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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
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.