Environmental / Household Products

Question 1

Antifreeze/ Ethylene Glycol

Answer 1

*Methanol can be found in other antifreeze products that doesn’t have ethylene glycol
-also found in windscreen wiper fluid
-signs of intoxication:
~GI upset, drooling, inebriation, ataxia, dyspnea, and arrhythmia
~death from respiratory failure , hypothermia, hypoglycemia or acidosis

• TX:
• IVF
• thermoregulation
• respiratory support
• manage acidosis and hypoglycemia
• diazepam for seizures
• Recovery:
• usually within 24-36 hours

*Ethylene Glycol
-CNS depression
-GI irritation
-life threatening effects are from metabolites when broken down
-metabolism in the liver where alcohol dehydrogenase converts it to glycoaldehyde and organic acid
-glycoaldeyde converts to glycolic acids then to glycoxylate then to oxalates=combines with calcium to become calcium oxalate crystals
~deposited into the body primarily in the kidneys

*Clinical effects:
Stage 1: neurological phase
-CNS depression within 30 minutes of ingestion
-ataxia, depression
-as serum osmolality increases =polydipsia and polyuria
-this phase often missed by owners as it quickly passes

Stage 2:acidotic phase

• increase in acidic metabolites
• usually lasts 6 to 24 hours after ingestion
• cardiovascular effects: tachycardia, tachypnea, pulmonary edema
• seizures possible
• high anion gap (40-50mEq/L)
• Hypoclacemia (as it binds with oxalic acid)
• hyperglycemia
• increased renal enzymes
• hyperkalemia

Stage 3: renal failure

• as early as 24 hours post ingestion
• most likely 24-72 hours
• signs: anorexia, vomiting, abdominal pain, oral ulceration and anuria
• presence of calcium oxalate crystals in urine, but absence of them does not rule out intoxication
• No available test
• Kacey test will be positive for alcohol so don’t use alcohol in fur when getting sample
• Preventing the metabolism of ethylene glycol into toxic metabolites is the key to saving this patient
• must decontaminate within 2 hours of ingestion
• AC not helpful
• Ethanol as antidote
  
  • competes with ethylene glycol for active site of alcohol dehydrogenase
  • administer 30% ethanol IV and titrated to stupor
• disadvantage : CND depression and exacerbation of osmotic diuretics and plasma hyperosmolality
• 4-methylpyrazone (4-MP, fomepizole) is a specific and more effective inhibitor of alcohol dehydrogenase
• few to no adverse effects
• Cats
• 75% recovery if treated within 3 hours of ingestion with 4MP
• 100% mortality rate if Tx delayed by 1 hour

Question 2

Anticoagulant Rodenticides

Answer 2

• First generation
• coumarin, warfarin, indandione compounds
• Newer generation
• brodifacoum, bromadiolone and diphacinone
• more toxic and longer lasting

*inhibits production of enzyme vitamin K epoxide reductase so that vitamin K cannot be regenerated or recycled in the body
-this then prevents vit K-dependent coagulation factors (Factors II, VII, IX and X)
-Extrinsic pathway will show an issue first, as factor VII has a half life of 6.2 hours
-PT as a test of this pathway will be elevated
-PIVKA (proteins induced in vit K antagonism) tests can be sent to lab but no more sensitive than PT test
-Signs: not noted until 3-7 days after exposure
: lethargy, anorexia, exercise intolerance
-Warfarin: 0.5mg/kg
- second generation: 0.02mg/kg + much longer duration of action
-typically bleeding occurs in lungs or body cavity
-Tx: decontamination within 4 hours
: AC once off as repeat doses not proven to be useful
: Vitamin K (phytonadione) PO if possible with food to help with absorption
: transfusion with whole blood or FFP to correct anaemia and coagulopathy
: thoracocentesis only minimally and only if patient’s respiratory is clinically impaired
: clotting time testing to be done prior to administration of Vit K as it wil alter results
: Test at baseline and 48 and 72 hours post ingestion to monitor effects
: administer vitamin K for 14 days with 1st generation products and 30 days with the 2nd generation
: PT should be run 48 hours after the last dose to ensure no bleeding will occur or tx can be extended

Question 3

Bromethalin

Answer 3

*rodenticide developed for use against warfarin resistant rodents
*causes uncoupling of oxidative phosphorylation in CNS and liver mitochondria
*results in decrease in ATP and then causes ATP-dependent transport pumps to not function
*this causes water to move into the cells due to build up of intracellular sodium
-leads to cerebral edema
-increased ICP
-signs dependent on dose ingested
*high dose ingestion: muscle tremors and seizures, hyperexcitibility, hyperthermia
*low dose: manifest in 1-3 days
: hind limb ataxia, paresis or paralysis
: CNS depression
*management:
-decontamination via anesthesia and gastric lavage
-repeated dose of AC for 48 hours due to recirculation
-aim is to control seizures and supportive care
*cerebral perfusion pressure should be maintained and oxygen supplementation advised
*mannitol to reduce cerebral edema
*elevate patient’s head at 15-30degrees incline
-NO PRESSURE on jugular veins
*maintain normocapnia (normal arterial CO2 ~40mmHg)
*prognosis is poor with severe signs

Question 4

Cholecalciferol

Answer 4

• Vitamin D3 rodenticide
• works by activation to calcitriol which increases serum calcium levels by increasing intestinal, bone and tubular reabsorption of calcium
• leads to renal failure and cardiac arrhythmias due to metastatic calcification
• Signs:
• polyuria
• polydipsia
• lethargy
• anorexia
• vomiting
• AKI from hypercalcemia
• toxicity:
• dose and age dependent
• younger animals more at risk
• Tx:
• decontamination in less than 4 hours
• emesis and repeat AC dose every 8-12 hours
• IVF 0.9% NaCl to induce calciuresis
• furosemide to enhance Ca loss
• pamidronate disodium is a biphosphonate that inhibits osteclastic with in 48 hours of administration = can be obtained from human hospital but is expensive
• Salmon calcitonin: induces calciuresis and reduce resorption of calcium from bone, but have a risk of anaphylaxis

Question 5

Zinc phosphide

Answer 5

• rodenticide
• forms phosphine gas in acidic conditions (i.e. stomach)
• phosphide gas is highly toxic
• odour of rotten fish or acetylene
• zinc phosphide
• inhibits oxidative phosphorylation
• interrupts ATP production in mitochondria
• resulting in cell death, peroxidation and cellular oxidative damage
• lowest reported lethal dose:
• 40mg/kg
• rodents tend to die in the open and dogs/cats eat them
• Clinical signs:
• rapid
• vomiting
• anorexia
• depression
• rapid, deep, wheezy respiration
• vomiting with or without blood
• ataxia, weakness, hypoxia
• zinc phosphide can be detected chemical,but degrades rapidly
• TX:
• rapid decontamination with emesis, lavage, AC
• increasing pH with sodium bicarbonate will slow hydrolysis into gas
• IVF support essential
• Avoid personnel or owners to phosphine gas present in vomitus
• Good prognosis when decontamination occurs early
• Guarded when Clinical signs already present