Doggyhut Pet Trailer
This is a push cart made for dogs, 'Doggyhut' Model 7030201. You can read more details on the Amazon website, listed for $135 or so. We used it for our Lab that was short one leg the last 9 months of her life, she LOVED it.
We pushed it, but you can also hook it to a bike. It's listed for up to a 90 lb dog. The dog doesn't have to be disabled to use this, they will love to sniff as you take them along.
We are 40 min SE of Milwaukee. I travel around a bit, including towards Chicago. I'll do what I can to help with delivery. The price is $75, pretty much clean as new, no adverse issues.
Sorry, my pictures aren't working out at the moment. This one is blue.