Cats become extremely finicky eaters as their quality of life declines, so I consider it a great success if we can get them to eat anything at all. Before we reach that point, however, there’s a lot owners can do from a nutrition standpoint to maximize their cat’s health and longevity.
A cat’s digestive physiology changes as it gets older. Around the age of 11 or 12, the ability to digest fat starts to decline. Fats contain more calories per gram than do either proteins or carbohydrates, so this can have a major effect on an older cat’s ability to extract calories (energy) from food. To make matters worse, research has shown that around 20% of cats over the age of 14 have a reduced ability to digest protein. Put these two conditions together and without dietary intervention, a cat will lose both fat and muscle mass. The loss of muscle mass is especially concerning because these individuals are at increased risk of illness and death.
Most older cats also have some degree of arthritis and are at heightened risk for kidney disease. Advanced age also increases the production of free radicals within the body. A free radical is “a group of atoms containing oxygen and electrons that can alter and damage the chemical structure of cells or other compounds.”
Free radicals essentially “steal” electrons from whatever is nearby. When another molecule is forced to give up an electron, it often becomes a free radical itself, which continues the cycle of cellular injury.
Based on all this, a good diet for an older cat has the following characteristics:
- High antioxidant levels (e.g. Vitamins A, C, and E, beta carotene, and selenium) to counteract free radical damage.
- Low levels of phosphorus to protect the kidneys. High quality protein sources contain less phosphorous than do those of low quality.
- Enough protein to maintain a cat’s muscle mass. Extra carnitine (an amino acid) can also help in this regard.
- Fish oils and other sources of essential fatty acids to counteract the effects of brain aging and promote joint health.
- A moderate to high level of fat, based on a cat’s body condition score. Skinny cats need a lot of fat to maximize their caloric intake. Overweight cats can do with a bit less.
- And last, but certainly not least, excellent palatability and smell to stimulate the appetite.
These recommendations can certainly change if an older cat suffers from a disease that is managed, at least in part, through diet. Ask your veterinarian to help you determine which particular food might be best for your cat based on its individual needs.