As cats age, their nutrient needs change too. Cat owners should pay close attention to changes in their cat and consult with their veterinarian about signs of aging. A commercial cat food designed for senior cats will be formulated with these changes in mind to ensure proper health and longevity for older cats. Regular veterinary visits, exercise, and mental stimulation are all key to maintaining proper health throughout your cat’s later years.
The geriatric cat population has increased in recent years. Between 40 to 50% of the cat population is currently considered seniors. The reasons for the increased number of senior animals include the movement from rural to urban areas and the increased number of pets kept inside compared to outside. Farm or feral cats have a lifespan of only three to five years compared to house cats, which can live about three times longer. Improvements in health care such as vaccine programs, medications, and control of infectious disease have all decreased illness in pets and increased their lifespan.
As animals age, we see both obvious signs of aging as well as less obvious ones. The obvious external signs include a graying hair coat, slowing movements, decreased activity, changes in body condition, and a decrease in the sensitivity of hearing, sight, and smell. In addition, for some animals, internal changes occur in organ function, and there may be decreases in liver, kidney, and gastrointestinal function. There may also be decreased immune system responsiveness. These changes can affect the nutrient needs of the animal as it ages.
Changes in dietary management should occur as a cat ages. When feeding geriatric or senior pets, we should consider specific goals, such as:
Choosing a commercial food designed specifically for senior cats will ensure that these changes are made.
Unlike dogs, size or breed does not determine the age at which a cat becomes geriatric. Dogs have distinctly different lifespans related to the large range of adult body weights seen. Cats begin to have age-related changes at approximately 7 years of age.
Cats have four distinct life stages related to age, and owners should feed them accordingly. Cats should be fed for growth for the first year of life. During their adult phase (from age 1 to 7 years), they should be fed for general maintenance of weight. Finally, the cat has two senior or geriatric stages. The first phase, labeled as mature, lasts from 7 to 11 years of age. During this phase, the beginning of age-related changes in metabolism occurs. After 12 years of age, another shift in the metabolism of the cat occurs, resulting in the final geriatric phase.
Unlike dogs, the energy requirements of cats do not decrease with aging. Dogs have an age-related decrease in activity, while cats maintain a relatively sedentary lifestyle throughout their lifespan and see little decrease in activity with aging. It is important to maintain activity level in your cat as it ages. Physical stimulation such as structured play or walks is important to maintain the overall health of your senior cat. Additionally, providing mental stimulation will help to maintain your cat's cognition, which often decreases with aging. Data have suggested that increased dietary antioxidants and omega-3 fatty acids may also assist with maintaining mental cognition.
As a cat ages, distinct changes in body composition occur. The primary cause for the distinction between mature (7 to 11 years old) and geriatric (over 12 years old) cats is the cat's body composition. A key study in age-related changes of cats was conducted with cats housed in the Nestle Purina Research Center. The body weight and body composition were measured throughout their lifespan. Body weight remained relatively stable through the adult phase (1 to 7 years of age). During the mature phase, the body weight of cats increased by over 2 pounds, while geriatric cats tended to lose weight up to approximately 1.3 pounds less than in the adult phase. This is indicative of the inability of very old cats to maintain normal body weight.
Additionally, body fat and body protein change as the cat ages. During the adult phase, cats should be at their ideal body condition in terms of fat and lean muscle mass. During the mature phase, when cats are at their highest weight, an increase in body fat and a drop in the proportion of body lean (muscle mass) occur. During this phase, cats are at the highest risk of obesity. Ideally, cats should be maintained at a body fat less than 30%. Body condition scores should be recorded for your cat on a regular basis to prevent obesity. Once a cat is over 12 years old, the decrease in body weight results in both a decrease in body fat and an increase in body lean. These cats tend to be underweight and poorly muscled.
In addition, as cats reach the mature and geriatric phases, a decrease in digestive function resulting in lowered protein and fat digestibility may occur. This is particularly true for cats over 12 years of age. Geriatric cats may need additional protein in the diet to meet their nutrient needs as they will be able to use it less efficiently than when younger.
When choosing a diet for mature and geriatric cats, keep in mind that the cat can consume the same number of calories but should be closely monitored for changes in body condition. Mature cats (7 to 12 years old) are more likely to become obese and may need to be fed limited diets to maintain ideal body condition, while geriatric cats (>12 years old) may lose weight and will need added calories in their diet to improve body condition. Close attention should be paid when feeding geriatric cats. They are less able to digest the protein and fat in their diet and may lose lean body mass.
They should be fed a more palatable, highly digestible diet designed for senior cats. A canned food that is particularly strong smelling may improve feed intake in cats that have failing senses of taste and smell. The diet should also contain adequate protein levels. Cats have a higher requirement for protein than many other mammals due to their carnivorous nature. With the loss of lean muscle mass due to aging, geriatric cats may need to consume more protein to decrease body protein losses. However, cats need to be monitored by your veterinarian as they reach their senior years to ensure proper kidney and liver function. If decreases in kidney function begin to occur, your veterinarian may place your cat on a lower protein diet as high protein can add stress to the kidneys.
Nutrient needs change with aging in the cat. Paying particular attention to body condition score may help to prevent or decrease the onset of age-related diseases. Choosing a high-quality diet designed for mature and geriatric cats may help to improve the quality of life in the aged cat. Regular veterinarian checkups (every six months) will aid in monitoring age-related changes in body composition, health status, and organ function. Providing proper exercise and mental stimulation is also beneficial to the senior cat.
Lisa Karr-Lilienthal, Ph.D. - University of Nebraska-Lincoln