Dog owners should pay close attention to changes in their aging dogs and consult with a veterinarian about those changes. Included are their dogs' changing nutrient requirements.
Commercial pet foods designed for senior dogs are formulated with these changes in mind to ensure proper health and longevity for older dogs. These foods, along with regular veterinary visits, exercise, and mental stimulation, are key to maintaining proper health throughout your dog’s latter years.
The age at which a dog is considered senior depends in part on the breed. Smaller breeds tend to have longer life spans and, therefore, are not considered senior until a slightly older age. Large- and giant-breed dogs have shortened life spans and are considered seniors earlier. For example, a Great Dane has an average life span of nine to 10 years and would be senior at 6 years of age, while a Lhasa Apso has an average life span of 15 years and is considered senior at 11 years of age. A general rule is that a dog in the last third of its life span is considered senior.
Many nutritionists recommend switching to a senior diet at age 7. This is the age at which many average-sized dogs would be considered senior and the age at which we begin to see age-related changes in the metabolism and activity level of dogs. As animals age, we see both obvious signs of aging as well as less obvious signs. The obvious external signs include graying hair coat, slowing movements, decreased activity, changes in body condition, and a decrease in the sensitivity of senses such as hearing, sight, and smell.
In addition, for some animals there are internal changes that occur in organ function, and there may be decreases in liver, kidney, and gastrointestinal functions. There may also be decreases in immune system responsiveness. Senior dogs should have regular veterinary visits every six months to track age-related changes in organ function or overall health. By having regular veterinary visits, changes can be identified early, which can help in treating dogs more effectively. Your veterinarian may run blood work to determine organ function in your pet. Often age-related decreases in kidney or liver function are not apparent to the owner until significant damage has already occurred. Early detection is key to decreasing the symptoms and improving the prognosis.
When feeding geriatric or senior pets, specific goals should be considered. A diet for senior animals should be designed to enhance the animal’s quality of life, delay the onset of age-related diseases, and, hopefully, extend the animal’s life expectancy. In addition, senior dogs are more prone to disease and joint damage. Diets for senior dogs should aim to delay the onset of disease or slow its progression. Finally, a diet should maintain the animal at an optimal weight. The goal for calorie intake for senior dogs should be around 95 kcal/kg0.75, the energy requirement of an inactive pet dog. Pet food companies design senior dog foods with these goals in mind, so choosing a diet specifically for a senior dog will give you the peace of mind that the diet will best meet your dog’s changing needs.
In general, most senior dogs are less active than younger dogs, causing their calorie needs to decrease. Typically, the decrease in energy needs is about 20 percent. Senior dog foods should be lower in calories to prevent obesity in senior dogs. As dog’s age, their total body fat tends to increase. Increases in body fat can lead to obesity, which adds increased stress on internal organs, such as the heart and lungs, which may already be compromised with aging. Maintaining ideal body weight is particularly important as many senior dogs may begin to see age-related joint problems such as arthritis. Excess weight can increase the effects of this disease. In addition, senior dogs should be exercised regularly. Exercise can delay the onset of age-related symptoms and can aid in maintaining an ideal body weight.
The total body protein of dogs decreases with age due to muscle mass loss. To help prevent this, the diet should contain ample amounts of available protein and the animal should be kept as active as possible. Protein levels in the diet should be high enough to replenish muscle mass and loss of protein stores in the body. When the dietary protein level is too high, it can add stress on the dog’s kidneys if they begin to lose function. Your veterinarian should monitor your dog’s kidney function. If losses in kidney function are noted, he or she may recommend a lowered protein diet.
Other nutrients to consider in the diet of geriatric dogs include some specific vitamins and minerals. It may be beneficial to decrease the levels of sodium (Na) and potassium (K) in the diet. While heart disease develops differently in dogs than in humans, some data suggests limiting Na and K may decrease some health risks. Additional zinc (Zn) above the requirement has been shown to improve the immune response in animals. This may benefit geriatric animals with decreased immune capacity.
Mental cognition can decrease with aging in dogs, as well. To limit losses in cognition, dogs should be mentally stimulated throughout their lives. This can be done through continued training and exercise and by providing toys that are mentally challenging. Dietary changes are made in commercial senior dog foods that can also assist with maintaining brain function. Increased levels of antioxidant vitamins A, C, and E can help protect against oxidative damage, which increases with aging. Omega-3 fatty acids can assist with maintaining cognitive function.
Nutrient needs change with aging in the dog. Paying particular attention to the body condition score of the animal may help to prevent or decrease the onset of age-related diseases. Choosing a high-quality diet designed for senior dogs may help improve the quality of life in the aged dog. Maintain routine visits with your veterinarian throughout your dog's life to spot changes related to premature aging. Exercise and continuing activities that stimulate your dog both physically and mentally help to increase your dog’s quality of life.
Lisa Karr-Lilienthal, Ph.D. - University of Nebraska-Lincoln
