ScotiaDuckTollingRetriever.Thatbreedwasfoundedwith
only11dogs.ShesaidthatTollersaremorerelatedtoeach
otherthanarefullsiblings.Sheanalyzedtherelatedness
ofseveralotherbreedsandfoundthatTollersarenotan
extreme;infact,therearemanybreedsthataremorerelated
thanTollers.

Dr.Bannaschnextturnedtowhatweknowaboutthe

newlyidentifiedPOAGgenemutationinPBGVs.Hereare
somePOAGfacts:

I

Ithasarecessivemodeofinheritance.Thus,adog

musthavetwocopiesofthemutationtodevelopPOAG.
Whenevertwocarriersarebred,everypuppyhasa25
percentchanceofhavingthedisease.

I

Itsleadtodiseaseiscompletelypenetrant.Thatmeans

thateverydogwithtwocopiesofthegenemutationwill
developPOAG.

I

Itappearstobetheonlygenemutationthatleads

toPOAGinourbreed.DogsthatareclearofthePOAG
mutationcanstilldevelopothertypesofglaucoma,but
theywon’tdevelopthispredominantformofglaucoma.

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Thegenemutationleadstoseverepainandblindness

withfewtreatmentoptions.NowthataDNAtestisavailable
forPOAG,affectedpuppiesshouldnotbeproduced.All
breedingstockshouldbetestedbeforebeingbred.

Dr.BannaschsaidthatthePBGVcommunityhasawon-

derfulfutureofmakinghealthierdogsusingthePOAGtest.
Shegaveheradvicetotheclubasageneticist:“Youcan’t
helpthefactthatafewanimalsfoundedthebreed...but
therearesomethingsthatbreedersdothatcanreallymess

updiversityinabreed.Thatis,thepopular-sireeffect,
breedingtothetop-winningdogbecauseitisthe
top-winningdog.AndwhatIchallengeyouwith,
asbreeders,istothinkaboutlimitingtheuseof
popularsiresto10litters.Idon’tseeanyreasonwhy
astuddogshouldhavemorethan10litters.Itis
excessiveand,inasmallbreedlikethis,10might
betoomuch.“

Shereiteratedthatuseofapopularsireleadsto

inappropriatedistributionofthatdog’sgenes
throughoutabreed.Ifapopularsirehappenstocarry
amutation,thenthatmutationwillbespreadacross
thebreed.Thedogmaylookgoodandwininthe
showring,butitmaybecarryingatraitthatleadsto
aninheritablehealthissue.

POAGisoneofmorethan300disease-causing

mutationsthathavebeenidentifiedindogsand,at
thispointintime,onlytheAHToffersthetest.
Withtime,however,othercompanieswillofferthe
POAGtestandotherPBGV-specifictestswillbecome
available.Dr.Bannaschcautionedustoonlyuse
reputabletestingcompanies.Qualitycontrolvaries
fromcompanytocompany,andDNAtestingfor
animalsisnotregulated.Shesaidthatsome
companiesarehappytotakeyourmoneyandtest

fordisease-causingmutationsthatarenotrelevantto
PBGVs.Fortunately,theAHTisasreputableasitgets.Her
adviceistoonlyusegenetic-testinglabsthatareassociated
withuniversitiesornon-profitorganizations.

HowcommonisthePOAGmutationinPBGVs?TheAHT

informedDr.Bannaschthat,intheUK,10percentofthe
testedPBGVshavebeenidentifiedasaffected,40percentare
carriers.Thisinformationelicitedagaspfromtheaudience.
IntheUK,POAGisacommondiseaseinPBGVs,notarare

one.Whenadiseaseiscommon,itcan’tbeeliminatedquickly.
Dogsthatdon’tcarrythePOAGmutationarenotgenetically
perfect.Itwillbedifficulttoidentifydogsthatarenotcarriers
ofonethingoranother.Aswiftchangeinthepopulation
mightuncoverotherdiseases.Dr.Bannaschstated,“Not
everydogmustbebred.Nodogshouldbebredexcessively!”

HowshouldthePBGVcommunityhandlePOAG?She

said,ifyourdogisclear,itisnotbecauseyouareabetter
breeder.Ifyourdogisaffected,itisnotbecauseyouare
aworsebreeder.Dr.BannaschadvisedthatthePBGV
communitymustsupportoneanotherthroughthis.Ifthe
diseasefrequencyintheUnitedStatesisashighinasinthe
UK,wemustbecompletelyopenaboutourtestresults.She
suggestedreleasingalltestresultsthroughtheonlineOFA
database.Itispossibletoclearadogbyparentage(ifboth
parentsareclear,allpuppiesinthelitterwillbeclear).
Nevertheless,shecautionedbreederstotestapopular
sireevenifthedoghasbeenclearedbyparentage.

Canyoubreedanaffecteddog?Dr.Bannaschsaid,yes.

Ifabitchturnsouttobeaffected,thenbreedhertoclear;
youwillgetallcarriers.Next,breedthosecarrierstoclear.In
twogenerationsyouwillhavenormaldogs.Thisiscalleda
breed-and-replacestrategy.Ifyoudon’tbreedanyaffected
dogs,youareeliminating10percentofthepopulation.Can
youbreedtwocarriers?Dr.Bannaschsaid,no.Thatbreeding
willcertainlyproducesomeaffecteddogs.“Asaveterinarian,
Icannotrecommendproducingaffecteddogs.”

ThePBGVCAHealthCommitteeasksyoutopleasetest

yourdogs.Itismostimportanttostartwithyourbreeding
stock;however,evenspayedandneuteredPBGVsshouldbe
testedtoidentifywhichmightdevelopthispainfuldisease.
ThePBGVHealth&RescueFoundationwillreimburse$40
perdogtoPBGVCAClubmemberswhotesttheirdogsand
submittheresultstotheOFAdatabase.Inaddition,PBGV
ownerswhoresideinNorthAmerica,butwhoarenotclub
members,arealsoeligibleforthereimbursement.Inorderto
receivethereimbursement,theownermustcompletethe
ApplicationforDNABasedGeneticDatabasefoundat
www.offa.org/pdf/dnaapp_bw.pdfandsubmittheformto
OFAalongwithacopyoftheAHTPOAGresults.Senda
copyoftheOFAconfirmationbymailoremailtoFoundation
TreasurerJoAnneHacker,10832N.E.CountryClubRoad,
BainbridgeIsland,WA98110-2337(jah@arcanumltd.com).

Thankyoutoallwhohavetestedalready.Please

encourageotherstodothesame.

I

SaberTails

ISummer2015

www.pbgv.org

65

UpdateonthediseasefrequencyintheUnitedStates:AsofJune1,POAGtestresultswereinfor

138PBGVs.Sixwereaffected,63arecarriersand69testednormal.Thesepreliminaryresults

indicatethatthediseasefrequencyintheUnitedStateswilllikelybesimilartothatintheUK.