How do I train my border terrier?

Question
Hi,
I have had my female border terrier since May. She has been through many things....we got her from the pound so she was spayed, she had kennel cough, and just recovered fromm parvo. Her age is somewhat in question, but our vet thinks she is just about a year or a little less. She is such a sweet dog, but lately she has been growling at my 7 year old niece, and she is starting to growl and lunge at my youngest cat, who is a little over a year old. She was very amiable with everything and everyone, but now it seems like she is getting very possessive of me. I thought maybe it was due to all the time I have spent nursing her back to health through her ordeals. I have 5 cats, so we need to work something out here. How should I handle her when she starts growling? Thanks for any help.
Joan

Answer
Hi Joan,
 Yes it sounds like she is getting a bit possessive.  You need to tell your dog NO.  Perhaps put a chain on her with a leash attatched and correct her for doing that.  Terriers are thick headed and when you correct her it has to be stearn.  You won't hurt her thats for sure.  
 Plus have thought about giving her a job??  Borders love flyball, agility, and earthdog.  They actually want to please and giving them a job will help channel some of that.  Socializing her in different situations will help with this.  Even putting her in an obedience class.  
 Also you have to not treat her like she is sick or had such a hard life anymore.  Treating her with kit gloves will enhance her behavior.  You have to take charge otherwise this little dog will take charge of you.  That wouldn't be pretty.
 Hope this helps.......Please let me know how things go.
Good luck,
Tammy