Make sure to winterize your brain! Cliff notes for Antifreeze toxicosis
By: Dr. Garret Pachtinger, DACVECC
Board-Certified Critical Care Specialist
Veterinary Specialty & Emergency Center
Ethylene glycol is a common and unfortunately life threatening hazard to our small animal patients. Ethylene glycol is a sweet, odorless, water-soluble chemical with many common household uses. It may be found in antifreeze designed for cars, de-icing agents, windshield washer fluids, home solar units, portable chemical toilets, and some household heating components. While the compound itself is not toxic, it is metabolized into many other components (i.e., glycolic acid, oxalate, and aldehyde) that are extremely toxic and potentially fatal to our small animal patients.
Antifreeze is rapidly absorbed following ingestion and metabolized with a half-life of 3 to 5 hours. While specific toxic doses have not been established, the lethal dose is relatively small (4.4 to 6.6 ml/kg in dogs; 1.4 ml/kg in cats).
Clinical signs generally progress through three stages, although some patients may skip a stage, owners may miss a stage, or the stages may overlap.
Stage 1: Gastrointestinal upset (vomiting, diarrhea) and ataxia. Owners often describe their pet as being drunk during this stage. This first stage typically begins within 30 minutes of ingestion and lasts approximately 12 hours.
Stage 2: As time progresses, the patient develops cardiovascular and pulmonary abnormalities due to the (metabolic) acidosis and electrolyte abnormalities which develop as a result of the metabolism of the toxin. The second stage is classified by signs including tachypnea and tachycardia, lasting approximately 24 hours after ingestion.
Stage 3: The third stage is characterized by oliguric to anuric renal failure and usually occurs within 24 to 72 hours after ingestion.
Diagnosis of ethylene glycol intoxication is based on the following:
- History of ingestion/exposure
- Increased anion gap, metabolic acidosis
- Elevated serum BUN and creatinine (azotemia)
- Elevated phosphorus and potassium
- Decreased ionized calcium
- Isosthenuria (1.008 to 1.012)
- Presence of calcium oxalate crystalluria (usually within 3-5 hours of ingestion)
- monohydrate form (prism) seen more commonly than dihydrate form (envelope or maltese cross)
- Urine may fluoresce under Wood’s lamp
- Detection of EG or metabolite (glycolic acid)
- Ultrasonography can be a very useful diagnostic tool as well as the kidneys have a classic “halo effect” on ultrasound, specifically an increase in cortical and medullary echogenicity with less echogenicity at the corticomedullary junction.
- Decontamination: Patients presented within 8 hours following ingestion of ethylene glycol have the greatest chance of survival. If the patient presents within 1 hour of ingestion and the patient is asymptomatic, inducing vomiting can be considered. Although not contraindicated, activated charcoal has limited benefit for these cases as it is ineffective in adsorbing this toxin.
- “Antidotes”: Administration of compounds that interfere with or delay formation of the metabolic by-products are also useful. Examples include ethanol and fomepizole.
- H2 blockers (famotidine, raniditine, cimetidine, nizatidine)
- Proton pump inhibitor (omeprazole, esomeprazole, pantoprazole)
- Antiemetics (maropitant, ondasetron, dolasetron)
- Antiepileptics if seizure behavior is present (Benzodiazepines, Barbiturates, anesthetics)
- Fluid therapy: To prevent further kidney damage, maintaining acid-base balance, correct electrolyte imbalances and promote diuresis.
Dr. Garret Pachtinger is a Board-Certified Emergency and Critical Care Specialist at the Veterinary Specialty & Emergency Center. The Veterinary Specialty & Emergency Center operates state-of-the-art emergency and specialty veterinary hospitals that are open 24/7/365 in both Levittown PA and Philadelphia PA. For more information about our world-class emergency and specialty care, please visit VSEC on the web at www.VSECVET.com.