How scary would it be to discover your dog vomiting green stuff? Quite scary even though it typically doesn’t involve demons or extraterrestrial lifeforms.
Now, bile/stomach juices can have a greenish tint to it. In theory anyway; I’ve never seen bile vomit of that color. I’ve seen various shades of yellow and white, but not green.
After eating enough grass, vomit can look green but that is not the color I’m trying to depict above either. What we’re talking about here is a very green color. Really, really green.
Bright green vomit is an emergency.
Edible things don’t come in technicolor. I still remember the case of my friend’s dog who managed to eat about 130 paintballs. I guess it seemed like a good idea at the time. This feast ended up with severe sorbitol toxicity. With aggressive treatment, the dog made it through the ordeal. If want to see what the technicolor vomit looked like, you can see it here.
Paintballs do not qualify as a healthy snack. Paintball toxicity generally ranges from moderate to severe. It’s not very common but neither is green vomit. The paintballs my friend was using were supposed to be non-toxic. Supposed to be being the keyword.
That dye is a favor to dog parents, since then you at least clearly see there is a problem. Unfortunately, not all rodenticides come with this feature, and some of the newer types don’t even come with an antidote. That is a material for its own post, though.
Vomit that has the fluorescent green color of antifreeze can indeed mean antifreeze poisoning. While dogs find antifreeze appealing for its sweet taste, it is extremely toxic.