Antifreeze is extremely toxic to cats. Ingesting small amounts, like a teaspoon, can lead to severe kidney damage and death. If you think your cat has ingested antifreeze, take them to see a vet immediately.   

The antifreeze toxin is called ethylene glycol. It is most often used in radiator fluid, but may also be present in some windshield de-icing products, motor oil, brake fluid, paints or solvents. Unfortunately, it has a somewhat pleasant taste, so many cats will drink it if they find it. Initially, it causes symptoms similar to being drunk (alcohol poisoning). If the cat recovers from these initial symptoms, they often develop signs of severe kidney disease within 24 hours. Immediate intensive care is needed to prevent this from happening or support recovery if possible.

What is antifreeze toxicity in cats? 

The antifreeze toxin is called ethylene glycol. The lethal dose of ethylene glycol in cats can be as low as 1.4 ml/kg. The product is quickly absorbed from the stomach and spreads throughout the body. The intoxication develops in three stages:

• In the first 30 minutes to 12 hours, the symptoms are mostly related to gut irritation and brain disruption. Severe cases may develop seizures.

• After 12 hours, the visible signs may appear to improve. However, the body’s attempt to get rid of the toxin actually causes more damage. Dehydration develops or worsens, and we may start to see changes to the heart rhythm and breathing.

• Within 24 hours, symptoms of kidney failure develop, as well as worsening of the previous symptoms. Urine production slows down or stops. Severe lethargy may turn into coma, and cats may pass away even with intensive treatment.

Symptoms of antifreeze toxicity in cats

First stage (30 min-12 hours):

• Drooling

• Vomiting

• Confusion or sedation

• Wobbly movement (ataxia)

• Excessive drinking

• Excessive peeing

• Seizures

Second stage (12-24 hours)

• Dry, sticky gums

• Loss of skin elasticity

• Eyes lose their shine and may appear sunken 

• The heart beats faster

• Breathing may become faster and shallower

Third stage (12-24 hours):

• Complete lack of appetite

• Very low energy or sedation

• Drooling

• Bad breath that smells of ammonia

• Vomiting worsens again

• Mouth sores may develop

• Peeing reduces or stops completely

• The kidney area (below the loin) becomes painful

• Fast heart rate and breathing

• Dehydration

• Seizures

• Coma and death

Cats at a higher risk for antifreeze toxicity

• Sadly antifreeze poisoning can affect any cat

• Cats that roam are more likely to be exposed to antifreeze

• It is more common in young cats, probably due to them exploring their surroundings more

• Cats that already have kidney problems are likely to be more severely affected

Diagnosis of antifreeze toxicity in cats

• Blood tests are available to detect ethylene glycol, but these only work during the first 24 hours after ingestion.

• General blood and urine tests may provide some clues.

• Later in the disease process, further changes can point to the diagnosis, such as the sudden formation of large amounts of calcium oxalate crystals in the urine. These changes indicate a case being more severe.

• If there is any suspicion of antifreeze poisoning, it’s usually advisable to start treatment immediately and not wait for confirmation. This is because of the severity of the condition and how quickly it progresses.

Veterinary treatment of antifreeze toxicity in cats

• The first and most important step in treating intoxications is to stop the poison from getting into the blood and organs. If antifreeze ingestion is suspected, the stomach should be emptied as quickly as possible, ideally within 30 minutes. Your vet will do this via an injection or by pumping the stomach under anaesthesia. 

• Most cases will require hospitalisation for close monitoring and treatment of symptoms. Hydration is carefully maintained to protect kidney function.

• An antidote exists for antifreeze poisoning (fomepizole), but it may be difficult to access. Ethanol (drinking alcohol) can be used as an antidote if given as a medication, but it carries a high risk of serious side effects. 

• Intensive hospital care is usually needed for 1-3 days, more if kidney damage develops. 

Home treatment of antifreeze toxicity in cats

Always contact a vet for advice immediately if you think your cat has ingested antifreeze. Immediate emergency care is essential. 

Prevention of antifreeze toxicity in cats

• Antifreeze and any other products containing ethylene glycol should be carefully stored in secure, locked cabinets.

• Radiator fluid leaks should be immediately and thoroughly cleaned up.

• Cats should not be allowed to roam around garages or vehicles that are not properly maintained.

Living with antifreeze toxicity in cats

If absorption of the poison can be prevented and supportive care is provided, cats may not suffer any ill effects. Unfortunately, this is very difficult to achieve, given how quickly the toxin is absorbed. If kidney damage develops, cats may be left with long-term complications even if they survive.    

When to worry about antifreeze toxicity in cats

Always speak to a vet immediately if you suspect your cat has ingested antifreeze, so the risk can be assessed and treatment advice given. 

If your cat develops any of the following symptoms, see a vet as soon as possible:

• Severe vomiting or drooling

• Confusion or wobbliness

• Weakness or collapse

• Trouble breathing

• Seizures

• Excessive drinking and urination