Jack Russells with a "temper"

I hope someone on this board can help me...my 2 1/2 yr old male Jack is being very naughty lately! He growls and attacks strange people that come over! I don't know what his problem is. He loves and is exceedingly well behaved when only his family is around but when people pass by the house or come over he wants to rip them apart! Does he need that anti-anxiety medication I keep reading about, or will some disciplilne help? Need advice!

Hi Patti--two questions for you...1st, is he neutered? If not that could be one of the problems. Probably showing his dominant side as well as protecting his family. And question # 2, have you taken him to obedience classes? Maybe he needs more socialization. Only reason I suggested...I teach classes and I do see that it can help some dogs. Good luck to you and your boy Julie, Harmie & Jax (my 2 four-legged kids...pembroke welsh corgis)