You should get wet food, I would imagine any dry food would be difficult for the cat to chew with missing teeth and could damage the cats gums. Talk to a vet

Thank you for your inquiry. Hill's Science Diet Indoor Adult 11+ dry cat food is specially formulated to fuel the energy needs of cats with an indoor lifestyle as they age gracefully. This formula will contain more fiber than our Hill's Science Diet 11+ Adult Chicken Recipe cat food to help with easy litter box clean up. We hope this is helpful. Hill's Pet Nutrition

I’ve been feeding Hill's Science Diet Adult 11+ Chicken Recipe Dry Cat Food to my 19-year-old cat for several years, and he seems to like it.  My 11-year-old also eats it.  I recommend it for older cats.

Thank you for your question. In the early stages of life, young pets need high levels of vitamins, minerals, and other nutrients to ensure proper growth. A food that contains reduced levels of nutrients for older cats may be inadequate for a cat that is in their adult life stage. We hope this helps. Hill’s Pet Nutrition

We would recommend feeding them the Science Diet® Senior 11+ Indoor Age Defying Cat Food Dry as it has a crude fiber content of 8.5 % on a dry matter basis. It contains the same natural fiber blend as the food they are currently on, to continue to assist with hairballs. Thank you for reaching out to us!

This pet food is not intended to promote weight loss.

For the age group of cats that you have I would try the Hills Science Diet Age Defying food. My 16yr. old cat likes it and I like the size of the morsels she can chew them better and therefore less or no throw up. I think it would work for all your 3 cats. Also our cat acts more alert since feeding her this food.

He'll be fine but don't let him do it repeatedly.

The main differences are the decreased protein and increased fiber. Felines are considered obligate carnivores, unlike some other species of animals that are omnivores such as dogs or humans. Protein is metabolized by the kidneys. Thus, a strict carnivore's kidneys work harder than an omnivore's or a herbivore's. The protein values are less in the active longevity formula (for 7+ years of age) than in the optimal formula (under 7 years of age) and in this particular formula, age defying (11+ years), it is even less. Again, this is to reduce the load on the kidneys. Obviously, if you have a cat diagnosed with kidney issues, you need a different diet. This formula is a preventative formula- science diet makes a Kd diet for cats with kidney disease that can be purchased through a licensed veterinarian. All older animals, even in the best of health, but most especially animals which require high protein requirements in their optimal years (and, hence, heavier kidney function than some other species), have lessening kidney function as they age. Inadequate protein can have detrimental long term effects when dealing with a young feline. However, in senior cats, decreasing the protein content keeps the kidneys from being overworked, often leading to greater preservation of kidney function durring these later years. Normally, because felines are strict carnivores, a high protein diet is a necessity. However, our domesticated felines, often, outlive "feral" felines. As a consequence, we are left to rethink dietary issues on a "short-term ' bases for these more senior animals (they have less years ahead than behind them). It is just a consequence of the aging process. In general, most felines will develop kidney issues if they live to a very senior ages because of their "strict carnivore" design and the high protein requirements of that design. This formula, also, has a greater fiber content. Fiber is what "slows" food in the metabolization process- allowing time for absorption of nutrients. As animals age, our metabolism is less efficient and nutrients are not as easily and efficiently absorbed. The consequence, with regard to older animals, is that 'food" passes through the digestive system processes without the nutrients being obtained from proper digestion. This is part of the reason older animals tend to lose weight and, especially, muscle mass. Increasing the fiber intake slows down the food going through the digestive system allowing the slowing and aged body time to absorb the needed nutrients. In conclusion, I do not recommend a "Senior Diet" for a cat based just on age. Some cats may never require such a diet. A senior diet should only be considered for animals that show signs of needing a diet change.