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Physical Changes in Your Aging Cat

Heart, Lung, Kidney, Liver, and Glandular Changes

Many changes occur to your cat's internal organs as he grows older. Good nutrition and proper dental care can help maintain good health into advanced old age, but some changes are inevitable.

The aging heart loses muscle tone and can't pump blood as efficiently as a young heart. Cardiomyopathy, a disease of the heart muscle, is not uncommon in older cats. Your vet might diagnose heart problems with the help of radiographs (x-rays), or he might recommend an electrocardiogram (EKG) or echocardiogram for more precise diagnosis. Medication can often control symptoms of feline heart disease, depending on the type of disease, its severity, and your cat's general health.

Your cat's lungs become less elastic with age, reducing their ability to oxygenate blood, which reduces your cat's stamina. Older cats are prone to respiratory problems, so your vet might suggest changes to your kitty's vaccinations. If your cat has asthma, her symptoms might become worse.

Your cat's risk of kidney disease also increases with age. Part of the increased risk results from natural changes in the kidney itself, but various health problems can also contribute to kidney disease. Gum disease can result in transmission of bacteria to other organs, especially the kidney and heart. If the heart isn't working properly, blood flow to the kidneys may be reduced, contributing to kidney dysfunction.

Observable signs of kidney disease (usually increased drinking and urination) don't become apparent until more than half of normal kidney function is lost, so screening for kidney function through blood chemistry tests or urinalysis is a good idea as part of your older cat's regular examinations. Screening is also recommended before any procedure requiring anesthesia. Kidney disease is serious, but special diets and medications can often control it.

Your cat's liver, which produces various proteins and enzymes and removes toxins from the blood, also becomes less efficient with age. Liver disease isn't always easy to diagnose, though. A perfectly healthy animal sometimes shows high levels of liver enzymes, while one with liver disease might have normal levels of liver enzymes in the blood. Still, screening is recommended periodically and before anesthesia, as an animal with reduced liver function requires lower doses of anesthesia and some medications.

Glandular changes and the resulting hormone-related diseases are also common in older cats as the levels of some hormones rise and others fall. Hyperthyroidism and diabetes mellitus (see Feline Health Problems) are not uncommon in feline seniors. Routine blood tests can catch these and other diseases early, making control through drugs, diet, and other methods more effective.

Female cats who are spayed after coming in heat or having kittens—or not at all—might develop hormone-related mammary gland tumors. Although some tumors are fibrous rather than cancerous, about 85 percent of feline mammary tumors are malignant. A careful examination of the older female cat's mammary glands should be part of her regular check-up.

Hearing Loss

Hearing loss is not unusual in older cats, but it can go unnoticed for a long time, especially in a multi-pet home where the hard-of-hearing cat may rely on visual clues from other pets and continue to respond to activity as you expect him to. Our cat Mary was stone deaf, and we didn't realize it. I made the discovery when she didn't react at all when I talked to her back and no one else was around to cue her. If your cat's first reaction to seeing you looks like aggression—a startled cat reacts with a swat or bite, for example—a visit to the vet to check his hearing might be in order.

Hearing loss due to aging is usually permanent. A few changes in your behavior, though, can keep your cat's interaction with you positive. Even if your cat is completely deaf, he might be able to sense vibrations, especially on the floor or a piece of furniture where he's lounging. Clap your hands, stomp on the floor, or pat the end of the couch to give him a heads-up. If he can still see, visual signals are also effective (if he's not sound asleep). Move into his field of vision at a distance before you approach him, or flash a light on and off to get his attention.

Eye and Vision Changes

Your cat might also lose some or all of her vision as she grows older. Common signs of vision loss include bumping into things or lack of interest in moving objects. Cloudiness of the older cat's eye, known as nuclear sclerosis, is normal and usually doesn't affect vision, but cats might also develop cataracts, glaucoma, or other eye diseases. Gradual changes are fairly normal, but if you notice a sudden change in the appearance of your cat's eyes or in her apparent ability to see, contact your vet. The eye is the window not only to the soul but often to general health as well.

Behavioral Changes in Your Aging Cat

Elderly cats often undergo changes in personality and behavior. Some changes are minor or even perceived as improvements by a cat's people—Felix no longer climbs the curtains! But other changes can be problematic and worrisome. Health problems and physical changes (see “Physical Changes in Your Aging Cat”) often cause or contribute to changes in personality, behavior, and sleep patterns. In addition, many cats (like many people) become less able to handle stress as they grow older. Events your cat took in stride when he was younger might become catalysts for inappropriate elimination, aggression, phobias, and other behaviors you don't want.

Cat Nip

If your aging cat no longer seems to handle stress well, bringing home a new pet, especially a playful kitten, might not be a great idea. The best time to welcome a new pet is while the older one still moves around easily, sees and hears reasonably well, and retains an interest in his housemates.

Fortunately, behavior modification techniques and veterinary intervention can manage many age-related behavioral changes. If your old cat just doesn't seem to be herself, talk to your vet about diagnosis and treatment options.


We've probably all known some “crotchety” older people. Cats can become crabby as they age, too, sometimes behaving aggressively toward people and other pets they have lived with peaceably for years. Aggressive behavior is at best no fun to live with, and it's dangerous. Besides, a cat who changes in this way is not a happy feline.

Aggressive behavior in older cats is often a response to pain or fear. Pain might be the chronic aches of arthritis or long-term illness or the sudden pain of acute injury or disease. Fear can arise when the cat is in pain or when she can no longer see or hear well. Various organ diseases can also cause chemical imbalances that lead to behavioral changes, including aggression.

If your cat becomes aggressive, schedule a thorough physical exam to determine whether there's a medical reason for the change. If the behavior seems to be the result of a medical problem, talk to your vet about treatment options. If no obvious cause can be found for the behavior, ask your vet to refer you to a qualified animal behaviorist who can work out an appropriate treatment program. Medical (drug) treatment, other approaches, or a combination of treatments can often control aggression.


A number of medical conditions can cause older cats to lose their previously fastidious litter box habits, including feline lower urinary tract disease (FLUTD), kidney or liver disease, colitis, inflammatory bowel disease, anal sac disease, diabetes mellitus, hyperthyroidism, arthritis, or vision problems.

Loss of House Training

The most common behavioral problem reported in feline senior citizens is inappropriate elimination—pottying outside the litter box and sometimes scent marking (spraying). Such behavior might be due to a medical problem. Stress can also lead to inappropriate elimination in cats of all ages, especially older cats.

With older cats in particular, you might need to clean the litter box more frequently as changes in your cat's digestive and urinary systems cause him to use the facilities more often. If your old kitty is arthritic, he might experience pain getting to and in and out of the litter box. Sometimes a simple change—say, a more accessible location or a new box with lower sides—makes all the difference. Going up and down stairs can be painful for old joints, so adding a box or two in different parts of the house, especially if your house has multiple levels, might be helpful.

More on: Pets

Excerpted from The Complete Idiot's Guide to Getting and Owning a Cat http://life.familyeducation.com/cats/health/45708.html 2005 by Sheila Webster Boneham, Ph.D. All rights reserved including the right of reproduction in whole or in part in any form. Used by arrangement with Alpha Books, a member of Penguin Group (USA) Inc.

To order this book visit the Idiot's Guide web site or call 1-800-253-6476.


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