By Amy D. Shojai, CABC

Cats grow very quickly during their first 12 to 18 months of life. Their bodies build new tissue and repair injuries at a rapid rate. That fast growth slows and stops once adulthood is reached. Yet even when the cat has stopped growing, nothing is static at the microscopic level. Cells are continuously created, function a short time, then die and are replaced naturally. Organs such as the liver have built-in redundancies and reserves that allow the healthy cat to adapt to both internal physical stresses as well as those from her environment.

The older the cat gets, the less her body is able to replace cells that die. This interferes with the ability of the cat to maintain health or recover from illness. Normal reserves are depleted when cell turnover slows down or stops altogether.

The aging cat's old organs can't keep up as well with normal demands. Because these systems are interrelated, a deficit in one part of the body can cause problems elsewhere. For instance, the aging heart has a harder time pumping blood, and blood vessels begin to lose elasticity, and the combination contributes to high blood pressure. This, along with reduced oxygen getting to the brain, may add to behavioral changes often attributed to senility.

The aging process is not fully understood. One theory suggests that cells can replicate-reproduce themselves-only a certain number of times. This genetic aging is dictated by the cat's breed and inherited tendencies from her family. Just as in people, members of certain families tend to live longer than others. Siamese cats often enjoy a very long lifespan, whereas Persians seem to have a shorter lifespan than some other cat breeds.

Many experts believe oxidation influences the speed at which cells age. Oxidation is a normal part of living. The cells of the body swim in oxygen, which is necessary for many normal functions. But prolonged exposure to oxidation causes cats to age prematurely and develop disease, in the same way that metal oxidizes or rusts when exposed to air.

How does oxidation occur in cells? Their energy is produced through respiration by mitochondrion, tiny structures inside each cell which are rich in fats, proteins and enzymes. This energy-generating process also creates highly unstable and reactive atoms and molecules called free radicals. Oxidation in living tissue results when free radicals try to combine with normal atoms and molecules of the cells. This damages the cell walls and DNA, causing disease and accelerated aging.

Aged cells are less efficient. Old mitochondria are less efficient and produce less energy but generate more toxic free radicals, says Dr. Blake Hawley, a veterinarian with Hill's. "The nervous system tissue is especially vulnerable to attack by free radicals. It's really important that as the cell ages, we find ways to absorb or attack those free radicals that are produced."

Other influences outside of genetics also speed up the aging process. For example, diseases caused by feline leukemia virus and feline immunodeficiency virus suppress the immune system and make cats prone to other diseases including certain kinds of cancer and fungal infections such as ringworm. Exposure to sunlight and toxins in the air, water, or food are considered environmental influences that impact aging. Injuries, such as a fracture, speed up the age-related joint degeneration known as arthritis. Improper nutrition can interfere with cell regeneration. Emotional stress suppresses the immune system and allows damage from parasite or viral infections, which can irreparably damage the body and contribute to early aging.

In sum, each system of the body provides support for the whole. A misstep by one can prompt interconnected problems all across the body. Whether sudden, or slow and insidious, the various changes in the different body systems collectively contribute to how your cat ages.

That also means that paying attention to one age-related issue can influence the entire body to get better. You can often slow down the entire aging process simply by paying attention and addressing problems promptly as they occur. Aging is inevitable, but you can help your cat do so with grace.

Excerpted from:
Complete Kitten Care
2010 Second Edition, Amazon Kindle Publication
Chapter 2: The Aging Process

2002 & revision 2010 Amy D. Shojai, CABC

Amy D. Shojai, CABC is a certified animal behavior consultant, and author of 23 pet care books including Complete Kitten Care and Complete Care for Your Aging Cat. She's also the behavior contributor for and can be reached via


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