My elderly mother had a fall.She's in a rehab facility and I have her cat

Mom lived alone in a one story condo.

My daughter and I got her this cat (Brie) from a shelter after her previous cat of 16 years died. She's had Brie for about 2 months. Her vet thinks Brie is a little younger than a year.

Well, Mom fell, sustained a pelvic fracture and will be in rehab for a least the next six to eight weeks.

I'm the only kid in town, and so we took Brie, since we live quite a distance from Mom's place and decided the cat shouldn't be alone.

We have a Golden Retriever and a cat who's about 15 years old. The dog is completely neutral and doesn't hassle the cat, however, Brie is hissing at Bonita (our old girl) and challenging her, even though Bonita is not agressive. However, Bonita has finally had enough and swatted Brie and it's not going well.

Any suggestions? MKJ

edited to add: Please?

Some advice about introducing cats in this thread:

http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=243x13709

It will most likely take a little while, and the thread pointed to in the last reply has good advice.

Cats don't make friends as quickly as dogs do.

be "best friends", but they will work out the worst of their issues.