Symptoms and Signs of Antifreeze Poisoning in Dogs

Source: PetWave, Updated on July 16, 2015
Antifreeze Ethylene Glycol

How Antifreeze Poisoning Affects Dogs

Once ethylene glycol (EG) is metabolized into oxalic acid and binds with calcium in the blood, it forms calcium oxalate crystals that are deposited in the kidneys. At this point, the dog will become very, very ill. Its symptoms will include depression, vomiting, convulsions, gastric irritation (upset stomach) and extreme pain. Seizures, coma and death are common. Obviously, these are highly unpleasant and potentially catastrophic consequences for the dog.

Symptoms of Antifreeze Poisoning

Ingestion of antifreeze can cause a myriad of observable symptoms in dogs. The symptoms of antifreeze toxicity typically develop in three separate stages. Stage 1 usually occurs within approximately 1 hour after the dog ingested the antifreeze and can continue for up to roughly 10 hours. If the dog is kept primarily outdoors, the owner may not even notice the signs of Stage 1 antifreeze intoxication. When the owner does observe signs, they typically resemble signs of alcohol intoxication and include one or more of the following:

  • Lack of coordination (ataxia)
  • Depression
  • Lethargy
  • Stupor (“drunken sailor” behavior)
  • Stumbling
  • Excessive thirst/intake of water (polydipsia)
  • Excessive output of urination (polyuria)
  • Gastrointestional irritation and discomfort; nausea
  • Vomiting
  • Low body temperature (pronounced hypothermia)
  • Convulsions/seizures (rare in Stage 1)
  • Coma (rare in Stage 1)
  • Death (rare in Stage 1)

Stage 2 of antifreeze poisoning in dogs usually occurs between 12 and 24 hours after the dog ingested the antifreeze or other substance that contained ethylene glycol. During this stage, the neurological signs of EG toxicity may wax and wane (come and go), and the dog may seem to return “back to normal.” However, unbeknownst to the owner, during Stage 2 the dog may develop:

  • Rapid breathing (tachypnea)
  • Rapid heart rate (tachycardia)
  • Dehydration
  • Progressive weakness

Without treatment, the dog will enter Stage 3 of antifreeze toxicity between 24 and 72 hours after it ingested antifreeze or another substance containing ethylene glycol. The consequences of this stage are due almost entirely to the disastrous effects of the toxic metabolites of ethylene glycol on the dog’s kidneys. By the time it reaches Stage 3 of antifreeze poisoning, the dog will be in acute and probably irreversible kidney failure. The signs of this terminal stage typically include:

  • Depression – severe
  • Lethargy – severe
  • Weakness - severe
  • Painful kidneys (severe abdominal pain)
  • Swollen kidneys
  • Decreased production of urine (oliguria)
  • Absence of production of urine (anuria)
  • Lack of appetite (inappetence; anorexia)
  • Vomiting – profuse and continuous
  • Oral ulceration and pain
  • Excessive salivation (ptyalism)
  • Low body temperature (hypothermia)
  • Low blood pressure (hypotension)
  • Seizures/convulsions
  • Tremors
  • Abnormal eye movements (nystagmus)
  • Collapse
  • Coma
  • Death

Dogs at Increased Risk

Any dogs with access to antifreeze or other substances that contain ethylene glycol have an increased chance of being poisoned by ingesting those substances. Antifreeze is thought to have a mildly sweet flavor that is interesting and tasty to domestic dogs. Dogs that live primarily or exclusively outdoors, and those that are permitted to roam freely about the neighborhood, have an increased risk of coming into contact with antifreeze. This is especially true in cold climates. However, it is becoming increasingly common for people to flush their radiator fluid during the summer and fall months as part of routine car maintenance. This has made antifreeze poisoning a year-round problem in companion animals.

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