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POS 2 > Toxicology > Flashcards

Toxicology Flashcards

1
Q

What info should be ascertained from the hx?

A
  • what toxin?
  • how much
  • species/breed/BW (signalment stuff)
  • when (can you decontaminate? when should they show clinical sings?)
  • clinical sings
  • V+
  • other eg. medications, chronic illness
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2
Q

What presenting problems may be linked to toxin ingestion?

A
  • neuro (seizure, tremor)
  • renal azotaemia
  • haemotologic (anaemia, coagulopathy)
  • CV (tachycardia, arrhythmia)
  • hepatic/GIT
  • metabolic (hypoglycaemia, acidaemia)
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3
Q

Give an acronym for DDx

A

VITAMIN D

  • vascular
  • inflame/infection/immune mediated
  • toxin/trauma
  • anomalies
  • metabolic
  • idiopathic/iatrogenic
  • neoplasia/nutritional
  • degenerative
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4
Q

What categoried of toxin are possible and what must be remembered about these?

A
  • plants
  • animals
  • fungi
  • inorganic material
  • drugs/medicines (human/vet)
  • pesticides (domestic/agricultural)
  • household chemicals/industrial chemicals
    > classifcations are artificial (drugs are chemmicals, food can be plants etc.)
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5
Q

Egs of low toxicity? (assuming acute exposure, and will still be risk of mechanical damage etc. so not harmless)

A
  • baby wipes/nappies
  • nappy rash cream
  • folic acid
  • HRT tablets
  • oral contraceptives
  • zinc oxide cream
  • coal
  • cut flower food
  • expanded polystyrene
  • icepacks
  • lipstick
  • matches
  • silica gel
  • emulsion paint
  • rubbers
  • PVA or super glue
  • blue tack
  • chalk
  • crayons/pencils/paper
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6
Q

What is involved in toxicoKINETICS and toxicoDYNAMICs?

A 
> kinetics (getting to site of action) 
- uptake
- transport
- metabolism and transformation 
- sequestration 
- excretion
> dynamics (once at site of action, protein binding/cellular changes/cytoprotection)
- binding
- interaction 
- induction of toxic effects
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7
Q

How may normal drugs kinetics be altered?

A
  • if overdosed, kinetics are different to at therapeutic doses
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8
Q

What should tx of a patient with potential toxin ingestion be based on?

A

Tx the patient not the toxin eg.

  • Arrythmia - ECG, antiarrythmics
  • shock - IVF bolus
  • Resp problems - O2
  • neuro seizures - Diazepam, propofol, phenobarbital
  • neuro tremors - methocarbamol, diazepam
  • hyperthermic - cool to 39.3
  • check blood (glucose, PCV/TP and smear, coagulation PT and APTT, biochem and haem)
  • urinalysis
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9
Q

What are PT and APTT?

A

coagulation parameters

  • prothrombin time
  • activated partial thromboplastin time
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10
Q

What should be considered before treating a toxin patient?

A
  • what is it (caustic? acid alkali bleach)
  • when?
  • how much? (toxic dose LD50)
  • recumbent/seizuring/gag reflex?
  • pharmacokinetics (enterohepatic metabolism/renal excretiong/charcoal binding/antidote?)
  • risks of Tx
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11
Q

Potential tx for toxin ingestion

A
  • emesis
  • milk
  • gastric lavage
  • enema
  • activate charcoal
  • sorbitol (cathartic)
  • IVF
  • fermal decontamination
  • antidotes
  • lipids (intralipid)
  • dialysis
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12
Q

Indications for emesis?

A
  • ingestion RECENT
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13
Q

potential complications of emesis

A

aspiration pneumonia

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14
Q

contraindications for emesis

A
  • recumbent/unconscious/no gag/seizure
  • caustic (acid/alkali/bleach)
  • petroleum
  • detergents
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15
Q

How can emesis be induced?

A
  • apomorphine (0.02-0.04mg/kg IV/SC)
  • xylazine CATS (0.44 mg/kg IM/SC)
  • medetomidine CATS (5-20mcg/kg)
  • 3% hydrogen peroxide (1-5ml/kg dog, 10ml/kg cat)
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16
Q

INdications for gastric/colonic lavage?

A
  • ingestion
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17
Q

contraindications for gastric/colonic lavage?

A

caustic

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18
Q

complications of gastric/colonic lavage?

A
  • aspiration pneumonia (cuff ET tube!)

- hypothermia

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19
Q

Outline how to perform a gastric lavage

A
  • GA (ET tube)
  • pass stomach tube (muzzle -> last rib)
  • lavage 10-20ml/kg water, slosh around, empty
  • repeat until no more contents retrieved
  • 3 sided lavage (left, right and sternal)
  • remove tube while kinking to prevent leakage into oesophagus
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20
Q

Indications for activate charcoal?

A
  • toxins that will bind to it!

- enterohepatic metabolism

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21
Q

Contraindications for activated charcoal/

A
  • recumbent/unconscious/no gag/seizure
  • toxins that don’t bind to AC
  • ethylene glycol
  • alcohol
  • alkali
  • petroleum
  • heavy metals
  • xylitol
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22
Q

complicatiosn of activate charcoal (AC)

A
  • aspiration pneumonia

- if containing sorbitol -> dehydration, only use once

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23
Q

how is activated charcoal administered?

A
  • 1-2g/kg PO
  • food.syruinge
  • q4hrs for 4 doses or until feaces black
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24
Q

Indications for diuresis?

A
  • renal excretion of toxins

- nephrotoxic

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25
Q

contraindications for diuresis?

A
  • risk of fluid overload
  • anuric/oligouric
  • cardiac disease
  • pulmonary disease
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26
Q

How is diuresis carried out?

A
  • 2-3x maintainance rate IVF
  • 48-72hours
    > If anuric/oligouric
  • furosemide (0.5-2mg//kg q2-8hours IV, 2-5mcg/kg/min)
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27
Q

Indications for dermal decontamination?

A
  • dermal toxins (permethrin, engine oil, oil on birds)
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28
Q

contraindications for dermal decontamination?

A
  • hypothermia

- sedation

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29
Q

How can dermal decontamination be carried out?

A
  • clip

- wash with vegetable oil and washing up liquid

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30
Q

Indications for intralipid?

A
  • lipophilic toxins (Log P >1)

- local anesthetics, ivermectin, permethrin, baclofen, marijuana, mycotoxin, TCA, B-blockers, Ca channel blockers

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31
Q

Adverse effects of intralipid use?

A
  • lipaemia
  • pancreatitis
  • hypersensitivity
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32
Q

How is intralipid given?

A
  • 1.5ml/kg over 5 mins
  • CRI 0.25ml/kg/min
  • repeat q1-4hours
  • check serum for lipaemia
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33
Q

Antidote of opioids

A

Naloxone

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34
Q

Antidote of a2 ags

A

Atimpamezole

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35
Q

Antidote of benzos

A

Flumazenil

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36
Q

Antidote of ethylene glycol

A

Ethanol / 4-methylpyrazole

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37
Q

Antidote of paracetamol

A

N-acetylcysteine

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38
Q

Antidote of NSAIDs

A

misoprostol (Sythetic PGs)

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39
Q

Antidote of anticoagulant rodetnacide

A

Vitamin K

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40
Q

What is dialysis indicated for?

A
  • ethylene glycol
  • baclofen
  • paracetamol
  • aminoglycosides
  • ethanol
  • mushrooms
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41
Q

Outline emergency tx protocol for seizures

A
  1. neuro (seizure control)
    - Diazepam, propofol
  2. CV (shock)
    - 20ml/kg bolus IVF
  3. respiratory
    - flow by O2/intubate
  4. temperature (if high)
    - cool to 39.3
    - running water. fan, cold surface
42
Q

Ddx for seizures and tremor

A
  • metaldehyde (snail pellets)
  • mycotoxin
  • theobromine (chocolate, caffeine)
  • permethrin (topical flea tx, only tox to cats)
  • recreational drugs
  • lead
  • OPs/carbamates
43
Q

What is the commonest cause of death by toxins in dogs?

A
  • metaldehyde toxicosis (slug pellets)

- LD50 100-1000mg/kg variable

44
Q

Tx for metaldehyde toxicosis specifically?

A
  • if moderate signs, + activated charcoal left in stomach after
  • oral activated charcoal avoided in conscious animals d/t risk of rapid onset convulsions
    > control of convulsions and hyperthermia
  • diazepam, barbituates, propofol +- midazolam, methocarbamol
    [metaldehyde NOT lipophilic, log P = 0.12]
  • haemodialysis been shown to remove metaldehyde from canine plasma IN VITRO
45
Q

Tx protocol for metaldehyde induced seizures (CAse 1)?

A
  • gastric lavage and enema
  • phenobarbitone + propofol CRI
  • repeat enema as passing blue feaces
  • IVF: maintainance and ongoing losses
  • 12hrs later weaned off propofol
  • ambulatory with tremors- activated charcoal q4hrs until feaces black
46
Q

What are mycotoxins?

A
  • fungal metabolites -> toxicity in humans and animals

- tremorgenic mycotoxins present in some mouldy foods, silage and compost

47
Q

Potential signs of mycotoxicity?

A
  • V+
  • ataxia
  • hyperaesthesia
  • mild hypersalivation
  • generalised tremors
48
Q

Tx mycotoxin

A
  • apomorphine
  • activated charcoal
  • diazepam
  • cool IV fluids
  • more diazepam as tremors recurred
  • resolved ~18 hours, 8hrs after last dose of diazepam
49
Q

What is the toxic component of chocolate?

A
  • theobromine
50
Q

What levels of chocolate ingestion are toxic to dogs?

A
  • toxic > 20mg/kg
  • severe signs @ 40-50mg/kg
  • seizures @ 60 mg/kg
    > dark chocolate tx for >3.5g/kg
    > milk chocolate tx for > 14g/kg
    > white chocolate contains ONLY COCO BUTTER so not toxic (but ^ sugar so still bad!)
51
Q

Clinical signs of theobromine ingestion

A
  • VD+
  • PD
  • salivation and dehydration
  • CNS/myocardial stimulation - trmor, convulsions, tachycardia, hypertension and arrhythmias
  • renal failure
  • fatal cases d/t severe convulsions/circulatory failure
52
Q

Tx theobromine ingestion?

A
  • emesis
  • activate charcoal
  • hydration
  • benzos for CNS stimulation
  • lidocaine/b blocker for tachycardia/arrhythmia
53
Q

Caue of permethrin toxicity?

A

Use of dog products on cats
- alters kinetics of nerve membranes -> repetitive discharge of membrane potentials +- inhibition of GABA receptors -> hyperexcitability of nervous tissues

54
Q

How long does permethrin toxicity take to occour? CLinical signs?

A
  • 1-3hrs, sometimes up to 36 hours after application

- duration of effects 1-3d (

55
Q

Tx permethrin in cats

A
  • diazepam
  • pentobarbital
  • propofol
  • mathocarbamol (centrally acting skeletal mm relaxant, can be effective if benzos fail)
  • intravenous lipd infusion
56
Q

Clues that indicate collapse d/t anaemia and initial emergency tx.

A
  1. CV: 2-ml/kg IVF bolus
  2. PCV/TS - 25%, 40g/L - anaemic
  3. blood smear - non-regenerative anaemia, no haemolysis, platelets ok
  4. AFAST ultrasound - peritoneal effusion
  5. Abdominocentesis - PCV 30%, TS35g/L
  6. PT >45s (normal
57
Q

Ddx for anaemia 2* to toxins

A 
> coagulopathy 
- anticoagulant rodenticide 
- coagulopathy 2* to hepatopathy (xylitol) 
> haemolysis 
- paracetamol (cats)
 - onion/garlic
58
Q

Egs of rodenticide anticoagulants

A
  • bromadiolone, brodifacoum, difenacoum, flocoumafen (2nd gen)
  • stronger strength available for professional use, normally ~0.005% strength
59
Q

What is the pathogenesis of anticoagulatns?

A

Prevents production of active vitamin K

- active vit K needed for clotting factors

60
Q

When are peak plasma levels of anticoagulant rodenticide seen?

A
  • vary mins-hrs

- plasma elimination T1/2 = 14hrs for warfarin, = 6d for brodifacoum

61
Q

Are clinical effects of anticoagulant rodenticide common? What are they?

A

No uncommon
- clotting factors t1/2 = 6-16 hours so delay between exposure and onset of clinical signs (~27-72hrs)
> clinical signs:
- ^ PT time
- haemorrhage
- bruising
- bleeding gums, nose, GI tract and wounds
- may present as dyspnoea, weakness and lethargy

62
Q

What does tx threshold for anticoagulant rodenticide ingestion depdend on? Eg doses?

A
  • active ingredient
    > difenacoum 0.005% 100g/kg ingestion threshold
    > brodifacoum 8g/kg
    > Bromadialone 7g/kg
    > flucoumafen 0.005% 0.15g/kg ingestion threshold!
63
Q

If tx is required for anticoagulant rodenticide toxicosis, what is it?

A
  1. decontamination
64
Q

Tx regime for vit K?

A
  • until PT normalises 2-5mg/kg IV/SC/IM daily
  • once PT normalised orally for ~3 weeks (2-5mg/kg divded doses)
  • check PT 1-3d after discontinuing tx
    > whole blood/plasma transfusions may be required
65
Q

Other names for paracetamol?

A
  • acetaminophen

- APAP

66
Q

Why does paracetamol toxicity occour? Which species especially?

A
  • saturation of metabolic pathways, toxic metabolite conjugated by glutathione (promptly depleted)
  • CATS lack metabolic capacity to detoxify paracetamol
67
Q

Clinical signs of paracetamol tox?

A 
> early  4-24hrs 
- facial and paw oedema
- V+ 
- depression 
- dark brown blood (methaemoglobinaemia) 
> 24hrs + 
- severe methaemoglobinaemia
- hepatic necrosis 
> cyanosis and methaemoglobinaemia do not respond to oxygen therapy
68
Q

Threshold for tx paracetamol tox in cats and dogs. Tx?

A

Dogs 150mg/kg
Cats 20mg/kg
- emesis (optimal

69
Q

Ddx for renal signs with toxin ingestion?

A
  • ethylene glycol
  • NSAIDs
  • aminoglycosides
  • Lily (cats)
  • Grapes/raisins (dogs)
70
Q

Potential renal signs seen with toxicosis?

A
  • PCV/TS 45% 67g/l

- biochem urea 22mml/l (3-10 norm), creatinine 550umol/l (

71
Q

Most common NSAIDs causing renal toxicosis? How do vet and human NSAIDs differ?

A
  • ibuprofen
  • naproxen, diclofenac, cerprofen, meloxicam, others
  • CoX-2 specific inhibitors used in vet medicine so human drugs potentially dangerous
72
Q

Pathogenesis of NSAID toxicosis?

A
  • inhibition of COX enzymes
  • COX 2 inflammatory response
  • sustained reduction of inflammatory response
  • toxicity likely d/t COX-1 inhibition
73
Q

Early signs of NSAID toxicity?

A
  • GI eroisuin, ulceration and perforation possible
  • VD+ with blood
  • rarely CNS signs (ataxia, lethargy, drowsiness) w/ large doses >400mg/kg ibuprofen
74
Q

Late signs of NSAID toxicity

A
  • renal failure

- hepatic damage

75
Q

Which flowers are potentially nephrotoxic?

A

Lilies - true lily (liliaceae) and day lily (hemerocallidaceae)
- renal failure in cats

76
Q

Which parts of the lily are toxic? Signs?

A 
All parts (v smalll amount needed for clinical signs) 
- signs: 
- GI Iirritation 
- PU
- dehydraion 
- renal failure 
\+- seizures if severe
77
Q

Tx and prognosis of lily toxicity?

A 
Aims
> reduce absorption 
- emesis and/or activated charcoal 
> enhance renal perfusion 
- IVF min 48hours 
> once renal failure has occurred txl limited
> prognosis good if tx started before onset of renal impariment 
> prognosis guarded if renal failure
78
Q

What cuases chewing gum to be toxic? Pathogensis?

A

> Xylitol

  • naturally occourring sugar alcohol in fruit and veg
  • rapid and potent stimulator of INSULIN in dogs dose-dependent)
  • liver damage (unknown mechanism)
79
Q

Where else is xylitol found other than chewing gum?

A
  • highest in gum other than protein bars (higher)
  • mints
  • protein bars massive amounts
  • strepsils
  • nurofen
  • nicorette gum
  • other things
80
Q

Tx xylitol toxicosis? Monitoring?

A
  • aggressive
  • tx for >0.05g/kg (50mg/kg)
  • gastric decontamination
    > monitoring
  • baseline glucose, K, Ph, bilirubin, LFTs and clotting tests
  • glucose conc q1-2hrs min 12 hrs
  • recheck other tests q24hrs min 72hrs
    > hypoglycaemia tx
  • frequent small meals and oral sugar for 8-10hrs
  • glucose/dextrose severe cases
  • ECG monitoring d/t risk of hypokalaemia induced arrythmias
    > hepatotoxicity tx
  • immediate dextrose tx
  • Hepatoprotectants: S-adenosyl L-methione (“Denosyl”) or acetylcystene
81
Q

Ddx for hepatotoxcity?

A
  • xylitol
  • mushroom
  • paracetamol
82
Q

Clinical signs of bendiocarb Ficam W fumigation toxicity?

A
  • mod ataxia
  • abnormal lung sounds
  • tachycardia
  • pupils ____
  • bowel sounds____
83
Q

Tx bendiocarb potential tox

A
  • diazepam and attropine
84
Q

Toxic doses of Ibuprofen (most common toxicosis)

A

10mg/kg

85
Q

Toxic doses of Carprofen (most common vet NSAID)

A

40mg/kg

86
Q

Toxic doses meloxicam?

A

oral >1mg/kg, sc 0.2mg/kg

87
Q

How can NSAID decontamination be performed?

A
  • emesis optimal
88
Q

How can gastric ulceration associated with NSAID use be minimised?

A 
> 10mg/kg+ ibuprofen, >150mg/kg carprofen, >2mg/kg oral or >0.2mg/kg SC meloxicam
> H2 -R antagonists
- Cimetidine (Tagamet)
- Ranitidine (Zantac)
- Famotidine (Pepcid) 
> Proton pump inhibitors 
- Omeprazole
> Ulcer healing/coating agent
- Sucralfate (Antepsin) 
> PG supplements 
- Misoprostol (Cytotec)
89
Q

Maintaining renal function when using NSAIDs?

A
  • fluid therapy
    > oral
    > IVF maintainance for 24-48hrs
  • guided by renal function tests
90
Q

Tx and monitoring of renal toxicosis with NSAIDs

A 
Tx
> Diuresis
- IVF 2-3x maintainance 
- furosemide if anuric despite IVF
> Gastroprotection 
- omeprazole 1mg/kg IV
> antiemetic
- Maropitant 1mg/kg SC
Monitoring
- urine output 
- body weight 
- urea/creat
- potassium
- ECG
91
Q

Mechanism of toxicity of ethylene glycol?

A
  • rapid absorption (cats peka plasma conc eg. glycoaldehyde, glycolic acid (rate limiting step, acidosis and ^ levels in urine indicative) glyoxilic aid, oxalic acid
92
Q

Diagnostics results with ethylene glycol toxicity?

A
  • azotaemia and hyperglycaemia (inhibition of glucose metabolism)
  • ^ osmolality (normal 280-310mOsm/kg, ^ 60mOSm/kg)???
  • ^ anion gap (normal 10-12mEg/L ^ to 40mEg/L)
  • acidosis (blood
93
Q

How can ethylene glycol tox be confirmed? Does a negative result r/o?

A
  • urine and other contaminated tissue fluoresces under woods lamp within 6 hrs
  • negative does not r/o tox
94
Q

Tx of ethylene glycol toxicosis?

A

> early Dx and aggressive tx!!
- gastric decontamination
- confirm dx with urinalysis
- tx to block action of alcohol dehydrogenase
ethanol therapy [most common] or fomepizole EARLY
- IV ethanol (pharmaceutical grade) or vodka
- 5% solution CRI 5ml/kg/hr for 48hrs +
OR - 5ml/kg 20% ethanol in saline IV q6hrs for 5 doses then q8hrs for 4 doses
- oral loading dose 2.4ml/kg 40% solution vodka/whisky [equated to 750mg/kg] 1st hr
- then 0.5ml/kg/hr [equates to 150mg/kg/hr]

95
Q

Side effects of alcohol tx of ethylene glycol tox?

A
  • significant CNS depression and hypothermia +- hypoglycaemia
96
Q

Which toxins can cause seizure/tremor?

A
  • metaldehyde
  • mycotoxin
  • theobromine
  • permethrin
  • lead
  • organophosphate
  • recreational drugs
97
Q

Which toxins can cause anaemia? By what mechanisms?

A 
> coagulation
- rodenticide
- hepatotxins
> haemolysis
- paracetamol (cats) 
- onion/garlic
- heavy metals
98
Q

Which toxins affect the renal system

A
  • ethylene glycol
  • NSAIDs
  • aminoglycosides
  • lilies (cats)
  • raisins/grapes (dogs)
99
Q

Which toxins affect hepatic function?

A
  • xylitol (also -> hypoglycaemia)
  • cycad
  • mushroom
  • paracetamol
100
Q

Most important point of tx in toxicology?

A

tx the patient - heart, lung, brain

- also many toxins cause GI signs

POS 2 (28 decks)

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