Cats require about 1 ounce (30 ml) of water per pound of body weight daily. They obtain this water in the food they eat and the liquids they drink. Water is also a by-product of metabolism; fat metabolism, in particular, is of great importance. The importance of foods in supplying the water requirements of cats is so great, in fact, that a cat on a moist food diet (which contains about 75% water) can easily be thought not to drink at all. Cats on other diets, however, do drink frequently, and the actual amount of liquid a cat must drink daily is influenced by many factors in addition to diet, among them exercise, environmental temperature, and the presence of fever, vomiting, or diarrhea. Lactation also increases the required water intake. So the best solution to the problem of water intake is to be sure that your cat has access to clean water at all times. (Milk may be provided as an additional water source if it does not cause diarrhea.) Do not give your cat water considered unfit for human consumption, and, if for some reason you are unable to give your cat free water access, be sure to offer water at least three times a day. A cat can go without food for days and lose 30% to 40% of his or her normal body weight without dying, but a water loss of 10% to 15% can be fatal. When cats stop eating (as they do frequently when sick) they must drink more water to make up for the decreased intake of food and in the amount provided by metabolism and for possible increases in need. To find out about providing water for your cat during illness.
Although the required levels of all the essential vitamins that should be included in cats’ diets have not been firmly established, many important facts about vitamins in the cat’s diet are known and should be heeded when selecting a diet for your pet. The table shows the currently recommended amounts of vitamins that should be fully available to a cat from his or her food. As with other nutrients, these levels will generally be lower than those actually present in commercial foods, since manufacturers must include higher levels when the food is formulated and first mixed to make up for nutrients that are not fully bioavailable from foods and losses caused by processing or storage.
Cats cannot convert beta carotene (found in green vegetables) to vitamin A as can dogs and people, so you must be sure that other sources of fully formed vitamin A (found in animal tissues) are provided in the diet to prevent a deficiency that can result in skin, eye, and reproductive changes. On the other hand, too much vitamin A in the diet can result in proliferative gingivitis, skeletal deformities, and crippling. In order to prevent vitamin A deficiency or excess, use a complete commercial cat food with vitamin A added as a basis for feeding and use liver, which is high in vitamin A, only as a supplement to your cat’s diet, not as a major part of it. Feed an average-sized adult cat no more than 1 ounce (30 g) of beef liver twice weekly. If necessary, balanced vitamin-mineral preparations may also be used as dietary supplements, but avoid giving unbalanced supplements such as cod liver oil to cats, since 1 teaspoonful can contain more than 5000 IU vitamin A. Use only balanced vitamin-mineral supplements recommended by your veterinarian and follow directions for their use carefully.
It is doubtful whether under normal feeding conditions vitamin E deficiency or excess will occur. There have been, however, many cases of
vitamin E deficiency in cats because the need for vitamin E is significantly influenced by diet composition. Cases of vitamin E deficiency have resulted from an abnormal feeding practice considered normal by poorly informed owners: the feeding of excessive quantities of red meat tuna. It has also occasionally followed the feeding of other fish diets, fish oils (e.g., cod liver oil), or large quantities of liver. Vitamin E deficiency results in oxidation of body fat and a generalized inflammation called pansteatitis (steatitis). Its signs include lack of appetite, fever, and pain accompanied by reluctance to move. It can eventually end in death. Vitamin E deficiency should be diagnosed and treated by a veterinarian, but, more important, you can prevent its occurrence. Use a complete commercial cat food as your cat’s basic diet and avoid frequent feeding of red meat tuna. Any tuna fed should be clearly marked—supplemented with vitamin E. Do not use fish oils (e.g., cod liver oil) as dietary supplements and feed liver only as previously recommended.
B VITAMINS (THIAMINE, RIBOFLAVIN, PYRIDOXINE, PANTOTHENIC ACID, NIACIN, B12)
Cats have relatively high requirements for B vitamins in their diets. Foods for cats must contain at least twice the amounts of many B vitamins found in diets adequate for dogs—another good reason not to feed cats dog food. Several B vitamins are destroyed by heating, a process used in making commercial cat foods, so all good processed foods must be supplemented with B vitamins. One heat-sensitive B vitamin, thiamine, is also destroyed by enzymes found in certain raw fish and in raw soybeans. Deficiency manifested by lack of appetite and neurologic disorders including seizures followed by weakness and death may develop in cats fed inadequately cooked fish or soy-based food and/or cooked products inadequately supplemented with thiamine. Several B vitamins are synthesized by bacteria in the intestines of healthy cats. Intestinal problems, e.g., diarrhea, can eliminate this source, and antibiotics may also interfere with it. Vitamin supplementation is often necessary during prolonged illnesses involving the intestine or during
prolonged antibiotic treatment.
Although few studies have been done that establish the mineral requirements of cats, it seems unlikely that a cat who eats a diet well balanced in other respects would become deficient in minerals. Unsuspecting cat owners can more easily provide improper rather than inadequate mineral supplies for their pets, since the relationship among the various minerals in the diet is as important as deficiency or excess. A good example of this problem is the interrelationship among the minerals calcium and phosphorus and vitamin D. These relationships are often upset by oversupplementation and/or by catering to a cat’s food preferences instead of his or her needs.
CALCIUM, PHOSPHORUS, VITAMIN D
Calcium and phosphorus should be present in the diet of cats in a ratio of about 1 to 1. If an adequate amount of each of these minerals is present but the ratio is incorrect, abnormal mineralization of bone occurs in the growing kitten and in the adult cat as well. If adequate amounts of calcium and phosphorus in the proper ratio are provided but without sufficient vitamin D, abnormalities of bone result again. Insufficient levels of vitamin D interfere with calcium absorption in the intestine. Excessive amounts of vitamin D in the presence of adequate levels of calcium and phosphorus may result in excessive mineralization of bone, abnormal teeth, and calcification of the soft tissues of the body. The delicacy of these relationships is remarkable. Unthinking or uninformed owners most often distort the calciumphosphorus balance of their cat’s diet by feeding a diet consisting almost exclusively of muscle meat or organ meats such as liver, heart, or kidney. All of these meats contain phosphorus but are devoid of calcium, which results in a calcium-phosphorus ratio of 1 to 15 or greater. Prolonged feeding of such a diet results in severe demineralization of bones, pain,
and sometimes fractures or paralysis, a condition called nutritional secondary hyperparathyroidism. An adult cat may exist on such a diet for years without showing signs of disease, but the body changes are occurring nevertheless. A cat’s requirement for vitamin D is low, so that health problems relating to this nutrient are best avoided by preventing oversupplementation. Remember that the wild ancestors and living relatives of the domestic cat relied on a variety of foods. Follow the dietary recommendations set out previously and on the following pages and/or follow the advice of a knowledgeable veterinarian to prevent nutritioninduced disease in your cat.