The parent commenter has probably, like me, heard that pigs are remarkably intelligent. I haven't heard the same of cows.

That may very well be a skewed understanding, but it's likely why they choose that grouping.

Personally, I don’t see cows as very different from dogs.

They’re just as social and emotional as dogs are.

Intelligence wise, dogs are probably a bit smarter. But how much, I don’t know, they don’t seem that radically different.

I suspect you have more experience than I, and I know my imagining is poorly founded!

I think pigs have just received enough good PR recently that they come to mind as another particularly intelligent animal.

Maybe the size also helps? Closer to a dog or a cat, cows are not.