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Antifreeze Poisoning in Pets: A Deadly Winter Danger in the UK

Antifreeze poisoning is one of the most deadly and preventable causes of death in UK cats and dogs each winter. The sweet taste of ethylene glycol (the active ingredient in most antifreeze) attracts animals, and even small quantities can be fatal. Speed of treatment is critical.

Why Antifreeze Is So Dangerous

Ethylene glycol, the main component of most automotive antifreeze and screen wash products, is metabolised in the body to toxic compounds including oxalic acid, which crystallises in the kidneys and causes acute, severe kidney failure.

The lethal dose is extremely small: for an average cat (4kg), as little as 1.5ml of pure ethylene glycol can be fatal. For a small dog (10kg), around 4.4ml/kg is toxic — meaning less than a tablespoon could kill a small dog. For larger dogs, relatively more is needed, but the toxin remains highly dangerous.

Antifreeze is particularly hazardous in autumn and winter when vehicles are winterised and antifreeze products are left in garages, drip from radiators, or are used to defrost cars. The sweet taste means animals actively seek it out rather than simply stumbling upon it.

Signs of Antifreeze Poisoning

Antifreeze poisoning has a characteristic triphasic progression. In the first 30 minutes to 12 hours after ingestion, the animal appears drunk: unsteady, disoriented, vomiting and excessively thirsty. Some owners mistake this for alcohol exposure or general illness and miss the critical treatment window.

In the second phase (12–24 hours in dogs; 30 minutes to 12 hours in cats — cats progress faster), the animal may appear to improve, creating a false reassurance. This is actually the most dangerous phase as tissue damage is occurring.

In the third phase (36–72 hours in dogs; 12–24 hours in cats), severe kidney failure becomes apparent: the animal stops eating, is lethargic, vomits repeatedly, stops urinating and becomes critically unwell. By this stage, the kidneys are severely damaged and prognosis is very poor without intensive care.

The key message: do not wait for phase three. Any animal suspected of antifreeze ingestion needs emergency treatment within the first few hours.

Treatment: Speed Is Everything

The antidote to ethylene glycol poisoning in dogs is fomepizole (4-MP), which competitively inhibits the enzyme that metabolises ethylene glycol into its toxic metabolites. It must be given early — ideally within 3–5 hours of ingestion — to be effective.

For cats, fomepizole is less effective. Ethanol has historically been used as an alternative antidote, but treatment options for cats are more limited and the prognosis for cats with antifreeze poisoning is significantly worse than for dogs.

Supportive care includes intravenous fluids to support kidney function, anti-vomiting medication and monitoring of kidney markers. In some cases, peritoneal dialysis or haemodialysis may be attempted at referral centres for severe cases. Treatment costs can be substantial — running to several thousand pounds for intensive care management.

Prevention: Practical Steps for UK Pet Owners

Store antifreeze and screen wash products in sealed containers in locked cupboards inaccessible to pets. Wipe up any drips or spills immediately. Be particularly vigilant in garages, driveways and car parks where vehicles may have dripped coolant.

Consider switching to pet-safe antifreeze products. Propylene glycol-based antifreeze is available in the UK and is significantly less toxic than ethylene glycol — though still not safe, so the principle of preventing access still applies.

Be alert to antifreeze risks when walking dogs in car parks and near roads where vehicles are parked — puddles of coloured liquid should be avoided and the area around your vehicle checked before allowing your dog to roam.

What to Do If You Suspect Antifreeze Ingestion

Do not wait for symptoms to develop. If you see your cat or dog around antifreeze or screen wash, or find them appearing disoriented or drunk shortly after access to a car or garage, contact an emergency vet immediately. This is one of the few toxicological situations where 'might have' is enough to justify emergency attendance.

Tell the vet the exact product if known, when ingestion may have occurred, and how much may have been consumed. Take the product container with you if possible — the ethylene glycol concentration varies between products.

The Animal Poison Line (01202 509000) operates 24 hours and can provide specific triage advice. However, given the narrow treatment window for antifreeze poisoning, going directly to an emergency vet while calling from the car is usually the right approach.

Find a Vet Near You

Antifreeze poisoning is a life-threatening emergency requiring immediate care. Know your nearest emergency vet before winter arrives. Use CompareMyVet at app.comparemyvet.uk to find emergency and out-of-hours vet services near you.