Canine Healthy Aging Versus Illness

How to make sure old does not become sick.


If you go strictly by the numbers, “geriatric” is the point at which 75 percent of one’s anticipated lifespan has passed. So for a dog expected to live to age 14, that would be 10.5 years.

But thanks to advances in veterinary care, old does not have to mean “feeble” or “frail.” Just as white-haired people in their 70s and 80s now go on hiking treks all around the globe and lead full, active lives (something that was largely unthinkable before modern medicine stepped in to preserve health as the years advance), today old dogs often live healthily till very near the end of their lives — romping, playing, and acting like the complete goofballs they always were.

It goes back to the question baseball great Leroy “Satchel” Paige once asked: “How old would you be if you didn’t know how old you was?” That is, age is a number, not an indicator of health — or sickness.

Of course, there’s no denying that illness is more common in older dogs. Diseases like cancer, kidney disease, and heart disease are what eventually lead to death in our pets. But that’s just it. Old age itself is not a disease, and no dog (or person) ever dies from it.

That said, there are changes a dog goes through that, while not about disease processes, are normal physiologic shifts that occur over the course of the lifespan. But how do you distinguish between those shifts and actual sickness? Even more to the point, what can you do to make sure those shifts don’t become sickness? Following, a rundown of the natural, expected physical and physiologic changes that occur as a dog passes from middle age to her geriatric years — and how you can hold them back as mere changes for as long as possible so that they do not become about death and disability. Often, the antidote is simply about a little more TLC on your part. That’s frequently all it takes to slow or accommodate an age-related change and keep your dog in top condition longer.

Graying hair. A dog’s hairs, just like a person’s, start to turn gray in later years. But while the graying of human hair is most noticeable on the top of the head, on a dog that graying tends to occur right on the face, around the muzzle in particular. This one is absolutely nothing to be concerned about. Embrace the distinguished look born of your dog’s experience — lean into the nobility that her gray hairs confer on her.

Slowing metabolism. Older dogs, like older people, burn fewer calories than they did when younger. Part of the reason is a decrease in cell turnover and a slower movement of bodily substances within and between cells. In other words, there’s a slowing of activity on a biological level. In addition, dogs, like people, develop a higher fat-to-muscle ratio as they age, and fat burns calories more slowly than muscle does. Finally, the heart, lungs, and the rest of the cardiovascular system “calm down,” so it needs fewer calories to sustain itself.

Antidote. A dog can slow metabolic decline — as well as remain stronger and fitter — if you help her hold onto muscle mass through physical activity. Even dogs who have become obese or have developed arthritis can become more active through medical advances including drugs and surgeries and thereby build up some lost muscle and increase metabolic rate anew.

Difficulty adjusting to hot and cold temperatures. Chicago is mired in a deep freeze for weeks on end. The temperature in Phoenix won’t drop below 100 degrees. Who’s dying from hypothermia or heat stroke, or at least ending up in the emergency room? The elderly.

It’s the same with dogs. They become less physiologically able to adapt to extremes in temperature with advancing years. It’s normal — but it’s not comfortable, and it can lead to unnecessary illness.

Antidote. This one’s simple. First, keeping in mind that dogs age much faster than we do, remember that just because your pal was able to go jogging with you in 85-degree weather when you were 52 and she was three doesn’t mean she’ll be able to when you’re 59 and she’s 10. Seven years for you is half a lifetime for her.

Furthermore, coddle her, temperature-wise. If it’s cold out and you lower the thermostat at night, put your pet in a fuzzy dog bed with a blanket over her. (Hot air rises, and cold air sinks. It’s even colder on the floor than on the bed or couch.) You can even get her a heating pad — they make them especially for dog beds.

In hot weather, always have cold, refreshing water available (throw in a couple of ice cubes), and make sure your dog can get into the shade if she’s outside.

Decreased immunity. 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 won’t be able to mount a sufficient immune response to illnesses she might have been able to ward off when she was younger.

Antidote. Be vigilant about vaccinations. A lot of owners skip vaccinations in a dog’s later years, deciding that their dog has already been vaccinated against various illnesses many times and has not gotten sick, so why put the animal through more shots? The thing is, older dogs need their shots even more than when they were in their young and middle-aged years. Consider that we have seen many older dogs who were not up to date on their vaccinations become sick with parvo virus. They get it from an unvaccinated puppy introduced into the household or because they are allowed to continue to roam where unvaccinated puppies might romp. The upshot: the parvo virus attacks the GI tract and immune system and causes severe vomiting and diarrhea. It can also cause a secondary bacterial infection that spreads from the GI tract to the rest of the body, sometimes resulting in death. It’s all the more tragic precisely because the scenario could have been avoided with routine care. Your older dog’s vaccination schedule must be maintained.

Decrease in cardiovascular function. As a dog ages, she doesn’t have the same cardiac reserve needed to respond to physiologic stress, such as an increase in heart rate resulting from intense exercise. It’s the same with lung capacity. As a dog grows older, some of the fibers in the lungs that allow them to expand and contract with each breath are replaced by scar tissue, and that diminishes her capacity to breathe as efficiently as possible. There is also less capacity for oxygen to cross from the air into a dog’s lungs and then to the rest of her body.

Antidote. While bearing in mind that an older dog can’t tolerate temperature extremes well, remember that her capacity for vigorous physical activity in general is going to decline. Five to seven years is a long time in her life — keep her moving, yes, but slow up the pace for her.

Hormonal changes. The glands that secrete the body’s hormones are called the endocrine system. Age-related changes vary from gland to gland, but overall there tends to be some degeneration. For instance, insulin might not be produced as efficiently to make sure sugar is cleared from the bloodstream after food has been eaten. “Normal” for thyroid hormone values changes in old age, too.

Antidote. Don’t slide on your dog’s annual or semi-annual wellness exams. Changes in hormone activity don’t necessarily translate to disease states, but you want to stay on top of things and have your dog watched for endocrine illnesses so that if one takes hold, it is treated as early as possible in order to do the least damage.

Gastrointestinal slowdown. You hear “gastrointestinal,” and you might think “stomach” or “intestines.” But a GI slowdown might affect an older dog’s teeth. Consider that GI function in an older dog’s stomach and intestines actually remains pretty much intact. It’s in the mouth, which is the beginning of the GI tract, that activity begins to fall off. Specifically, saliva production decreases. That’s key because saliva cleans the oral cavity. The less clean the mouth, the more likely problems with the teeth will take hold in the form of gum disease. That can make eating difficult and can also eventually cause teeth to fall out.

Antidote. Make sure your older dog gets regular oral check-ups along with her routine exams, and let the vet perform a teeth cleaning under anesthesia if she recommends it. That will clean away the plaque and tarter that lead to tooth erosion. These days, veterinary dentists can even perform complicated procedures like root canals in order to save a tooth. Older dogs no longer have to walk around in dental pain, and they don’t even necessarily have to have a compromised tooth pulled.

Of course, if you brush your dog’s teeth every single day, that will reduce the likelihood that she’ll need costly teeth-saving procedures.

Decreased liver size. As a dog grows older, she loses liver cells; the liver literally shrinks. That means the liver is less able to do one of its main jobs, which is to break down toxic substances. The result on the ground: a dog will not be able to metabolize, say, a drug dose as well as when she was younger. Even dietary supplements may be metabolized more slowly in an aged dog. It doesn’t mean your dog will necessarily suffer because of decreased liver capacity. But it’s a possibility.

Antidote. Be up front about any supplements or other substances you are administering to your pet so your vet can take that into account when assessing the animal’s liver burden. There’s no direct test for liver function, so there’s no precise formula for deciding when the work the liver is being asked to do has become unduly burdensome. But various blood tests, considered in combination with a dog’s age, will allow for a reasonable estimate of the safe upper limits for supplements, drugs, and other substances.

Decreased kidney activity. It’s simply a function of age. Each of a dog’s (and person’s) two kidneys is comprised of thousands of subunits called nephrons that help filter waste from the blood and send it out of the body in urine, and the older the dog, the less well those nephrons do their job. That’s okay, but if out-and-out kidney disease develops, it’s a very serious issue. Unfortunately, most commonly the screenings available for kidney function don’t pick up any abnormality until a dog has already lost 75 percent of her kidney capacity. In other words, a dog’s kidneys could be in bad shape even though the numbers on a lab test might look normal.

Antidote. If you see your older dog passing larger volumes of urine than she typically has and particularly if the urine is more dilute than usual, get her to the doctor. One of the first things that happens when the kidneys begin to fail is that they lose their ability to preserve the body’s water by concentrating the urine.

As your dog urinates more, she’ll drink more. Of course, there are lots of conditions that cause a dog to drink more — diabetes and Cushing’s disease, for example — but the sooner you get her into the exam room and diagnosed, the better the chances that if she does have kidney disease, it can be managed more effectively because it will have been caught sooner rather than later.

Neurologic fall-off. Decline here could translate as a decline in the senses or a decline in the function of brain cells. Both happen in old age. It’s the degree to which they happen that determines whether there’s a problem.

Antidote. Don’t jump to conclusions. A decline in the function of cells in, say, the ear canal can lead to hearing loss, and a loss of hearing can lead to behavior that looks like senility but isn’t. That is, just because your dog no longer turns around when you call doesn’t automatically mean she is failing mentally. Take her to the vet for a thorough workup. Whatever the problem, the earlier it’s caught and treated, the less damage it will do, and the farther down the line it will do it.


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