Disease

Each year, many thousands of cats are brought to veterinary clinics throughout the U.S. showing the telltale signs of respiratory distress: labored breathing, chest constriction, wheezing and coughing. In the vast majority of cases, the animal will be diagnosed with asthma, a mechanical constriction of the airways, or bronchi, the narrow network of tubes that lead directly from the trachea to the lungs. The narrowing of the airways occurs when a cats immune system overreacts to the presence of an allergy-producing substance, such as cigarette smoke, dusty kitty litter or pollen and responds to the presence of the allergen by releasing stimulants that cause a swelling of the tissue (mucous membrane) lining the bronchi.

Chronic renal failure in a cat occurs when 75 percent or more of the animals healthy kidney tissue has been destroyed and replaced by scar tissue. As a consequence, the two kidneys, each of which contains many thousands of tiny filtering units (nephrons), are unable to carry out their chief function of removing metabolic waste from the blood that is pumped through them with each heartbeat. To compensate, most afflicted cats will drink increasing amounts of water in an effort to pass additional fluids through their kidneys. Unfortunately, this water will run quickly through the animals body; the cat will simply urinate more frequently. Meanwhile, the ultimately life-threatening metabolic waste will continue to circulate and to accumulate.

Your cat’s eyes, like yours, are delicate structures made up of various components —the cornea, pupil, iris, lens, retina and so forth — each of which plays a role in enabling the animal’s keen vision. While the feline eye is generally sturdy and resistant to injuries and disease, a wide variety of disorders, such as glaucoma and cataracts, can impair a cat’s vision and even, in some cases, lead to blindness. According to Thomas Kern, DVM, an associate professor of ophthalmology at Cornell University’s College of Veterinary Medicine, the most common of all feline eye disorders is conjunctivitis, an inflammation of the thin mucous membrane (conjunctiva) that lines the inner surface of the eyelids and coats the outer surface of the eyeball.

Veterinarians generally recommend that all cats undergo a thorough physical examination at least once a year until they have reached seven or eight years of age, and twice annually thereafter as they progress into their senior years. Such a multifaceted exam will include a complete blood count (CBC), a procedure that, thanks to a variety of sophisticated laboratory techniques and equipment, can reveal or at least suggest the presence of many feline health disorders. (See related article in the June 2007 issue of CatWatch.)

If you happen to be sitting in on your cats routine physical exam, youre likely at some point to observe the veterinarian carefully studying the animals face, gently stroking its nose, and fondling its ears. This is not merely a show of affection. Rather, the veterinarian is searching for tiny, scabby sores on the cats skin that could indicate the presence of squamous cell carcinoma (SCC) - a skin cancer that, if caught in its early stage, will most likely be harmless and easily treated. If the skin eruptions go unnoticed, however, the cancer can progress, spread to other parts of the body, and ultimately prove fatal.

Whether your cat is wide awake or sleeping soundly, its immune system remains on full alert, protecting the animal from assault by the viruses, bacteria and other foreign invaders - called antigens - in its environment. And in the vast majority of cats, the immune system will continue to function effectively - without letup - from the day an animal is born until the day it dies.

Your cats digestive system, a complex assemblage of several interdependent components, plays a crucial and multifaceted role in maintaining the animals good health. An essentially tubular arrangement leading from its mouth to its anus, the system - when functioning properly - breaks down the food that the animal has eaten into nutrient-rich particles and facilitates their absorption while also serving as a barrier against disease-producing organisms that the cat may have ingested.

Your cats kidneys, two relatively small organs located behind its rib cage - one on each side of its spine - play a central role in almost all of its bodily processes. They help to control the blood pressure and regulate the amount and chemical consistency of fluid in the bloodstream. They produce a variety of vitally needed hormones and enzymes, and they contribute to the production of red blood cells.

Fever, lethargy, loss of appetite and evidence of painful stiffness in the muscles and joints are clinical signs of many ailments that can afflict your cat at any time of year. Some feline disorders, however, are more prevalent during warm weather, when higher temperatures stimulate the activity of disease-causing organisms and the parasites that can transmit them to your cat.

The eye is an amazing, delicate organ. Cells within the eye normally produce a clear fluid (aqueous humor) that serves to nourish and maintain the shape of the eye. When the balance between the production and the drainage of fluid is upset, glaucoma can result. Decreased drainage of fluid causes increased pressure (and pain) within the eye, often resulting in damage to the optic nerve and, consequently, loss of vision.

Thanks to advances in veterinary medicine, many of the cancers to which cats are susceptible are now controllable, sometimes curable, and even (in the case of mammary cancer, for example) potentially preventable. This does not always hold true, however, for osteosarcoma, a highly destructive feline bone cancer for which there is no known cure unless it is detected early.

Toxoplasmosis is a fairly common zoonosis (a disease that can be shared between humans and animals); 30 to 40 percent of adult humans, and roughly the same percentage of cats, have antibodies that indicate prior exposure to the organism that causes the disease. Nevertheless, its particulars are still unfamiliar to many people. The disease poses a threat primarily to fetuses and to immunosuppressed patients, but an understanding of the organisms life cycle, how transmission occurs and can be avoided, and the signs of infection can greatly reduce the risk of serious disease.