violent 5 yr old nephew

[angryaunt224]

My nephew is 5 yrs old ( just a few days younger than my own son), he has violent fits, breaks everything, and seems to have no ability to cope or understand rules. If you try to explain to him why he can't or shouldn't do something he cusses at you, if you put him in time out he urinated on his toys or rips all of his clothes out of his drawers. He throws sharp objects at people, jumps off everything with out thinking of his own safety or others. He has shown my s ok n his penis and tried to get my son to show him his ( he refused) . He has always acted this way, he seems to have no pain limits. Most recently I witnessed him hanging his mom's Pomeranian off a truck bed by her leash, laughing that it was choking and struggling.
I do not allow my son to play with my nephew anymore unless myself or my husband are present. I am, in turn, receiving a lot of flack from my in-laws about "boys will be boys, and he will grow out of it". I think there may be something else going on, should I be worried? Am I being over-protective of my own son? Or over-reacting to what I consider violent and unacceptable behaviour?

[Sandman2]

   Agree completely with Mark.

[MarkLakewood3367]

The behaviors that you described sound very excessive, clearly not age appropriate.  The first thing that I would do is have your nephew evaluated by his pediatrician to rule out any medical issues that might be triggering this behavior.  You might also want to ask the pediatrician for a referral for a mental health evaluation to rule out emotional and psychological reasons that might be triggering this behavior.  But if you ask me if I think you should be concerned about his behavior, the answer is unequivocally yes.