Multiple dogs, different ages, different lines, eating two different foods, vomiting today. Multiple others with no issues. Sharing yards, water, inside rooms. Happy, playful, nothing else seems wrong. Initial thoughts?

I have no idea what it might be but I know what I'd start doing. I'd give panacur and Sulfadimethoxine to all of the dogs for possible giardia and or coccidia and give the vomiting dogs peptobismol. It'll probably go away and you'll never know for sure what did it.

Are you sure there is no pesticide, etc., they could have gotten into?

My "initial idea" would be they are all eating poop. That's what's going on here. We shovel it with them locked in the house. They all run out and even if we are out there with a bag and shovel we can't be under 7 different dog fannies at once. The days are short and they are out there pooping after 5PM in the dark--we can't see them eating it then. Suppose I could get a flash light and try--oh these golden years I so looked forward to. Remind me of this when I breed another litter and fall in love with another puppy :(

If they were eating poop I would think they would throw up some of it or at least their puke would smell like it. And yes, I'm out in the dark with a flashlight picking up poop - only 1 may eat it but I would rather she didn't!