I'm in the UK too, if that makes a difference to any recommendations.

My three cats had similar problems.  Thanks to people in this
group, I started feeding them Royal Canin, Indoor Formula 27.
Within less than two weeks, the dandruff flakes disappeared,
their coats became bright, and they rarely vomit now.  Obviously,
the Iams I was feeding them was really the garbage that people
here were saying.  Oh, I fed them Science Diet and had the
same problems.   The Royal Canin is just a tad expensive but
nothing but the best for the fur babies.

Experiment with different foods and feeding regimens until you find
what *your* cats thrive on and don't have bad breath.  Mine thrive on
food that costs less than the major brands I used to feed (good thing
too, since I had four then and fifteen now).

You might want to go to the local feed 'n' seed/pet shop and ask about
coat conditioners. You massage this into their scalp (for lack of a
better word) and it might relieve the flaking. Kind of like hair
conditioner is for human servants.

My vet's office said dry flakes are usually a lack of Omega 3. I know
someone on a newsgroup from a pet food company said it's a tough balance
with cat food because Omega 3 is a fat, and extra fat in the food can
add extra fat onto the cat. He said it's tough because owners want their
cats' coats to be pretty, but they don't want to add all of the extra
calories.

Rhonda

my vet gave me a pump bottle of oil to remedy that.

I used it for a year and got fed up!
I now feed them the best food (Innova Dry and Natural Balance canned and
sometimes Innova Evo canned)
No more problems.
I appreciate it can be more expensive, but I expect better fur and a longer
life - Iams and other carp foods are just a slow death!

Much depends on the quality of the tinned food you are using.  I am not
familiar with which products are available in the UK.  However, I live in
the US and use premium-quality canned food -- primarily Wellness canned
(several varieties) and Innova Evo.  Your cats will be healthier if you use
canned food exclusively and either eliminate dry food or give small amounts
occasionally as a "treat."  I feed canned food on a 12-hour schedule, or as
close to that as possible.  I used to feed dry food, and Holly always looked
and acted healthy but had a considerable amount of dandruff (which shows up
easily on her black fur).  Once I changed to the curent diet, her dandruff
disappeared and her fur took on an even richer, more glossy sheen.  So, my
recommendations would be to (1) eliminate dry food and (2) make sure you use
premium-quality canned food.  I even found that the change in diet did not
cost much more because this food is so "dense" that each cat only needs 1/3
of a 5.5 oz. can twice a day.

MaryL