Complete Care for Your Aging Cat Read online

  go moving the furniture, simple as that.”

  Aging Ears

  The normal feline ear can hear up to three times the range of sounds as

  that of people. But with age, the delicate structures within the ear begin to

  lose sensitivity to vibrations. This decline can be accelerated by damage

  from very loud noises. Chronic ear infections or parasite infestations, such

  as ear mites, may also damage the cat’s hearing.

  Age-related hearing loss, termed presbycusis, shows up in any animal if

  it lives long enough, says George Strain, DVM, a professor of

  neuroscience at Louisiana State University. “There’s a certain loss of

  nerve cel s with time in the body,” he says. Hearing loss can’t be reliably

  predicted, but once it starts, it continues to get worse with time.

  Cats can’t tel us they’re hard of hearing. “They compensate by paying

  more attention to their other senses,” says Dr. Strain. “They may become

  more visual y attentive, pay attention to vibration cues, air currents and

  things like that.” Many times owners don’t recognize the cat has lost

  hearing because it happens so gradual y, until suddenly they notice the cat

  startles when touched or stops running to greet the doorbel .

  Aging Taste

  Changes in flavor perception are thought to reflect those

  experienced by aging humans, says Nancy E. Rawson, Ph.D., of the Monel

  Chemical Senses Center, a nonprofit research institute in Philadelphia

  dedicated to research in the fields of taste, smel , chemical irritation and

  nutrition. “But as a carnivore, the feline’s senses of taste and smel are

  quite distinct from those of the human, and responses to age-associated

  changes may differ,” says Dr. Rawson.

  Cats aren’t able to detect carbohydrate sweeteners, but can taste

  and seem to prefer meaty flavors described by people as “sweet.”

  Detection of meaty, salty and sour flavors doesn’t seem to be affected by

  age. Bitter tastes are more sensitive to aging changes.

  Chemical irritations and “mouth feel” influence how wel the cat likes

  or dislikes a flavor. These can be influenced by changes in saliva content,

  for example, caused by dehydration that commonly develops in aged cats.

  Disease or medication can reduce or increase the sensitivity of the mouth

  and tongue, and alterations in taste (and smel ) can remain even after the

  disease is cured and the medicine is stopped. Dental disease creates a

  hypersensitive mouth, interferes with chewing ability, and produces

  unpleasant tastes and odors that prompt the cat to refuse certain foods.

  Warming foods increases the volatility of tastes and scents to make

  them more intense and appealing to the aging cat’s palate. Antioxidants

  hold promise for prevention of age-related scent and taste loss, says Dr.

  Rawson.

  Aging Nose

  Scent is very important for cats, but few studies have documented

  exactly what happens to its acuity in relation to age. Cats do lose smel ing

  sense the older they get, but nobody knows the amount due to changes of

  aging compared to lifetime damage, says Dr. Myers. “We’re just starting to

  get a handle on how much the vomeronasal organ contributes to the total

  scent picture for dogs and cats,” he says. The vomeronasal, or

  Jacobson’s, organ is in the roof of the mouth between the soft palate and

  nasal passages and is thought to be important in the detection of

  pheromones, chemicals primarily involved in prompting sexual behaviors.

  Snuffling foreign objects into the nose can cause damage. Upper

  respiratory infections as wel as endocrine diseases such as diabetes and

  hyperthyroidism also can damage the scenting apparatus. Age-related

  losses in the sense of smel result from changes in the anatomy—scent

  cel s aren’t replaced as often—and at the molecular level when existing

  nerve cel s and “messenger” molecules in the nose become less sensitive.

  Reduce salivation or altered nasal mucus composition also impact the way

  odor chemicals are dissolved and detected, says Dr. Rawson.

  “We did a study a number of years ago and published it in the annals of

  the New York Academy of Sciences that dealt with the lack of the sense of

  smel in the cat, and the influence of food intake,” says Dr. Myers. “A

  complete loss of vomeronasal as wel as olfactory nerve caused the cats

  not to eat at al . It seems as if the sense of smel gives them some sort of

  cue that it’s edible,” he says. “A favorite veterinarian trick is get one of the

  cheapest, nastiest, smel iest red tuna fish for cats when they stop eating.

  That does seem to work in a fairly substantial number to start them eating

  again.”

  Bones and Muscles

  By the time a cat becomes a senior citizen, her bones have begun to

  lose density and become weaker and more brittle. That means senior cats

  are more prone to fractures from fal s or leaps when they hit the ground.

  Cats at thirteen to fourteen general y heal more slowly from a fracture,

  says James L. Cook, DVM, an orthopedic surgeon at the University of

  Missouri. “That’s when we start to see a lot of the manifestations from

  arthritis with respect to the joints.” Slowed healing and bone loss likely are

  due to the body’s slowed capacity to regenerate bone cel s.

  “Orthopedical y, cats are real good healers,” says Dr. Cook.

  The cartilage cushioning the joints wears thinner and becomes more

  brittle over time, and the ligaments and tendons connecting the joints can

  stretch, become less flexible, and tear more easily. Because cats weigh

  much less than most dogs, the forces placed on bones and joints may not

  cause as much damage over a lifetime of wear as in dogs, says Dr. Cook.

  Obesity wil increase the risk for arthritis and strains and sprains.

  Cats hide symptoms better, and that makes diagnosis more difficult.

  “Cats are a little more stoic so the symptoms aren’t quite the same as in

  dogs,” says Bil Fortney, DVM, director of community practice at Kansas

  State University. Cats almost never limp or hold up a paw—they just hide

  under the bed or refuse to move. “They may not groom themselves very

  wel , they may be more irritable,” says Dr. Fortney.

  Muscles become less able to use nutrition efficiently. Cats tend to slow

  down as they age, and a reduction in exercise prompts not only a gradual

  atrophy and loss of muscle mass but also contributes to bone loss. Older

  cats that have less stamina and loss of muscle tone may not be able to

  “make it” to the litter box in time. “Muscle mass is an extremely important

  metabolic reservoir,” says Dan Carey, DVM, a veterinarian with the Iams

  Company. The body uses muscle as an energy source during il ness.

  Human studies show that il people with reduced muscle mass don’t

  survive as wel as those with a healthy muscle mass, says Dr. Carey.

  Digestion

  The digestive system includes the mouth, teeth, stomach, intestines,

  pancreas and liver. It processes nutrition and eliminates waste. One of the

  greatest digestion-related problems of aging cats is obesity, or “over-

  nutrition.” Older cats don�
��t exercise as much, and their metabolism slows

  down, so they gain more weight.

  However, because cats are true carnivores and use protein as a

  source for energy, if they don’t eat enough, they’l lose weight as they age.

  Cats may gain weight up to age ten, but then lose as they have less ability

  to digest protein and fat. In fact, weight loss particularly of lean muscle,

  tends to occur in cats at about two to two-and-a-half years prior to their

  death from age-related diseases, says Joe Wakshlag, DVM, assistant

  professor of clinical nutrition at Cornel University. He says studies in

  otherwise normal adult cats indicate that increasing dietary protein by 35

  percent (dry matter basis) enhanced lean muscle mass in these cats.

  Geriatric animals have a decreased thirst response, according to

  Alice Wolf, DVM, a professor of smal animal medicine and surgery at

  Texas A&M (now Emeritus/Adjunct Professor). That means they are more

  likely to become dehydrated when il , or even during routine boarding or

  hospitalization. Aged cats also exhibit a general decrease in GI motility

  and digestive enzymes and 20 to 30 percent of cats age 12 and older

  have significantly reduced digestive function, says Wil iam Fortney, DVM,

  an assistant professor at Kansas State University. The taste sensation is

  also reduced, which can lead to anorexia—refusal to eat.

  Probably the most common intestinal concern for aging cats is hairbal s.

  Hair swal owed during self-grooming is normal y passed out of the body

  with the feces. But because older cats may have more difficulty with motility

  —movement of waste through the bowels—hairbal s can complicate the

  problem and cause chronic vomiting or constipation.

  Aging Teeth

  Cats are prone to plaque and tartar formation on their teeth, just like

  people. They don’t indulge in recreational chewing the way dogs do, but

  may stil suffer from broken teeth especial y when the diseased tooth is

  weakened by resorbtive lesions, a type of feline cavity. Tartar and plaque

  buildup over time causes periodontal disease that can ultimately result in

  loss of teeth and also impact the health of the rest of the body.

  “Having periodontal disease is analogous to having an open wound,”

  says Bil Gengler, DVM, a veterinary dentist at the University of Wisconsin.

  Oftentimes the gum tissue is no longer attached to the tooth, and the root

  and bone are exposed. “When that happens, those clusters of bacteria

  travel through the bloodstream, and are filtered out at capil ary beds. This

  process is cal ed bacterial showering,” says Dr. Gengler. The bacteria are

  predominantly filtered out in the liver and the kidneys, and can damage

  these organs. It can also lead to heart disease because of the bacteria-

  laden blood passing over the valves of the heart.

  Aging Stomach and Intestines

  “The gastrointestinal tract in cats is relatively wel protected from the

  ravages of time,” says Dr. Colin Burrows, an internist and professor of

  medicine at the University of Florida. “In older cats, just as in older people,

  the ability to digest diminishes somewhat but it’s not frightful y significant.”

  Smal er but more frequent meals often help the cat’s body absorb more

  nutrition.

  “The only disease of note in the [older] cat that does not occur in the dog

  is idiopathic megacolon. This is the constipated kitty,” says Dr. Burrows.

  Megacolon is different than routine constipation, though, and develops as

  a result of motility problems. The intestines lose their ability to move waste

  out of the body.

  Also, the bacterial population in the cat’s intestinal tract changes as she

  ages, says Dr. Carey. “This isn’t as dramatic as in dogs, but in aging cats

  it does shift toward the undesirable bacteria. In large part they are

  diarrhea-type organisms that can invade the lining of the intestine,” he

  says.

  Chronic constipation or diarrhea are not specifical y “old cat” conditions.

  Obesity, lack of exercise, and hairbal s can contribute to constipation. The

  most common causes of colitis (inflammation of the colon) are stress,

  which can lead to bacterial overgrowth within the colon. Cats are creatures

  of habit and any change in their routine—adding a new pet, or working

  longer hours, for example—may cause stress-related disorders. Cats may

  also develop ulcers as a result of kidney disease.

  To compensate for changes in digestion, therapeutic diets may help.

  “Fat restriction may be beneficial because fat absorption and digestion

  depends on enzymes that are found in the very tip of the vil i that line the

  intestine, and this is the area that’s damaged first,” says Dr. Dottie

  LaFlamme, a veterinary researcher with Nestle Purina PetCare Company.

  “When you have damage to the intestine, fat malabsorption can occur, and

  that can lead to worsening of problems.”

  Aging Pancreas and Liver

  The pancreas, located near the liver, produces enzymes vital to

  digestion, and both the production of gastric and pancreatic secretions

  decrease as the cat ages. Similarly, the enzymes produced by the liver for

  metabolizing nutrients and detoxifying the body declines with age.

  Inflammation of the pancreas, cal ed pancreatitis, is a recently

  recognized disease of older cats, although the cause usual y is unknown.

  Stricken cats often develop a triaditis, says Cynthia R. Leveil e-Webster,

  DVM, an internist at Tufts University. That’s an inflammation in the

  pancreas, intestines and liver al at the same time.

  Overweight cats are especial y prone to a dangerous condition cal ed

  hepatic lipidosis, or fatty liver disease, in which fat is moved into the liver

  and interferes with its normal function. There are several other kinds of liver

  disease, but the symptoms are al pretty vague and quite similar. “Owners

  are not going to know that their animal has liver disease most of the time,”

  says Dr. Webster. “And the doctor won’t know until after a lot of test.”

  The liver continues to function wel , though, even when not at 100 percent

  capacity. When a cat needs medication, however, there may be trouble.

  “You need to be a little more cautious about medications with older

  animals,” says Dr. Webster. “Old pets are often on multiple medications,

  and drug interactions can affect how they are handled by the liver.” For

  instance, certain drugs can inhibit the normal production of liver enzymes.

  Therefore, if the liver is functioning at 70 percent and doing wel , but a drug

  reduces that to 35 percent, the body may suffer the consequences.

  Reduced efficiency compromises the old liver’s ability to metabolize

  medications properly, among other things.

  Endocrine System—Hormones

  The endocrine system consists of a huge network of glands and organs

  that produce hormones. The system includes the pituitary, thyroid,

  parathyroid, pancreas, adrenals, ovaries and testes.

  Hormones are a kind of “messenger” molecule secreted by endocrine

  glands that are carried by the bloodstream to various distant body sites,

  with instructions to alt
er that target tissue’s function—speed up or slow

  down digestion, for instance. They are made either of protein or a type of

  specialized fatty substance cal ed a steroid, and regulate body functions

  and coordinate interactions between the different body systems. An

  excess or deficient amount of a given hormone can cause disease.

  Older cats slow down in part because their metabolic rate goes down,

  says Dr. LaFlamme. Hormone imbalances become more common as the

  cat ages because of normal wear and tear on the organs, and also

  because age-related diseases like cancer often target the endocrine

  system. The most common old-cat endocrine disorders are

  hyperthyroidism and diabetes mel itus, discussed in Part 2 under their

  alphabetic listings.

  Heart and Lungs

  The cardiovascular system carries oxygen and nutrients throughout

  the body, and removes carbon dioxide and waste materials. The system

  includes the heart, blood, and lymphatic system.

  Old cats most often develop a heart disease cal ed cardiomyopathy,

  which affects the muscle of the organ. It becomes harder for the heart to

  work efficiently. Heart failure results when the damaged muscle is no

  longer able to move blood throughout the body properly. Thromboembolic

  disease can be a consequence, when blood clots form in the hind legs and

  cause rear-end weakness, paralysis and pain due to lack of oxygen.

  The respiratory system is composed of the nose, larynx, trachea,

  bronchial passages and lungs. This delivery system supplies the body with

  oxygen, and removes carbon dioxide.

  The airways are exposed to damage caused by inhaled al ergens,

  foreign bodies, viruses, bacteria and fungus and may result in a wide

  range of problems. Senior cats are much more prone to upper respiratory

  infections that can affect the lungs and/or nasal passages. For example, an

  accumulation of fluid within the chest wal , cal ed pleural effusion, surrounds

  the lungs and heart, and interferes with their ability to expand. Pleural

  effusion is most commonly a result of heart failure. Pulmonary edema, fluid

  within the lung itself, may develop as a result of cardiomyopathy,

  pneumonia, or cancer.

  Immunity

  The immune system is composed of the spleen, thymus, bone marrow,