Mature adult and senior pets are a significant proportion of your patient population. Approximately 44% of dogs and cats in the United States are 6 years or older, and about one-third of these pets are 11 years or older.¹ Naturally, many of these patients are cherished family members whose owners are committed to providing them with the best of care, including optimal nutrition. Veterinarians are in the best position to evaluate the nutrient needs of their aging patients and to provide owners with guidance about optimal nutritional support and proper food selection.

When are pets considered mature adults and when are they "seniors"?

The wide range in size and body type among dog breeds can result in significantly different life spans. Large-breed and giant-breed dogs have life spans that average several years less than those of moderate-sized dogs.² According to one reference, giant breeds were classified as seniors when older than 7 years and large breeds were classified as seniors when older than 9 years, compared with 10 years for medium-sized breeds and 12 years for small and toy breeds.³ Cats may be considered mature adults or middle-aged when 7 years and older, seniors when 11 years and older, and geriatric when 15 years and older.⁴ It is important to note that age-related changes may occur before signs of aging are apparent to an owner. For this reason, specific nutrition for older pets should be recommended earlier than when pets are typically considered to be senior, and, for dogs, breed size should be considered. For toy-, small-, and medium-sized dog breeds, as well as cats, age-related changes may start occurring during the mature adult years, and this third midlife stage begins around the age of 7. For giant- and large-sized breeds, the mature adult life stage begins earlier — about 5 to 6 years of age — because of their shorter life spans. Nutritional needs of older pets may not remain static, and an individual's body condition, activity level, and overall health and the presence of chronic disease should always be considered when assessing the need for age-related dietary changes.

Nutritional needs of aging pets Several physiologic changes are associated with aging in animals. These include reduced activity level, a decrease in the body's lean muscle mass, and an increase in the proportion of body fat. Some dogs and cats show signs of hearing loss and decreased visual acuity as they age. Changes in the senses of smell and taste can result in less interest in food and subsequent weight loss. Skeletal and organ changes develop in some animals. These may include mobility problems (most commonly osteoarthritis), periodontal disease, compromised renal or heart function, cognitive dysfunction, and neoplastic disease. Collectively, age-related changes can alter an animal's daily energy needs, change the amounts and type of protein and fat needed, and modify the levels of minerals and vitamins required. The inclusion of functional nutrients such as glucosamine and chondroitin sulfate for joint health, prebiotics for healthy digestion, and ingredients such as L-carnitine to help maintain ideal weight and body condition and sodium hexametaphosphate to help slow tartar buildup in dogs should be considered for their health benefits.

Energy: Most older pets experience a slight to moderate reduction in daily energy needs. For example, a study found that dogs older than 8 years consumed 18% fewer calories than breed-matched dogs that were less than 6 years old.⁵ While less pronounced, a decline in energy requirements also occurs as most cats age. Regardless of these trends, older pets vary greatly in their energy needs, which are influenced by individual temperament and activity level, the presence of degenerative disease, and the animal's ability to digest and assimilate nutrients. Thus, caloric intake should be carefully monitored in older pets to ensure adequate intake of calories and nutrients while avoiding overweight conditions.