more aggresive towards other dogs

by t'ann
(tx)

Hi I have a 1yr old jack Russell and lately when I take her out to walk if she sees another dog she goes crazy, starts making huffing and puffing sounds and runs at them full force. If they are close she acts like she wants to bite or hit at them now I know they are aggressive dogs but it seems she has gotten more aggressive than usual.

Only when she has the leash on, now at the dog park off the leash she is fine with other dogs and plays with them why is that? Also another question, it's me, my hubby and son at home, she plays with them but tends to follow me everywhere does anyone else jr stick to following one person the most?