My dog (6 month-old lab) is like yours in that he will want to say hello to everyone and everything. I always put him back on the lead whenever there's any other dog nearby just in case one is nasty.
Hope yours is on the mend OK.
Current: 2014 F31 320d M-Sport, Professional Media, Visibility Pack, Reversing Camera, DAB
Previous: 2013 F10 520d M-Sport, 2011 F10 520d M-Sport, 2008 320i M-Sport Coupe, 2002 325i, 2001 318i valvetronic, 1998 318i, 1996 525i, 1990 Porsche 944S2