Reminds me of the bond my Vegas had with the neighbors lab. Bailey would come over every morning and "knock" on the back door for Vegas to come out...they would kiss each other and hang out for a bit, sometimes play. When Vegas broke his leg, Bailey was out of his mind when he didn't see him each morning...I ended up having to let him in the house (which really pissed the cat off) and allow him to give Vegas a kiss or he would be howling at the back door all day.
Bailey passed away a few years ago of old age, Vegas was only a few years younger and he still goes over to the neighbors hopin he will show up...