I know I'm late reading this, but have you taken Kirri to a vet and had a general checkup, in addition to getting the bites fixed?
It sounds like the dogs have gotten along really well for quite a while, so something changed to set this off. You said Kirri is quite old so the first thing I can think of that might have triggered this is a change in health. Something that maybe changed Kirri's smell, or how she moves, something subtle that Jada is picking up on.
Dr. Seuss~DLH (brother's cat)~June 2007-
Misty~DSH (my cat & Mooby's mom)-?-
MooBoots(Mooby) ~ DMH(Mom's cat)~July 21, 2008-
Sunshine~ Golden retriever X white german sheperd (Dad's dog)~October 24, 2008-