As a smart collection, I think this is it:
Keywords / Contains / Dog
(Now use the Alt/Option and click Plus)
None of the following are True
- Keywords / Contains / Prairie
Keywords / Contains / Violet
Rory, my understanding is that the smart collection interprets two or more words not as a phrase but as two separate words. So your bullet points read "Find images with dog in the keywords but without 'prairie' in the keywords and without 'dog' in the keywords...."
Yes, there should be a way to say Keywords/ Exactly Equal/Dog. Lots of other stupidity there too - ever tried making a smart collection to find those with empty titles or captions?
John