchCenter

EquinetreatmentcapabilitiesatCSUareattheforefrontofequineveterinarymedicinethroughthesharedexpertiseoftheseorganizations.

1. Collins,J.N.,Galuppo,L.D.,Thomas,H.L.,etal.:Useofcomputedtomographyangiographytoevaluatethevascularanatomyofthedistalportionoftheforelimbofhorses.AmericanJournalofVeterinaryResearch65:1409-1420,2004.

2. Kruger,E.F.,Puchalski,S.M.,Pollard,R.E.,etal.:Measurementofequinelaminarbloodflowandvascularpermeabilitybyuseofdynamiccontrast-enhancedcomputedtomography.AmJVetRes69:371-377,2008.

3. Puchalski,S.M.,Galuppo,L.D.,Drew,C.P.,etal.:Useofcontrast-enhancedcomputedtomographytoassessangiogenesisindeepdigitalflexortendonopathyinahorse.VetRadiolUltrasound50:292-297,2009.

4. Puchalski,S.M.,Galuppo,L.D.,Hornof,W.J.,etal.:Intra-arterialcontrast-enhancedcomputedtomographyoftheequinedistalextremity.VetRadiolUltrasound48:21-29,2007.

5. Vallance,S.A.,Bell,R.J.W.,Spriet,M.,etal.:Comparisonsofcomputedtomography,contrastenhancedcomputedtomographyandstandinglow-fieldmagneticresonanceimaginginhorseswithlamenesslocalizedtothefoot.Part1:Anatomicvisualizationscores.EquineVeterinaryJournal:no-no,2011.

6. Vallance,S.A.,Bell,R.J.W.,Spriet,M.,etal.:Comparisonsofcomputedtomography,contrast-enhancedcomputedtomographyandstandinglow-fieldmagneticresonanceimaginginhorseswithlamenesslocalizedtothefoot.Part2:Lesionidentification.EquineVeterinaryJournal:no-no,2011.

significanceofthislesion.Wenowcanappreciatethesignificanceofsuchalesionandcanusethatknowledgeforfuturecases.

Withtheadditionofanew16-slice,bigboreCTunitinradiology,weareabletoscanourequinepatientswithgreaterefficiency.Aspecializedtablewasengineeredtoaccommodatehorseheadandlegs.ThespeedatwhichtheCTunitacquirestheimagesallowsfora3-phase(arterial,venous,anddelayed)contraststudy.Thistranslatesintogreateraccuracyindiagnosingsofttissueinjuriesintheextremities.Additionally,imagingacquiredfromtheheadgreatlyincreasestheaccuracyindiagnosingandultimatelytreatingproblemsassociatedwiththeteeth,sinuses,andbonesoftheskull.Studiesarecurrentlybeingperformedwithintra-articularcontrasttofurtherevaluatethesofttissueandbonystructurestohelpinprognosisandreturntoathleticperformance.