Good Old Dog

Signs to watch for in your aging dog
By Nicholas Dodman, June 2011, Updated February 2015

There are changes a dog goes through that have nothing to do with disease processes but, rather, are simply normal physiologic shifts. To help you distinguish aging from illness, here is a rundown of those natural, expected modifications that occur as a dog enters and passes through her geriatric years. You’ll see that many of them are similar to changes that people undergo, but which do not grip them with fear of imminent death or disability. They simply require a little more attention on the part of those caring for canine loved ones, along with an appreciation that the dog may very well need your sensitivity with regard to exercise intensity, severe weather conditions and so forth.

Graying hair, particularly around the muzzle: We think it adds character—no Clairol needed.

Slower metabolism: Older dogs burn fewer calories than they did in their younger years. Most of the decrease in metabolic rate comes simply from dogs tending to become less physically active in old age. The less active they are, the more their muscle cells go unused and therefore atrophy and die off, increasing their fat-to-muscle ratio and paving the way for frailty. Slowed physical activity, incidentally, often comes not from age per se but from conditions like obesity and arthritis, which are more treatable than ever.

Difficulty adapting to hot and cold temperatures: Older dogs are less physiologically tolerant of very hot or very cold weather. Put her in a fuzzy bed with a blanket over her when it’s cold (especially important because your dog is close to the floor, and hot air rises while cold air in the room sinks). In hot weather, make sure your pal has plenty of water and is near a source of coolness or at least shade.


Sign up and get the answers to your questions.

Email Address:

Decreased immunity: Older dogs need their vaccination shots even more than when they were young and middleaged. The immune system slows down in old age, making a dog more susceptible not only to diseases such as cancer but also to infections. She simply cannot mount a sufficient immune response to illnesses she might have been able to ward off in her younger years.

Decrease in heart and lung function: Aging dogs do not get coronary artery disease, and they do not get heart attacks. Rather, an older dog does not respond as efficiently to physiologic stress—she will experience an increase in heart rate resulting from exercise, for example. It’s the same for the lungs. As a dog grows older, some of the elastic fibers in the lungs are replaced by scar tissue, diminishing her ability to breathe as efficiently as possible.

Hormonal changes: While age-related changes vary from gland to gland, overall there tends to be some degeneration. Aging dogs have to be watched more carefully for hormone-mediated conditions such as diabetes and hypothyroidism, both of which affect the body cells’ ability to do what they have to do.

Changes in the reproductive system: There is no menopause in the canine world. But older male dogs who have not been neutered are prone to prostate problems resulting from enlargement.

Decrease in kidney and bladder function: The screenings most commonly used to assess kidney function don’t show any abnormality until a dog has already lost 75 percent of her kidney capacity, so dog companions have to partner with vets to identify signs of possible kidney disease. As far as the bladder, older females dogs, predominantly those who have been spayed, are the ones to end up afflicted with urinary incontinence.

Decrease in liver size: As a dog ages, she actually loses liver cells, which makes her liver smaller. The change translates into a decrease in liver function, which means a diminished capacity to detoxify harmful byproducts in the body.

Gastrointestinal slowdown: While GI function in older dogs remains pretty much intact in the stomach and intestines, there’s a decrease in gastrointestinal action in the mouth, which is the beginning of the GI tract. Specifically, there is a decreased production of saliva, which helps to clean the oral cavity. That in turn, contributes to the development of dental tartar and periodontal disease.

Bone loss: Dogs undergo a decrease in bone density, but they tend not to develop osteoporosis. Dogs do experience fractures but not because of decreased bone density throughout the body, like in older people.

Neurologic decline: Falloff in this area divides into two categories: a decline of the senses, including smell, sight, and hearing; and a decline in the function of brain cells. The longer dogs live, the more important it is to watch for signs of the canine version of Alzheimer’s, because the earlier it is detected, the more treatable it will be.

Article first appeared in The Bark, Issue 63: Feb/March 2011

Nicholas Dodman, BVMS, is a world-renowned animal behaviorist and the best-selling author of several books, including The Dog Who Loved Too Much, Dogs Behaving Badly and The Well-Adjusted Dog. He is director of the Animal Behavior Clinic at the Tufts Cummings School of Veterinary Medicine.