An Update on Rodenticides
SarahJackson,RVTVTS-ECC
EasternIowaVeterinarySpecialtyCenter
Introduction
• Thegoalofthispresentationisfortechnicianstobeabletorecognizethesignsandsymptomsofdifferentkindsofrodenticidetoxicities;andtoknowthemethodandreasonfortreatment.
• Rodenticidesareavariedandeverchangingproduct.Newformulationsaredevelopedastheirtargetspeciesbecomesresistanttopreviousproducts.
Types of Rodenticides
FirstGeneration
Thesearenolongerwidelyusedduetothedevelopmentofresistanceinrodents.
• Warfarin
• Coumarin
• Indandione
SecondGeneration
Developedtohavealongerdurationofactionandtobemoretoxicthanfirstgeneration
rodenticides.
• Brodifacoum
• Bromadiolone
• Diphacinone
Thesearetypicallywhatweseeinpractice.
Anticoagulants
Types of Rodenticides
NeurotoxicDevelopedforuseagainstanticoagulantrodenticideresistantrodents.
• Bromethalin
Bromethalinwasdevelopedin1985,butonlyrecentlyhavewestartedtoseemorepatientspresentafteringestingthisproduct.
Somecompanieshavestartedtoswitchtheactiveingredientintheirrodenticidesfromananticoagulantrodenticidetobromethalin.
Types of Rodenticides
MiscellaneousLesspatientspresentwithtoxicitiesduetotheserodenticides.
• Cholecalciferol–Causesincreasedserumcalciumlevels.
• ZincPhosphide–Causesdisruptionofmitochondrialrespirationandfreeradicalproduction.
• Strychnine–Causesneurologicsymptoms.
Phone Triaging “I think my pet got into rat bait”
• Alwaysrecommendthatapetbeevaluatediftheownerthinkstheygotintorodenticide.
• Askiftheyknowwhenitcouldhavehappened;nowvs.anunknowntime.
• Havetheownerbringthepackagingtotheclinicwiththemsoyoucanverifytheactiveingredient.
• Iftheydon’thavethepackagewhentheyarrivetryandgetasmuchinformationasyoucanabouttheproductsotheactiveingredientmaybededuced.
• Apetbasedpoisoncontrolcanbecontactedwithquestions.
Patient Presentation
• InitialExam• Confirmationoftypeofrodenticide
• Contactapetpoisonhelplineifnecessary
• Decontamination• Apomorphine0.03mg/kgIV• ActivatedCharcoal1-4g/kg
Anticoagulant Rodenticides
MechanismofAction• DepletionofVitaminK
• InitiallyaffectsclottingfactorVIIresultinginaprolonged
prothrombintime(PT)48hoursafteringestion
• IfnoVitaminKisgivenclottingfactorsII,IXandXwillbeaffectedresultinginaprolongedactivatedpartialthromboplastintime(aPTT)oractivatedclottingtime(ACT)
Anticoagulant Rodenticides
• RecentIngestion• DecontaminationwithApomorphineandactivatedcharcoal.
• VitaminK(phytonadione)prescription–28days
• 2.5mg/kgPOBID• WithafattymealasVitaminKisfatsoluble
• ProthrombinTime(PT)• Either48hourspostingestionifnotVitaminKwasgivenor48hoursafterlastdoseofVitaminKifprescribed.
Anticoagulant Rodenticides
• SymptomaticPresentation• Typicallyoccursgreaterthan2dayspostingestion.
• Symptoms• Lethargy• Weakness• PaleMucousMembranes• Melena• Epistaxisis• Hematemesis
• Hematuria• Petechia• JointSwelling• Dyspnea• GingivalBleeding
Diagnostics
• Labwork• Urinalysis• CBC• PCV/TS• Chemistry• PT/aPTT
• PTwillbeelevatedafter48hours• aPTTwillbeelevatedlater
• Imaging• Radiographs• Abdominal/ThoracicUltrasound
• Checkingforeffusion
Treatment
• Frozen/FreshFrozenPlasmaorFreshWholeBloodTransfusionstorestoreclottingfactors
• PackedRedBloodCellTransfusionsforanemiaduetohemorrhage
• VitaminK• Injectable–5mg/kgSQ
• Smallgaugeneedle,multiplelocations
• Oral–2.5mg/kgPOBIDx28days
• SymptomaticTreatments• OxygenSupplementation• Thoracocentesis(aftercorrectionofcoagulopathyifpossible)
Nursing Considerations • FragilePatients
• SoftBedding• SoftFood• CautiousHandling
• Weak• Unabletomovethemselvesaroundalot
• Frequentcleaning/beddingchanges• Sanitaryclips• Offerfooddirectlywhenfeeding
• Carewhendrawingblood• Avoidjugulardrawswhenpossible• Leavepressurewrapsonabitlonger,butdon’tforgettoremovethem
Prognosis
• Thesepatients,recentexposuresandoneswithcoagulopathies,typicallyhaveagoodprognosiswhentreatmentissoughtpromptlyandaggressivemeasuresaretaken.
Molly
• 9mo,FILab• Presentedwithlaboredbreathingfollowinga3dayhistoryofprogressivecoughing
• Bloodwork• ElevatedPT/PTT• Anemia
• Radiographs/TFAST• Pleuraleffusion• Consolidatedlunglobes
Molly
• TreatmentPlan• FPTransfusion• SupplementalOxygen/SPO2Monitoring• VitaminK• MechanicalVentilation• pRBCTransfusion• RecheckRadiographs• RecheckPT/PTT
Molly
• Outcome• Dischargedafter5daysinhospital• ScheduledtorecheckwithrDVM2daysaftercompletingcourseofVitaminK
Neurotoxic Rodenticides (Bromethalin)
MechanismofAction• Bromethalinismetabolizedbytheliverintoitstoxicform,desmethyl
bromethalin• Bromethalincausestheuncouplingofoxidativephosphorylationresulting
inadecreaseinATPproduction• PumpsthatrequireATPnolongerfunctionresultinginabuildupofsodium
insidecells• Waterrushestowardthegreaterconcentrationsofsodiuminsidethecells• Manyareasofthebodycanbeaffected,butsymptomsaretypicallythe
resultofcerebraledemaandincreasedintracranialpressure
Neurotoxic Rodenticides (Bromethalin)
• ToxicDoses• Dogs–3.5mg/kg• Cats–0.54mg/kg
• AbsorptionfromtheGItractcanoccurwithin2hours• Peakplasmaconcentrationsoccurwithin4to6hours• PatientsthatingestverylargedosesofBromethalincanstarttoshowsymptomswithin2to24hours
• Patientsthatingestsmallerdosesorhavechronicexposurecanstarttoshowsymptomswithinseveraldayswithprogressionoveraperiodof1to2weeks
Neurotoxic Rodenticides (Bromethalin)
• RecentIngestion• DecontaminationwithApomorphine
• 0.03mg/kgIV
• ActivatedCharcoal• 3-5g/kgevery6-8hoursof48hours
• Toaccountforenterohepaticrecirculation
• Monitorelectrolyteswiththemultipledosesofactivatedcharcoaltomonitorforincreasedsodiumconcentrations
Neurotoxic Rodenticides (Bromethalin)
• SymptomaticPresentation• Symptoms
• MuscleWeakness• Tremors• Hyperthermia• Anorexia• Ataxia• MentationChanges• Anisocoria• Nystagmus
• RespiratoryDepression• Paresis• Coma• Seizures
Diagnostics
• Unlessingestionoftherodenticidewaswitnessednodefinitivediagnosiscanbemadepriortothedeathofthepatient.
• Postmortem,thecerebrum,cerebellum,brainstemandspinalcordmaybeexaminedhistologically.
• Diffusewhitemattervacuolation/degenerationandmicrogliosis(define)canbeseen
• Gaschromatographycanbeusedtodetectbromethalininthesesamples
Treatment • Focusontreatingsymptoms
• Seizurecontrol• Diazepam0.25-0.5mg/kgIV,toeffectPRN
• Phenobarbital3-5mg/kgIV,toeffectPRN
• Mannitol–todecreasecerebraledema
• 0.5-2g/kgQ4-6HPRN• Treattremoring
• Methocarbamol55-220mg/kgIV,toeffectPRN
• DoNotexceed330mg/kgin24hours• Monitorforexcessivesedationand
respiratorydepressionathigherdoses
Nursing Considerations • Elevateheadata15to30degreeanglewithoutcompressingthejugular
• Attempttoinclinethewholebodyofsmallerpatientsorhead/neckandshouldersoflargerpatients
• Serialbloodpressures• Increasedcerebralpressurecausesdecreasedcerebralbloodflow
• Monitorhydrationandurineoutput• RecumbentPatientCare
• RotatepatientsQ4Htohelppreventbedsoresandatelectasis• Thick,softbedding• Frequentcleanings/beddingchanges• Supportwhenwalking(ifable)• Offerfood/waterdirectlyifLOCisappropriate• Lubricateeyes
Prognosis
• Withrecentingestionandpropertreatmentmanyofthesepatientshaveagoodoutcome,butifthepatientpresentsalreadysymptomatictheprognosisisverypoor.
Hank
• 7yoMNLaborador• PresentedforBromethaliningestion–2blocks,40minutespriortopresentation
• Apomorphine0.03mg/kg• Toxibanw/sorbitoladministered• Electrolytepanel6hourslater
• Na–150mmol/L(144-160)• K–4.0mmol/L(3.5-5.8)• Cl–113mmol/L(109-122)
• Toxibanw/osorbitoladministered
Miscellaneous Rodenticides
• Cholecalciferol• Resultsinhypercalcemiaduetoincreasedabsorptionofcalciumanddecreasedrenalexcretionofcalcium
• Symptoms• PU/PD• Lethargy• Anorexia• Vomiting
• Acutekidneyinjuryandcardiacarrhythmiascandevelop• DecontaminationwithApomorphineandActivatedCharcoal• Treatmentincludesreducingbloodcalciumlevelsandpreventingkidneyinjury• PrognosisisfairtogoodwithtreatmentpriortohypercalcemiaandAKIoccurringinwhichcasesprognosisbecomespoor
Bonnie
• 4yo,FIAustralianCattleDog• Presentedforvomitingandpotentialtoxiningestion• Contactedpoisoncontrol• Urinalysis
• Crystalfragments
• EthyleneGlycoltesting• Bloodwork
• Hypercalcemia• Azotemia• Hyperphosphatemia
Bonnie
• TreatmentPlan• FluidDiuresis
• NaCl• UrineProductionMonitoring• Pamidronate• RecheckBloodwork• ECGMonitoring
Bonnie
• Outcome• Dischargedinitiallyafter4daysinhospital
• Presentedforrecheckonedaylater• SQfluidsandmirtazapineadded
• Presentedforadditionalrecheckafterafurther4daysandhospitalizedforanadditional2days
• Prednisoneadded• Furtherrecheckinoneweekrecommended
Resources
• ASPCAAnimalPoisonControlCenter
• 888-426-4435• $65
• PetPoisonHelpline• 855-764-7661• $59