Two cats from the same Leighton Buzzard street were poisoned within days of each other, prompting an appeal from the RSPCA.
The animal charity says it is unclear at this stage if the deaths were deliberate or accidental, but is keen to hear from residents who may know more.
A five year-old cat called Sasha and 15-year-old Tilly died within two days of each other in the middle of May.
Heath & Reach Veterinary Surgery saw both the cats and say their symptoms were consistent with anti-freeze poisoning.
RSPCA inspector Jamie Godfrey: “We are extremely sorry to hear about the deaths of these cats, it was devastating for the owners.
“It is difficult to know if this is an accidental incident or deliberate but in the meantime we would ask for everyone in the area to check where they keep their anti-freeze and make sure it is secure and out of the way of cats.
“People should check their cars for any leaks too.
“It is possible that people were simply unaware of the potential hazards to cats when they poured the antifreeze away.
“Similarly we cannot rule out that this was a deliberate act of cruelty and would ask anyone who has information to this effect to contact us immediately.”
Signs of antifreeze poisoning can be seen anything from 30 minutes after a cat has ingested the chemical, though it can be two or three days before signs of kidney failure are seen.
The signs of poisoning can include one, or several of the following vomiting, seeming depressed or sleepy, appearing drunk and uncoordinated, seizures, diffculty breathing, increased thirst, increased urination.
If you suspect that your cat has been poisoned take it to a vet immediately. If possible, you should take a sample of what the cat has eaten/drunk, or the container.
Poisoning a cat deliberately is a criminal offence. Under the Animal Welfare Act 2006, the maximum penalty for those found guilty of this offence is up to six months imprisonment and/or a fine of up to £20,000.
If anyone has any information about suspected anti-freeze poisonings they can contact the RSPCA inspector appeal line in confidence on 0300 123 8018.