mutationmeansthat
heartmusclesdon’thaveenoughenergytoworkproperly.
Unfortunately,thisfindingwillnothelptheDobermansin
Europe,sinceitisthoughtthattheUnitedStatesand
EuropeanDobermanshavedifferentgenedefects.
Incontrast,DCMinGreatDanesisanX-linkedrecessive
trait.Withthismodeofinheritance,femalesthatinherit
onediseasegenearesilentcarriersofthedisease.Whena
femalecarrierhaspuppies,hermaleoffspringhavea50
percentchanceofbeingaffected!Affectedfemalesonlyarise
whenanaffectedmaleisbredtoacarrierfemale.
Whenadoghasadisease-causingmutation,thatdoesn’t
alwaysmeanthatthedogwilldevelopsymptomsofthe
disease.Thisfeatureofageneticdiseaseiscalledpenetrance.
Forexample,arrhythmogenicrightventricularcardiomy-
opathyisanautosomaldominantheartdiseasethatprimarily
affectsBoxers.Thegenedefecthasbeenidentifiedanda
genetictestisavailable.However,30percentofBoxerswith
thegenedefectneverdevelopdisease.Perhapstheyare
protectedbyothergeneticfactors,theenvironment,diet
oractivities.Ifthegenetictestindicatesthatadoghas
onecopyofthegenemutation,thatdogwillbeclinically
normalbutcanstillpassonthegenedefect.Therefore,the
dogshouldbebredonlytodogsthathavenomutation.If
thegenetictestindicatesthatadoghastwocopiesofthe
genemutation,thatdogshouldbeclinicallyevaluatedevery
yearandonlybredifitisanexceptionaldog.Theseexamples
remindusthathavingagenetictestforacaninedisease
doesnotalwaysleadtoastraightforwardpathforeliminating
thediseasefromthebreed.
Cataracttherapeutics.Cataractsarethemostcommon
causeofblindnessinhumansanddogs.Theycanbecaused
bytheagingprocess,exposuretoultravioletrays,oxidative
stress,metabolicdisordersorgeneticfactors.Indogs,there
isnobreedpredilectionforcataractformation.Theonly
treatmentoptionissurgerytoremovethecataractouslens
andimplantanewintraocularlens.
HeatherChandler,PhD,isanAssistantProfessorinthe
OhioStateUniversityCollegeofOptometry.Sheisstudying
acommoncomplicationofcataractsurgerycalledposterior
capsuleopacification(PCO).Thisoccurswhensomeofthe
cataractmaterialisleftbehindaftersurgery.Thesecellsgrow
andobscurevisionthroughthenewlens.Thishappensin
30to50percentofadulthumanswhohaveanintraocular
lensandin80-100percentofdogs.HumanswithPCOare
treatedwithalaserbeamtodestroythegrowingcells.This
treatmentisveryexpensiveandnotverysuccessfulindogs.
ThePBGVHealth&RescueFoundationfundedDr.
Chandler’sAKCCanineHealthFoundationgranttotesta
newtherapeuticstrategy.Shehasfoundapharmacological
agent,calledcyclosporine,thatkillsthecataractcellsthat
aregrowingback.Fortunately,thecyclosporinedoesnot
harmtherestoftheeye.Thesetestsareperformedincanine
eyesthathavebeenremovedforotherreasons.Dr.Chandler
isnowinvestigatinghowtodeliverycyclosporinetocanine
patientsandwhetherlong-termadministrationofthedrug
hasanyharmfuleffects.
Bloatandmultipleorganfailure.Bloat,alsoknown
asgastricdilatationvolvulus,referstodistensionofthe
stomachbygasandfluidfollowedbyrotationofthe
distendedstomachonitslongaxis.Therotationpinchesoff
thestomachandpreventsthegasandfluidfromescaping.
Stomachtissuecandieduetothelossofbloodcirculation.
Furthermore,thetwistingcancausehemorrhaging.Large
breeddogswithdeepchestsaremoresusceptibletobloat,
butthislife-threateningemergencycanoccurinanydog.
ElizabethRozanski,DVM,AssociateProfessorofClinical
SciencesatTuftsCummingsSchoolofVeterinaryMedicine,
describedhowbloattreatmenthasevolved.Fiftyyearsago,
mostdogsdidn’tsurvivebloat.Thischangedwhenitwas
realizedthatimmediatesurgeryisnecessarytocorrectthe
twistedstomachandremovedeadtissue.Today,bloatisa
survivabledisease.Aretrospectivestudyof498dogspresent-
ingatTuftsforsuspectedbloatrevealedthat24percentof
dogswereeuthanizedattimeofdiagnosis.Oftreateddogs,
84percentsurvived.Giventhehighrateofsuccess,whyare
somanyaffecteddogseuthanized?Amajorfactoriscostof
treatment,whichcanrangefrom$2,000to$8,000.
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