Have you ever looked at the antifreeze in your car? It's usually some florescent color like blue or green. I've heard of some antifreeze being pink. They companies that produce antifreeze actually add the color to it because it is clear without it. They are worried that if the car had a leak, people would not know that it was antifreeze and if a pet slurped it up off of the driveway we would think they were just getting a drink of water.
"Why would a dog drink antifreeze?" you say? The answer it simple.
Antifreeze is sweet.
Weird, huh? Apparently it has a very sweet taste that goes well in wines. Don't actually try it--it's poisonous. The manufacturers add the color to give it the tree frog effect: bright colors mean a tasty but deadly treat.
I mentioned that it goes well in wines. A while ago there was a wine competition (is that what they're called?) in Austria and one wine was spiked with ethylene glycol. The flavor of the wine was so enhanced that they won. Once discovered, that wine company went out of business.