Doxycycline...Question

Carl has had one week of Clavamox (which didn't clear up his cold) and so far has had 5 days of Doxycycline which has worked wonders.

He only gets 1/4 of a pill once a day b/c it upsets his stomache otherwise. He seems to be getting better quickly, and now only has a barely recognisable snort and the occasional snotty sneeze. He has 10 days worth of meds that the adoption vet gave me to give to him.

My question (and I will contact the rescue vet, but it's hard to get in touch with her understandably, so I turn to the TCS experts): Is Doxycycline like an antibiotic that you have to finish the full treatment for it to take affect? If Carl is feeling better, can I stop the meds?

With all antibiotics it is always best to finish the full run unless the vet has specifically stated not to.

A little yogurt mixed in canned food daily should help with the stomach upset.
Or ask the vet for a probiotic (just remember to give probiotics well apart from antibiotics as they can negate each other).

Doxycycline was one of three antibiotics that I have been on for my bite abscesses. I took it for two weeks and the doc (I nearly said vet!) told me to finish the full course. I would say it is the same for cats.