Try different brands: Purina (US) brands generally cause bad breath,
but the Walmart house brands and some of the major brands don't. When
making any change in the feed, be sure to keep a close eye on the
cat's health, weight, and coat.  On the Walmart brands (and the
significant supplement of what they catch), my cats have better coats
and are mostly a little heavier (for some, heavier is good, for one,
its bad).

--
T.E.D. (tdavis@gearbox.maem.umr.edu)

Most cats develope bad breath at some time usually due to a build up of
tartar on their teeth, you could try your kitten on Royal Cannine Tartar
control dried food, all but one of my five cats love it.