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