If I use the /pets/name url instead of /petinfo.php?petid=petidnum, the profile page defaults to this pet which appears to have the legacy name [void/no char/empty field]
I'm guessing this is related to hidden fields issue.
Please keep us updated if we should no longer use the legacy name url for pet profiles (/pets/petname).
[ edit ]
oh. Did I miss something in the last 3-6 months? is pet/name supposed to no longer work and we're supposed to now use pet/username/petname, and/or [pet not found] ?

Now that we have non-unique names (meaning anyone can have a pet name like Christopher) the links are now through the username like in your edit. However, if you have the original Christopher, you would normally be able to use the /pets/name link. It is currently broken and you can see that report below.
Dexter by ❤