This was a perhaps slightly oversized paperback book with illustrations of different dog breeds. I believe the cover had a green border. I’ve been been poking around online to see if I could find an old copy with no luck. So far the closest thing I’ve found that’s similar are the illustrations from How Why Wonder Books Dogs Wild Animals Irving Robbin Martin Keen, 1962.
The illustrations were grouped in a certain way on the page, similar to these (but it wasn’t these books):
It’s not impossible that our paperback was a reprint of a 1960s book. There were no photographs in the book, and very little (if any) information about the care of dogs. It wasn’t very wordy. We got it at a garage sale in Michigan in the 1980s.
There’s a 1975 paperback-sized book called The Pocket Encylopedia of Dogs in Color, by Ivan Swedrup, illustrations by Erik O. Stovling, which reminds me of this. Lots of illustrations, no photos, some text but primarily a lot of color illustrations.