“My vet sent home K/D food for my skinny old cat (with chronic kidney disease) to eat. I also have two young cats who find this food delicious and are getting fatter every day! What can I do to prevent the boys from becoming morbidly obese and still have the prescribed food around for Ladybug? I don’t want to keep the old girl locked up.”

Dr. Jess Franklin responds:

Feeding dogs special food is easy because you can separate the dogs, feed everyone twice per day and after 5 minutes pick up the bowls and let everyone out to mix and mingle.

Cats, however, are grazers—they don’t finish all their food in one sitting, usually eating small amounts every few hours.

Here are some helpful hints that have worked for some multi-cat situations.

1. Food out and available must be safe for all the cats. If one has a food allergy, the food this one can tolerate is the only food that can be left out in the shared area.
2. Partial day separation: Every morning, move the old cat with the kidney disorder to a room that has a sleeping perch and litter box, and put out fresh portions of can and dry special renal diets. When you return from work, open the doors and let the cats mix. The young cats will move in and finish her uneaten remnants, but she had hours to graze on the special kidney foods.
3. The skinny feeding shelf: The old cat can be lifted to a high counter and offered food while you pet and stroke her. The attention may encourage her to eat, and you can tell the boys they aren’t welcome on the counter while you are there. If the fat cats are very large and the old cat very thin, a 3-inch space in front of a shelf of books may be wide enough for her to perch comfortably, but too narrow for the larger, wider cats to be able to fit.
4. Use the lowest calorie type of kidney food. In my experience, Hill’s K/D is the best for allowing the very skinny cat in renal failure to gain weight, but other foods like Purina NF and the Royal Canin LP are less prone to making the whole group of health cats gain weight.