welsh terrier puppy who is very wild

Question
I have purchased a welsh terrier puppy who is 7 months old.I bought her from someone who owned her for 2 mos and had to give her up due to long working hours. Macee is very sweet, but....she has her own mind. We have a persian cat who is 13 years old, spanky(the cat)is having a hard time putting up with macee. Macee runs after spanky and corners him. Spanky will hiss at her and hit her, but macee does not back off. How can I get macee to leave the cat alone, or how can I train her not to go after spanky?
also... I can't brush or comb macee, she bites the comb or bush and I can't comb her. I think she is afraid of the brush or comb.
How do I stop macee dead in her tracks when she does something she is not allowed to do?
If you can help me correct some of these aggressive puppy problems I will be able to enjoy this cute puppy.
P.S. macee is very smart. She will sit and lay down on command.

Answer
Hello Iris, I have a two suggestions.  While you are with Macee use a shock collar.  The strength on the collar can be adjusted.  What I can tell you is that the shock collar works great and fast and in no time you will not need it.  The way it works is, when Macee has the collar on and you need her to stop doing whatever she is doing give her a voice command and then give her a shock.  When she stops the bad behavior using again your voice praise her.  Repeat as necessary, she will relate the shock with the no command and the no shock with the praise when she stops what she is doing.  The idea is so that when you give her the no command she will stop before she believes the shock is coming.  Eventually your voice will be enough.  You can get this collar at most pet stores or on line at www.petedge.com

Another suggestion would be to go to this website
http://www.dogchannel.com/dog/experts/cesar/default.aspx?Google_Cesar

This man is a wonderful trainer and you should catch his tv show any time you can he has great advice and results.  

Good luck and hang in there if Macee is smart she will catch on quick and you will have the wonderful dog you want.Thanks, Cindy lou :)