My 9 yr old(recently rescued)female is not a boxer but a springer whose colitis has not responded to metronidazole--vet put her on Batril as he is hoping she will have the boxer form of colitis and respond to it.

I'm not familiar with a "boxer" colitis. Not to say that it doesn't exist.
For example German Shepherds can suffer from a stomach ailment that results in diarrhea and weight loss that requires specific testing. I would have to search for the name as it is not something that we encounter on a regular basis.
Anyway, did your vet rule out internal parasites?
Is the stool gooey, slimy or loose and watery? Do you see blood in the stool ever?
Also have you recently rescued her or have you had her for a while now?
If she is having stomach issues a bland diet would be helpful, did your vet suggest any special diet for her?

Boxer colitis exists... The only true way to cure it is to have a colonoscopy and sample the tissues of the GI tract for an over growth in E.coli. However, that pricey procedure doesn't always agree with people's wallets so vets will often prescribe baytril for long term use.

Follow your vets directions. If you stop and start, the E. coli in the GIT becomes resistant and it'll be an expensive fix.

Interesting Lucky, I was looking for some info on it.

And I found this
http://www.ncbi.nlm.nih.gov/pubmed/19678891

I have never heard it called Boxer Colitis, so I've actually learned something here today.

Springergal, the treatment referred to in this study is enrofloxacin, which is just another name for Baytril, so it sounds as if your Vet has you on the right track.
I'd stick with his/her plan and see what happens.
Good Luck

I think the technical term is "Granulomous Colitis" or something along those terms.

Kind of funny, I happened to have just read an article on it a few hours before I posted on here..

Its called boxer colitis because it's most commonly found in Boxers and they are prone to it. But like with any disease, it can appear in other breeds as well. Just not as frequently.