totally confused - question on overweight kidney problems and diet!

Hi. My 15 yr old cat was taken to the vet with a problem on foot and
had toe removed due to a oesteosarcoma. Whilst being treated he was
also found to have early stage heart and kidney disease and is now on
Fortecol tablets. I have been advised by the vet to get him onto Hill
t/d or k/d food. He is significantly overweight due to being inactive
and I also need to get him to lose weight.
Both my cats (both 15 and my other cat v. slim) have been fed 'wet
food' as I believed it better, half a sachet/tray each twice a day. My
problems are in the transaction between this to dry food.

Question 1: any idea how much dried prescription food I should be
giving my overweight cat - is it 50%/70%/??% of usual recommendations?

Question 2: Other cat has now got diarrhoea from the change of food -
should I persist or put him back on wet food? He's starting refusing
food and drinking a lot of water.

Question 1: any idea how much dried prescription food I should be
giving my overweight cat - is it 50%/70%/??% of usual recommendations?

I am not a vet but I would advise against feeding the prescription
food, especially dry. Cats with kidney problems will need the water
the wet food provides. Have you looked at the ingredient list of this
food? They are usually filled with stuff you can't even pronounce! I
have taken vet's advice about feeding prescription diet food and
nothing worked (and my cat was constantly hungry!) So I switched him
to a grain-free, all canned diet and the weight slowly came off. The
formula I use is:
For normal weight cats: 15 calories/per pound of body weight/per day
For overweight cats: 10 calories/per pound of body weight/per day

I used grain-free Wellness but there are other brands similar to this.
Wellness has approximately 32 calories per ounce. Weigh your cat
weekly and slowly cut back on the amount of food he gets. I saw slowly
because you don't want him to lose weight too quickly! I have a web
site about weight loss he http://community-2.webtv.net/getcathelp/tucker/

Question 2: Other cat has now got diarrhoea from the change of food -
should I persist or put him back on wet food? He's starting refusing
food and drinking a lot of water.

I would keep this cat on wet food. If it was working for him before,
why do you need to switch? If he's overweight too, you can use the
same formula as I wrote above. If you were switching him to dry,
that's why he was drinking more water. He probably didn't drink much
water before as he got the water from the wet food.

Here's another article you should read. Feel free to email me with any
questions. http://www.catinfo.org/

Firstly switching a cat with renal issues to dry food is insane. You
should be adding fluids to your cat's food, not taking it away...
Hydration is the key treatment. Also, diarrhea further dehydrates your
cat, making the sick kidneys work even harder. Stop feeding that
expensive crap and return to what worked.

Please change vets, asap. This one will not be of help to you. Keep
in mind that if you are lucky your cat will live with the kidney
insufficiency for many years (mine lived 8 years). You need a partner
in your vet not someone who will undermine your efforts.

Also, the so called renal diet for cats is a total failure. It at
best does nothing and at worst can cause many other health issues.

There is a very good, very active forum on yahoo groups called Feline-
CRF-Support - sign up. Also two websites that will be of help:
http://www.felinecrf.org/ - you'll find all the info on CRI (chronic
renal insufficiency) here and http://www.catnutrition.org/information_resources.php
- you'll find all the necessary resources on feline nutrition.

Good luck.