Many antifreezes are toxic to animals, and just an eighth of a teaspoonful can be enough to kill an animal and cause a very painful death.
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I lost my 2 and a half year old cat who had ingested antifreeze. This could have been as simple as someone spilling some and the rain creating a puddle and her drinking from that puddle.
The next morning she had lost the use of her back legs, dragging them and couldn't hold herself up She had acute kidney failure and the kindest thing to do was to put her to sleep.
Animals need immediate treatment to survive poisoning by toxic antifreeze, and this is often not possible.