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Aging Pets

Diseases of Aging Dogs and Cats

A few years ago at a family gathering, my aunt, who had just finished telling one of her famous cat stories, proclaimed, “ All of my cats over the last 25 years have gotten kidney disease. There must be something in the water.”

Now, a regular cat enthusiast off the street may have been swayed by her proof; however, as her relative and as a veterinarian, I knew she had left out a vital bit of information—that all of her cats had lived to at least 13 years of age.

Realistically even if your cat or dog is as healthy as an ox throughout his first decade of life, at some point when he reaches the senior state, he’s going to get sick and various organs are going to start to fail. In cats, that organ is often the kidney.

Kidney Disease in Cats

Says Dr. Alan Stewart, an internal medicine specialist at San Francisco Veterinary Specialists in San Francisco, “Kidney problems are probably the most common disease affecting older cats. Anyone with a cat older than 10 years of age should be on alert for this disease.”

Knowing what to look for is essential because signs can be subtle. Says Stewart, “Often the first sign is increased water intake.” When the kidney is damaged it can’t regulate water balance. As a result, the cat excretes excess urine and has to make up for the loss by drinking more.

“Most clients don’t recognize this as a major problem,” says Stewart. “They think the increased drinking is a good thing. But cats evolved as desert animals so, generally, it’s abnormal to see them drinking.”

To keep track of water consumption, Stewart encourages clients to measure the amount of water at the beginning and end of the day and notice whether they see cats drinking at the water bowl. “If clients miss these early signs, the cat instead tends to come in due to reduced appetite and weight loss,” says Stewart. These signs occur because the damaged kidneys are unable to remove waste products from the blood, which leads to waste build-up and a cat feeling sick.  It’s like a mild version of food poisoning or a hang-over.

While it is important to watch for signs of kidney disease, veterinarians generally recommend cats have yearly bloodwork done starting around 10 years of age. When the waste product, creatinine starts creeping up, cats can be placed on a prescription kidney diet to slow the disease progression. Cats on these diets can double their remaining lifespan. These diets are low in protein and phosphorus, with protein levels that are much lower than any over-the-counter diet. Says Stewart, “It is important to almost think of these prescription diets as drugs. That is why they require a prescription!”

So why not put all cats on a prescription kidney diet regularly? Stewart answers, “There’s no evidence that they prevent disease from occurring in cats without renal disease, and they are more expensive than regular store foods.”

Cats with kidney disease should be checked by a veterinarian, have blood work and urine tested, and should have their blood pressure measured every 3–4 months.


One can’t over stress the importance of a yearly exam and bloodwork in the older cat. You might be surprised with what you find. A coworker named Sara recently asked me for behavior advice regarding her 11-year-old cat that had suddenly started urinating outside the box. Generally this type of behavior is related to stress, change in routine, poor box cleaning, or other behavioral and environmental issues. But when it occurs suddenly in an older cat with no obvious environmental change, a thorough exam and bloodwork are the first steps.  Within a day, we had the answer. Sara’s cat had hyperthyroidism, the most common endocrine disease in the older cat.

Hyperthyroidism is basically an enlarged, overactive thyroid gland.  Like kidney disease, it can cause increased water intake and weight loss, but, unlike kidney disease, these cats tend to be ravenous. Some cats can also present as being highly agitated, grumpy, or mean. These signs were more common a decade ago when veterinarians weren’t catching the disease so soon. Says Stewart, “Now we catch them when their thyroid hormone levels are 5–7 units rather than in the 15 range like we saw 15 years ago.” On physical examination, the veterinarian may be able to feel enlarged glands running along the trachea, or windpipe.

Untreated hyperthyroidism can be lethal since it’s associated with elevated heart rate and abnormal rhythms. Additionally the ensuing hypertension can cause other important physiologic changes. Fortunately, the disorder is straightforward to treat. One can choose either a daily pill to keep the thyroid gland in check for the rest of the cat’s life or irradiation of the enlarged glands. Sara chose daily pills for her cat—a much simpler solution than the behavioral modification and detective work that might have been required, instead, had the problem been purely behavioral. For cats that don’t easily take their pills, clients can use various methods to trick them into taking it or they can train the cat to enjoy receiving medications.

For dogs, growing old comes with its issues too.

For dogs, cancer is one of the most common afflictions seen in the senior years. Unfortunately, there’s no one specific cancer for which to be on the lookout; rather, there are many types. This is why an annual exam and geriatric screen as well as attention to changes in your dog are important. One common presentation for a common cancer is sudden appearance of masses under the skin due to lymphosarcoma. These masses are enlarged lymph nodes and they can suddenly grow to golf ball size within a day. Treatment can cause the signs to subside equally as fast and with minimal side effects to the dog.

Other times, indicators of cancer are more subtle or generalized. My parent’s Scottie showed gradual aloof behavior. Meggie would hide when they called her instead of coming when called like she used to do consistently. Ultrasound of her abdomen revealed an enlarged spleen and a sample of the spleen revealed lymphosarcoma again. Tests of her blood and other organs showed no evidence of spread so a splenectomy was performed. Her recovery from surgery was swift and for several months Meggie was back to her normal self. Although the effect of surgery was short-lived in this case, the quality of time she enjoyed for 3 months was priceless.

Older dogs and cats may develop other non-fatal but debilitating issues.

For instance, as with older people, at some point the hearing and vision go. With dogs, the hearing loss is most noticeable in trained, well-behaved pets. First, they start acting confused when you call them and often head in the wrong direction. Later, as hearing loss progresses, the once well-behaved dogs fail to come when called. So, if your older dog appears to be less attentive or responsive to your cues, rather than getting angry, consider that he may actually be going deaf. The “searching behavior” that accompanies hearing loss often leads to the incorrect conclusion that poor vision is the problem. While it is difficult to objectively evaluate hearing, vision can be assessed by an ophthalmologist.

Two other issues have to do with sight. According to Dr. Cynthia Cook, a veterinary ophthalmologist at Veterinary Vision in San Francisco, “To the casual observer, the eyes of most dogs over 9 years of age have a bluish or cloudy appearance. This cloudiness may be caused by cataracts or a normal, aging change, nuclear sclerosis. Distinguishing between the two may require specialized equipment and an exam by a veterinary ophthalmologist.” With nuclear sclerosis, the lens fibers, which are produced throughout the life of the dog, become more dense, much like rings in a tree. Because the lens capsule can’t expand, the lens becomes more rigid and less flexible which impairs the ability of the eye to focus. The condition is analogous to presbyopia or loss of near vision in humans, which occurs to all of us as we reach middle age. Luckily, blurred close-up vision doesn’t affect dogs as much since they don’t read newspapers, sew, or send text messages. However, it does affect their depth perception; vision-impaired dogs may easily run up stairs or jump into the car but hesitate going down stairs or jumping out of a car. Additionally, says Dr. Cook, “because dogs developed as predators, they naturally target movement and don’t recognize stationary objects – even you! This inability to target stationary objects becomes more apparent as dogs age. Try calling your dog and moving so he can recognize you. And lastly, as in older people, night vision in older dogs deteriorates due to a slowly progressive loss of the rod photoreceptors. Rarely does this result in any significant impairment.

While nuclear sclerosis is a normal aging change, cataracts are a disorder that often progresses to blindness. Dogs with large cataracts have significantly impaired vision. For instance, if you have a dog that could once catch 10 out of 10 treats and now only catches 3, vision may be the problem.  A visit with an ophthalmologist, who has specialized equipment, can diagnose a cataract. Early diagnosis is important as cataracts can cause other changes within the eye that, if untreated, may prevent successful cataract surgery.

High blood pressure in older cats, mentioned above associated with renal disease, can also cause blindness due to retinal detachment. Often the hypertension is first diagnosed by the ophthalmologist when a cat suddenly becomes blind. Early diagnosis and treatment is often successful in controlling blood pressure and restoring vision.

Arthritis: Perhaps the most common debilitating disorder is aging dogs is arthritis. Says Dr. Carla Salido, a board-certified surgeon who also practices holistic medicine, “I worry about any patient brought in for slowing down.”   People often notice issues like difficulty getting up or lying down, but they may not notice the other signs. For instance, when my toy-obsessed Australian Cattle Dog Rudy reached 16 years of age, instead of carrying his frisbee for his entire three-mile walk, he decided to drop the toy 2 blocks into the walk. After that, he was also only mildly interested in playing fetch on walks. Most people would see this as a drop in energy level, but the real issue was pain.   Salido brings up a case with her own dog too. “My own older dog was groaning when laying down and getting up. She was still playful, went for walks, ate well and otherwise seemed fine for some time. But then she started showing lameness.” That’s when Salido took her in for diagnostics, which revealed that she had elbow arthritis. When she was treated for the arthritis, the groaning stopped.  Salido points out that if dogs are playful when they are young, they often stay playful into older age. But if they don’t want to go for a walk anymore or their energy decreases, and they sleep a lot more or can only go a fraction of what they wanted to do before, then consider arthritis or another problem causing them discomfort and pain.

A lot of people don’t know that there are things that can be done to help their older dog and cat. They just assume it’s aging. The treatments include weight loss if the pet’s overweight and NSAID drugs. There are also many other treatments available, such as a number of nutraceuticals, which are dietary supplements. These include omega 3 fatty acids and glucosamine and chondroitin, which have been proven to have anti-inflammatory effects. You may want to ask your veterinarian about a reliable source, because nutraceuticals are not regulated by the FDA. Various products may have only a fraction of the active ingredient that they claim to have.   Both Stewart and Salido recommend a holistic approach too. Acupuncture can be helpful as well as osteopathy, a manual therapy that treats altered function of the musculoskeletal system (muscles, joints and bones) to enhance health and relieve pain.

Overall, we no longer should just assume that our ailing aging pets are “just getting old.” By recognizing the early signs of disease we can take action to make our pets more comfortable and hopefully slow the progression of their disorders.


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