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Toxicology Flashcards

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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
contraindications for diuresis?
- risk of fluid overload - anuric/oligouric - cardiac disease - pulmonary disease
26
How is diuresis carried out?
- 2-3x maintainance rate IVF - 48-72hours > If anuric/oligouric - furosemide (0.5-2mg//kg q2-8hours IV, 2-5mcg/kg/min)
27
Indications for dermal decontamination?
- dermal toxins (permethrin, engine oil, oil on birds)
28
contraindications for dermal decontamination?
- hypothermia | - sedation
29
How can dermal decontamination be carried out?
- clip | - wash with vegetable oil and washing up liquid
30
Indications for intralipid?
- lipophilic toxins (Log P >1) | - local anesthetics, ivermectin, permethrin, baclofen, marijuana, mycotoxin, TCA, B-blockers, Ca channel blockers
31
Adverse effects of intralipid use?
- lipaemia - pancreatitis - hypersensitivity
32
How is intralipid given?
- 1.5ml/kg over 5 mins - CRI 0.25ml/kg/min - repeat q1-4hours - check serum for lipaemia
33
Antidote of opioids
Naloxone
34
Antidote of a2 ags
Atimpamezole
35
Antidote of benzos
Flumazenil
36
Antidote of ethylene glycol
Ethanol / 4-methylpyrazole
37
Antidote of paracetamol
N-acetylcysteine
38
Antidote of NSAIDs
misoprostol (Sythetic PGs)
39
Antidote of anticoagulant rodetnacide
Vitamin K
40
What is dialysis indicated for?
- ethylene glycol - baclofen - paracetamol - aminoglycosides - ethanol - mushrooms
41
Outline emergency tx protocol for seizures
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
Ddx for seizures and tremor
- metaldehyde (snail pellets) - mycotoxin - theobromine (chocolate, caffeine) - permethrin (topical flea tx, only tox to cats) - recreational drugs - lead - OPs/carbamates
43
What is the commonest cause of death by toxins in dogs?
- metaldehyde toxicosis (slug pellets) | - LD50 100-1000mg/kg variable
44
Tx for metaldehyde toxicosis specifically?
- 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
Tx protocol for metaldehyde induced seizures (CAse 1)?
- 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
What are mycotoxins?
- fungal metabolites -> toxicity in humans and animals | - tremorgenic mycotoxins present in some mouldy foods, silage and compost
47
Potential signs of mycotoxicity?
- V+ - ataxia - hyperaesthesia - mild hypersalivation - generalised tremors
48
Tx mycotoxin
- apomorphine - activated charcoal - diazepam - cool IV fluids - more diazepam as tremors recurred - resolved ~18 hours, 8hrs after last dose of diazepam
49
What is the toxic component of chocolate?
- theobromine
50
What levels of chocolate ingestion are toxic to dogs?
- 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
Clinical signs of theobromine ingestion
- 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
Tx theobromine ingestion?
- emesis - activate charcoal - hydration - benzos for CNS stimulation - lidocaine/b blocker for tachycardia/arrhythmia
53
Caue of permethrin toxicity?
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
How long does permethrin toxicity take to occour? CLinical signs?
- 1-3hrs, sometimes up to 36 hours after application | - duration of effects 1-3d (
55
Tx permethrin in cats
- diazepam - pentobarbital - propofol - mathocarbamol (centrally acting skeletal mm relaxant, can be effective if benzos fail) - intravenous lipd infusion
56
Clues that indicate collapse d/t anaemia and initial emergency tx.
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
Ddx for anaemia 2* to toxins
``` > coagulopathy - anticoagulant rodenticide - coagulopathy 2* to hepatopathy (xylitol) > haemolysis - paracetamol (cats) - onion/garlic ```
58
Egs of rodenticide anticoagulants
- bromadiolone, brodifacoum, difenacoum, flocoumafen (2nd gen) - stronger strength available for professional use, normally ~0.005% strength
59
What is the pathogenesis of anticoagulatns?
Prevents production of active vitamin K | - active vit K needed for clotting factors
60
When are peak plasma levels of anticoagulant rodenticide seen?
- vary mins-hrs | - plasma elimination T1/2 = 14hrs for warfarin, = 6d for brodifacoum
61
Are clinical effects of anticoagulant rodenticide common? What are they?
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
What does tx threshold for anticoagulant rodenticide ingestion depdend on? Eg doses?
- active ingredient > difenacoum 0.005% 100g/kg ingestion threshold > brodifacoum 8g/kg > Bromadialone 7g/kg > flucoumafen 0.005% 0.15g/kg ingestion threshold!
63
If tx is required for anticoagulant rodenticide toxicosis, what is it?
1. decontamination
64
Tx regime for vit K?
- 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
Other names for paracetamol?
- acetaminophen | - APAP
66
Why does paracetamol toxicity occour? Which species especially?
- saturation of metabolic pathways, toxic metabolite conjugated by glutathione (promptly depleted) - CATS lack metabolic capacity to detoxify paracetamol
67
Clinical signs of paracetamol tox?
``` > 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
Threshold for tx paracetamol tox in cats and dogs. Tx?
Dogs 150mg/kg Cats 20mg/kg - emesis (optimal
69
Ddx for renal signs with toxin ingestion?
- ethylene glycol - NSAIDs - aminoglycosides - Lily (cats) - Grapes/raisins (dogs)
70
Potential renal signs seen with toxicosis?
- PCV/TS 45% 67g/l | - biochem urea 22mml/l (3-10 norm), creatinine 550umol/l (
71
Most common NSAIDs causing renal toxicosis? How do vet and human NSAIDs differ?
- ibuprofen - naproxen, diclofenac, cerprofen, meloxicam, others - CoX-2 specific inhibitors used in vet medicine so human drugs potentially dangerous
72
Pathogenesis of NSAID toxicosis?
- inhibition of COX enzymes - COX 2 inflammatory response - sustained reduction of inflammatory response - toxicity likely d/t COX-1 inhibition
73
Early signs of NSAID toxicity?
- GI eroisuin, ulceration and perforation possible - VD+ with blood - rarely CNS signs (ataxia, lethargy, drowsiness) w/ large doses >400mg/kg ibuprofen
74
Late signs of NSAID toxicity
- renal failure | - hepatic damage
75
Which flowers are potentially nephrotoxic?
Lilies - true lily (liliaceae) and day lily (hemerocallidaceae) - renal failure in cats
76
Which parts of the lily are toxic? Signs?
``` All parts (v smalll amount needed for clinical signs) - signs: - GI Iirritation - PU - dehydraion - renal failure +- seizures if severe ```
77
Tx and prognosis of lily toxicity?
``` 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
What cuases chewing gum to be toxic? Pathogensis?
> Xylitol - naturally occourring sugar alcohol in fruit and veg - rapid and potent stimulator of INSULIN in dogs dose-dependent) - liver damage (unknown mechanism)
79
Where else is xylitol found other than chewing gum?
- highest in gum other than protein bars (higher) - mints - protein bars massive amounts - strepsils - nurofen - nicorette gum - other things
80
Tx xylitol toxicosis? Monitoring?
- 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
Ddx for hepatotoxcity?
- xylitol - mushroom - paracetamol
82
Clinical signs of bendiocarb Ficam W fumigation toxicity?
- mod ataxia - abnormal lung sounds - tachycardia - pupils ____ - bowel sounds____
83
Tx bendiocarb potential tox
- diazepam and attropine
84
Toxic doses of Ibuprofen (most common toxicosis)
10mg/kg
85
Toxic doses of Carprofen (most common vet NSAID)
40mg/kg
86
Toxic doses meloxicam?
oral >1mg/kg, sc 0.2mg/kg
87
How can NSAID decontamination be performed?
- emesis optimal
88
How can gastric ulceration associated with NSAID use be minimised?
``` > 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
Maintaining renal function when using NSAIDs?
- fluid therapy > oral > IVF maintainance for 24-48hrs - guided by renal function tests
90
Tx and monitoring of renal toxicosis with NSAIDs
``` 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
Mechanism of toxicity of ethylene glycol?
- rapid absorption (cats peka plasma conc eg. glycoaldehyde, glycolic acid (rate limiting step, acidosis and ^ levels in urine indicative) glyoxilic aid, oxalic acid
92
Diagnostics results with ethylene glycol toxicity?
- 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
How can ethylene glycol tox be confirmed? Does a negative result r/o?
- urine and other contaminated tissue fluoresces under woods lamp within 6 hrs - negative does not r/o tox
94
Tx of ethylene glycol toxicosis?
> 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
Side effects of alcohol tx of ethylene glycol tox?
- significant CNS depression and hypothermia +- hypoglycaemia
96
Which toxins can cause seizure/tremor?
- metaldehyde - mycotoxin - theobromine - permethrin - lead - organophosphate - recreational drugs
97
Which toxins can cause anaemia? By what mechanisms?
``` > coagulation - rodenticide - hepatotxins > haemolysis - paracetamol (cats) - onion/garlic - heavy metals ```
98
Which toxins affect the renal system
- ethylene glycol - NSAIDs - aminoglycosides - lilies (cats) - raisins/grapes (dogs)
99
Which toxins affect hepatic function?
- xylitol (also -> hypoglycaemia) - cycad - mushroom - paracetamol
100
Most important point of tx in toxicology?
tx the patient - heart, lung, brain | - also many toxins cause GI signs

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