Complete Care for Your Aging Cat - Amy Shojai [22]
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, called pancreatitis, is a recently recognized disease of older cats, although the cause usually is unknown. Stricken cats often develop a triaditis, says Cynthia R. Leveille-Webster, DVM, an internist at Tufts University. That’s an inflammation in the pancreas, intestines and liver all at the same time.
Overweight cats are especially prone to a dangerous condition called 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 all 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 well, 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 well, 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 alter 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 called 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 mellitus, 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 called 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 allergens, 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 wall, called pleural effusion, surrounds the lungs and heart, and interferes