Antifreeze Poisoning In Pets – Symptoms & Prevention

Antifreeze - The Fatal Toxin

Antifreeze contains 95% ethylene glycol, a deadly substance for animals. It is sweet, tasty, and seen as a source of energy to our pets. Given a chance, they will consume it in large quantities. Without rapid veterinary treatment, this toxin will be fatal. 

With winter around the corner, we need to be especially wary as the use of antifreeze is more prevalent, particularly in urban areas where there is a higher volume of vehicles. It can leach from cars into puddles.

Other products also contain this deadly substance such as some wood varnishes, ink cartridges, paint, and tile adhesive albeit in much lower percentages but should never be ignored if ingested or contacted topically. 

Ingesting as little as a ¼ of a teaspoon per kg of body weight can cause toxic signs. Although it is not well absorbed through the skin, topical contact causing fatality has been reported in cats. 

Top tip: if your pet does get something concerning on their coat, wash thoroughly with washing-up liquid prior to heading to the vet. This form of decontamination can increase their survival rate.

The minimal lethal amount is approximately 4-7mls per kg of body weight for dogs and just 1.4mls per kg for cats, therefore it really doesn’t take a lot to cause death. It is rapidly absorbed post ingestion and distributed around the body. Clinical signs can be seen within minutes; however, it can be delayed if your pet has recently eaten as food slows the absorption. 

Symptoms change and worsen over a 3-day period, left untreated your pet will die. Most animals will not survive past 24 hours, especially cats. Sometimes they can appear to look better, but do not be fooled by any improvement, the kidneys will fail to head for an extremely poor prognosis.

What are the signs?

• Vomiting, maybe profuse
• Anorexia (not wanting to eat)
• Salivating
• Ulcers maybe seen inside the mouth
• Looking drunk when walking, known as ataxia
• Depressed
• Polydipsia which is an increased thirst
• Hypothermic so body temperature drops below 37.5°C (normal temperature for dogs and cats is 37.5-39.2°C)
• A fast heart rate known as tachycardia
• Rapid abnormal breathing rate known as tachypnoea 
• Early on you may see an increased urine production but within hours this will lead to decreased urine production then a complete lack
• Abdominal pain
• Seizures and tremors
• Coma

This toxin affects the animal’s neurologic, digestive, urinary, and cardiac systems, making it so deadly.

What is the treatment?

Your vet may make your pet sick (known as emesis) if seen post-ingestion rapidly, however, this is very risky as the animal can inhale the vomitus known as aspiration. This will complicate things for this toxin further. Emesis is a common approach for many other toxins, however. Never be tempted to make your pet sick at home.

Charcoal is commonly used to ‘’mop up’’ any remaining toxin and is commonly given orally to many pets after emesis, however it is not useful for ethylene glycol cases. 

Fomepizole is the antidote of choice but isn’t always readily available. For a good prognosis, it needs to be administered by your vet within 5 hours ideally but a maximum of 12 hours for dogs with the prognosis becoming poorer with time. For cats it needs to be given within 3 hours, otherwise the toxin is very likely to cause fatality. Of course, you may not even be aware your pet has ingested it, especially with cats who go outside. 

An alternative to Fomepizole is the use of intravenous vodka or potentially another clear alcohol. It can be administered to both cats and dogs to block the effects of ethylene glycol, and if given early on can be a lifesaver. Your vet will also monitor and manage your pet’s glucose levels, use gastric protectants, administer oxygen, and possibly pain relief.

Treatment is intense and your pet will be required to remain in hospital for a few days.

How can you minimise exposure?

This is easier for dogs compared with cats who independently go outside. Prevent your dog from sniffing around garages, cars, and driveways especially if you see any suspicious drips of fluid. Mop up any spillages and regularly check your car radiator for leaks. Keep bottles out of reach and tightly sealed.

Use propylene glycol-based antifreeze products instead. It is much less toxic to your pet, and less desirable to them. This would be a much safer alternative. If we all switched to this, we would see far fewer intoxications.