You need to teach a strong "LEAVE IT" and protect the old cat. I've had a lot of different cat/dog issues over the years and some cats like dogs and others do not. Just recently it took me almost 6 months to get my one dog, Kiya to accept the new kitten, she wanted to hurt the kitten. With Kiya the best exercise I did was to have her in a down stay with the best treats I have, homemade liver brownies. Eventually the kitten was able to walk freely without Kiya lunging to kill him. It takes a LOT of work and persistance. Theres not much you can do with the cat, they have a mind set of their own. Has the cat smacked the pup yet?
Apache - Shiloh Shepherd 12/15/02 - 6/9/15
Kiya - Shiloh Shepherd 5/15/04 -12/19/25
Lakota - WGSD 1/13/10
Wolfen - WGSD 12/31/14