Written by Dr. Jill Cline, Ph.D.
Thanks to advances in veterinary care and nutrition, dogs are living longer today and remaining healthy and active well into their senior years. It is currently estimated that more than 40 percent of dogs in the United States are “mature adults” and about 30 percent of these dogs are older than 11 years of age. Understanding the nutritional needs of older dogs can help owners to continue to provide optimal care and nutrition to their canine companions throughout their elderly years.
When is my Dog Considered to be a “Senior”?
Aging starts as cells begin to break down faster than the body can repair or replace them and the body’s systems become less efficient. In dogs, the wide range in body size between breeds leads to different rates of aging. Toy and small breeds tend to live longer and age more slowly than do large breeds of dogs. Other factors that influence rate of aging include a dog’s lifestyle and fitness level, health care and nutrition, and the presence of chronic disease. A good rule of thumb is to consider a dog to be in her senior years once she is in the last third of her expected lifespan. For example, a large breed dog with an average lifespan of 11 years is considered to be in his senior years after 7 years of age. Conversely, a small or toy breed dog with an expected lifespan of 14 years is considered elderly when he reaches about 10 years of age. Although such guidelines are helpful, dogs must be assessed as individuals, using changes in activity level and health rather than chronological age to classify them as elderly.
Changes Associated with Aging
Just as in people, dogs experience certain normal changes as they age. These changes may not be the same in each dog and they do not always significantly impact a dog’s quality of life or health. Owners can help their older dogs to adapt to these changes through health care and diet, modifications in lifestyle and exercise patterns, and by diagnosing potential problems early. Some of the age-associated changes that you may observe in your dog may include:
• Reduced activity level: Older dogs tend to sleep more, play less vigorously, and require less daily exercise than younger adult dogs.
• Change in body weight or body condition: Some older dogs gain weight and lose muscle tone. This occurs as a result of a normal decrease in metabolism and reduced activity level.
• Decreased sensitivity of special senses: Some dogs show signs of hearing loss and decreased visual acuity as they age. You may notice that your dog does not hear certain noises or has trouble maneuvering stairs. Help him out by making sure that he is looking at you when you call him and taking the time to show him new objects in his environment.
• Behavioral changes: While many dogs “age gracefully” and seem to become more sweet and affectionate as they grow older, some may become more irritable or less tolerant of handling. This is often caused by health changes such as arthritis or alterations in cognitive (mental) function. If your dog’s temperament changes abruptly, seek veterinary care to check for underlying causes and to receive appropriate treatment.
• Health problems: Some older dogs develop chronic health problems such as arthritis (lameness or stiffness), dental disease (lost teeth or gum inflammation), heart disease (decreased exercise tolerance, weakness), or reduced kidney function (increased water consumption and urination, incontinence). Luckily, many of these disorders can be successfully managed through medication and diet, significantly improving an older dog’s quality of life and life expectancy.
Nutrients to Consider
The primary objectives of feeding senior dogs are to support optimal health and body condition, slow or prevent the development of chronic disease, or manage signs of any diseases that are already present. Nutrients that are of special interest include calories, protein, fat, and certain essential vitamins.
Calories: The reduced activity level of older dogs and normal changes in body composition leads to a reduction in daily calorie requirements. Continuing to feed the same amount of food can cause weight gain and overweight body conditions. For these reasons, diets designed for senior dogs have slightly reduced caloric content while still containing optimal levels of all the essential nutrients.
Protein: Contrary to popular belief, healthy older dogs do not benefit from a reduction in dietary protein. In fact, research studies have shown that older dogs require an optimal level of high quality protein that is equal to or slightly higher than levels included in adult maintenance diets. This occurs because older dogs are less efficient at utilizing protein and maintaining protein reserves in the body. Sufficient dietary protein is essential to support a healthy body condition, to prevent loss of muscle mass, and for a healthy immune system. Even mild protein deficiency can impair immune function in an otherwise healthy older dog, causing increased susceptibility to illness and physiological stress. Finally, there is no support for the belief that dietary protein contributes to kidney disease in older dogs. Reductions in dietary protein is used to manage symptoms of renal disease only after a certain level of renal dysfunction occurs. Unless a dog has clinical evidence of kidney disease or other problems for which dietary protein restriction may be beneficial, healthy older dogs do not benefit (and may be harmed) from dietary protein restriction.
Fat: A slight reduction in dietary fat is an effective way to decrease the caloric content of foods designed for less-active senior dogs. However, older dogs still require optimum levels of the essential fatty acids and may also benefit from the anti-inflammatory properties of omega-3 fatty acids. High-quality dietary fat also contributes to a food’s palatability, which is especially important in older dogs who may experience a diminished sense of smell or taste. Diets designed for older dogs should contain slightly lower fat to reduce caloric density, but still contain high quality fat with optimal levels of essential fatty acids.
Vitamins and minerals: Older dogs have the same vitamin and mineral requirements as young adults. However, because of their anti-oxidant functions, some vitamins such as vitamin E, vitamin C and beta-carotene (a vitamin A precursor), are especially important for senior animals. These nutrients support a healthy immune system and help to rid the body of “free-radicals”, harmful compounds that increase with age and can contribute to the onset of chronic disease. Finally, there is evidence that providing a diet that is enriched with anti-oxidant vitamins and related compounds can improve cognitive (mental) function in older dogs.