aggression towards animals on our property

Question
we have a 2 1/2 year old male chihuahua and he is sowing agression towards his 4mth old son and a new 8wk old bitch.
he's fine with our other female who has been with him for a while, but not so friendly with our cats who have been with us longer then him. also agressive towadrs us occasionally

Answer
That's a lot of aggression from a little guy! Your child, your new puppy, your cats and you...without more specific information, it would be hard to ascertain the triggers/cues that lead up to aggression and how is that defined? What does he do when he is aggressive? Has he actually bitten someone? Or is it a bunch of noise?

Since you have a 4 month old child, I strongly suggest that you have someone come out to evaluate and get this under control, before your son is toddling. Try www.ccpdt.com