Aggressive Behavior in Dog

Question
Hi Charlotte-  I have a male shar pei mix that is almost 2 years old.  He has always been a very laid back and friendly dog, however, in the past 2 months he has started growling and snarling.  He hasn't bit yet, and all of his aggression is shown to our family.  The hair on his back stands up and he sometimes barks and charges.  Sometimes it's unprovoked and other times if he doesn't want to do what we want him to he gets irritated.  

Some background-  I have 2 kids age 9 & 11 who love him and don't tease or hit him.  Neither do I or my husband.  Sometimes when one of the kids walk into the room he growls.    Also, I have a female doby pup who plays and pounces on him roughly and often.  She is just 6 months old.

We had Harley neutered last week, hoping this would curb the aggression.  Please advise or e mail with more questions.

Answer
Hi Kendall;
I don't know the shar Pei breed that well, so I am not familiar with their traits, so I will just answer about dogs in general.
The first possibility that pops to mind, is, since nobody teases this pup, and it is just family members, he is establishing himself as the alpha dog in the pack.If he gets away with it with fmily, he will soon atart to rule all who walk in his presence.
Dogs are pack animals(as are humans) and there is an alpha (head dog) in the pack (family)
After you have had him seen by his vet, to make sure there is not a physical problem or discomfort ( he could be trying to attract help for a problem)get the lil critter into an obedience class, if he has not already had basic obedience training.
You mentioned the puppy, could he be a litle jelous?
Did this behavior exist before you got the puppy, or did it start aftet this new one came on the scene?
If it started after you got the puppy, he could be jealous, or he could figure, "There are going to be more, so I am going to be the Alpha"
He could be jealous of the family and the puppy, not because he doesn't like the puppy, but because he wants it all to himself.We had a year old male Australian shepherd, and my son brought us a Lhasa puppy. Rowdy (the shep) took over that puppy, and acted like he was it's mother.If it acted up, and I fussed at it, Rowdy would distract me so I wouldn't fuss at his baby.He didn't want anyone to even tell his precious "No" He spoiled that litle runt so we could hardly stand to live with him.LOL
They are 5 and 6 now, and Rowdy still treats Max like he is the father, and Max is the baby son.If he is trying to take over the alpha spot, you have to make sure he knows YOU are the alpha.
Obedience training will do that.
If you don't know how to do obedience training, check with Petsmart and Peto stores. They have weekend classes, that teach you along with the dog.
This is the best way, rather than a trainer taking the dog and training it.
A qualified trainer shows YOU how to train the dog, to give the proper commands etc. The family can go and watch, so they also know how to control this little dictator.
I have re-trained a number of dogs who ruled the family, and made nice, well behaved family members out of them.
The neutering is good, as this is also much better for his health.
Neutering protects males against Prostrate cancer, and helps prevent some other cancers and illnesses.
As soon as the puppy is old enough, ( I like 5 to 6 momths), I urge you to have the puppy spayed. It is not true that is is better for their health to let them have one season, or to let them have one litter.
Spaying before the first season can prevent breast cancer. Yep, dogs can have all those things too.
Charlotte