Exposure (known or suspected) warrants immediate veterinary emergency assessment! Most exposures occur in the fall and spring

Antidotes can be administered to your pet to help prevent permanent kidney damage caused by ethylene glycol

Prognosis directly correlates to the amount of ethylene glycol ingested and time of treatment administrated

Our emergency team is available 24 hours daily, every day, to treat any type of emergency situation, including antifreeze toxicity

What is Ethylene Glycol Toxicity?

• Ethylene glycol is a common widely used automotive antifreeze/coolant solution. It is also found in industrial solvents, rust removers, color film processing fluids, taxidermist preservation solutions and heat exchange fluids.
• Exposure :
  • Exposure (known or suspected) warrants immediate veterinary emergency assessment! Most exposures occur respectively in the fall and spring.   Behavior such as roaming may also increase the chances of exposure.

Mode of Action

• Ethylene glycol is palatable to pets because of its sweet smell and taste. Once ingested, it is rapidly absorbed by the gastrointestinal tract and is metabolized to oxalic acid. Oxalic acid combines with calcium to form calcium oxalate crystals, which precipitate into the microscopic structures within the kidneys. The crystallization of these structures causes acute renal (kidney) failure. Crystals also flood the microvasculature of other organ systems setting up for multi-organ system dysfunction.   Oxalic acid further creates a severe, life threatening metabolic acidosis (causing respiratory and cardiovascular signs), and can cross the blood brain barrier leading to neurological abnormalities and death.
• Maximum blood concentration usually is attained by 1-4 hours post a single ingestion. Within 16-24 hours post exposure, nearly all the ethylene glycol has been metabolized or excreted in the urine.

Clinical Signs

• Diagnosis is difficult to make on clinical signs alone.   Owners may first notice non specific clinical signs, if exposure to ethylene glycol is not directly witnessed.   These signs may include anorexia, lethargy and vomiting.
• Signs related to exposure often follow this staged pattern:
  • Stage I : 30 minutes to 4 hours post ingestion. Signs are related to neurological dysfunction and include mild depression, drunken gait (ataxia), knuckling, in coordination, stumbling, hyper-excitability, stupor, increased thirst or urination, protrusion of third eyelids.
  • Stage II : 4-24 hours post ingestion.   Cardio-respiratory signs associated with metabolic acidosis including increased heart rate and increased respiratory rate or effort, low body temperature and constricted pupils (miosis).   Coma or death may occur.
  • Stage III : 24-72 hours post ingestion. Signs often associated with renal calcification. Systemic signs such as severe depression, vomiting (can be artificial neon green color), diarrhea, dehydration, increased measured kidney values (BUN and Creatinine), urinating a small amount frequently, or large painful kidneys on abdominal palpation. Animals presented in this stage have very poor prognosis.

Diagnosis

• Your veterinarian may be able to perform a blood test to measure to test for ethylene glycol.   This test needs to be performed within 12 hours of exposure to be accurate. Other medications and treatments (such as propylene glycol) can cause false positives. If the test is not performed early after ethylene glycol ingestion (within 18 hours of ingestion), false negatives can occur due to clearance of the chemical from the body.
• Other laboratory tests including blood work, urinalysis and abdominal ultrasound (classic “halo” sign within the kidneys) may help guide the diagnosis. Take note of the ultrasound image to the right; the arrow is pointing to the "halo" sign.

Treatment

• Known antidotes (4 Methylpyrazole or 4 MP) can be administered to your pet to help prevent damage caused by Ethylene Glycol. This is currently only acceptable in dogs. They may be beneficial from 8-36 hours post ingestion. Antidotal treatments are often continued until the ethylene glycol test is negative.   Side effects include excessive salivation, gagging, increased respiratory rate and trembling. Rarely, liver toxicity has been associated with ethylene glycol ingestion.
• Other treatments include ethanol administration. Side effects can include depression, but is safe in both cats and dogs.
• Aggressive fluid therapy is concurrently administered to flush out the kidneys.
• If your pet is presented within 4 hours of ingestion, induction of vomiting, or gastric lavage (“stomach pump”) under general anesthesia may be performed. Activated charcoal may be administered orally to prevent absorption of the chemical from the gastrointestinal tract. Often this is followed with an enema to enhance elimination of the poison.
• A urinary catheter may be placed to monitor urine production.

Prognosis

• Prognosis directly correlates to the amount ingested and time of treatment administration. Prognosis for any animal exhibiting any of the clinical signs is grave. If exposure was within 1-2 hours, prognosis is guarded.

References

1. Gfeller RW, Messonnier SP. Handbook of Small Animal Toxicology and Poisonings. Philadelphia , Mosby, 1998, pp. 135-139.
2. Osweiler GD. Toxicology. Philadelphia, Williams and Wilkins, 1996, pp.319-320.
3. Plunkett SJ. Emergency Procedures for the Small Animal Veterinarian.   London , Saunders, 2000, 319-326.
4. Murtaugh RJ, Kaplan PM. Veterinary Emergency and Critical Care Medicine. St Louis , Mosby, 1992, pp. 447-448.