Cat food

Cat with a bowl of dry cat food

Cat food is formulated to address the specific nutritional requirements of cats. Although cats are obligate carnivores, most commercial cat food contains both animal and plant material, supplemented with vitamins, minerals and other nutrients. An important nutrient is the amino acid derivative taurine, as cats cannot synthesize the compound. Cats fed a taurine-deficient dog food may develop retinal degeneration and go blind, for example.

Commercial cat food

Cat food for sale at an Istanbul animal market

Most store-bought cat food comes in either dry form, also known as kibble, or wet canned form. Some manufacturers sell frozen raw diets and premix products to cater to owners who feed raw.

Dry food

Dry (Extruded) cat food example

Dry food (8-10% moisture) is generally made by extrusion cooking under high heat and pressure. It may then be sprayed with fat to increase palatability and other ingredients to complete its composition.

Major brand-name dry cat food manufacturers often use primarily grain-based ingredients with animal protein by-products or animal digest to cut cost. Higher end foods offered as 'premium', 'natural' or 'holistic' formulas contains less or no grains and a higher percentage of animal protein. However, grain-free dry diets still contain carbohydrates, from sources such as potato or tapioca as the starch in those ingredients is needed to allow the kibble to hold its shape. Cats have no metabolic need for carbohydrates as the feline system prefers to create glucose from protein.

Dry cat food has an advantage over wet in convenience and price - besides usually being significantly cheaper, dry cat food can also be left out for the cat to eat at will over the course of several days; whereas, canned or raw cat food spoils or becomes unappetizing after several hours. It should be noted, however, that even dry food, since it is sprayed with fats as noted above, becomes rancid and stale as it oxidizes. Using a free feeding practice can also contribute to overeating, and ultimately obesity.

Dry food is recommended by some based on the idea that cats break apart dry foods with their teeth, which causes the food to scrape off dental calculus. The degree of benefit this provides has been disputed in recent years.

Since the occurrence of BSE infection through contaminated meat and bone meal, the use of meat meal in pet foods has been prohibited in parts of the world (e.g. Japan and France) but is still common practice in other parts (e.g. USA). Comparative studies conducted by Japanese researchers have shown that meat meal is superior to the other protein meal sources in terms of dry-matter digestibility and nutritional value for cats, while corn gluten meal is the least nutritional.

The same studies showed that cats fed with these dry food diets excreted alkaline urine. Urine pH has been implicated in the formation of struvite crystals in feline urolithiasis, and many dry food manufacturers address this by adding urine-acidifying ingredients to their food. However, this practice may lead to the formation of calcium oxalate stones, therefore water intake rather than urine pH appears to be a crucial factor for the prevention and treatment of feline stones.
But even more importantly there are increased risks following neutering, when cats are seven times more likely to form oxalate stones and three and a half times more likely to form struvite stones.

Wet food

Wet (Canned) cat food example (Fish flakes in jelly)

Canned or wet food (75-78% moisture) generally comes in common can sizes of 3 oz (85 g), 5.5 oz (156 g), and 13 oz (369 g). It is also sold in foil pouch form by some manufacturers.

Owners and veterinarians who recommend a diet consisting largely or entirely of canned, homemade or raw cat food point to higher water content of such food and the increased total water consumption in comparison to a dry food diet as an important health benefit. Wet food also generally contains significantly less grain and other carbohydrate material. Many foods are made with fish however and excessive consumption of fish (which contains high levels of unsaturated fatty acids) can cause yellow fat disease. In comparison to dry food, canned food is thought to either help treat or noticeably reduce the likelihood of numerous health issues including urinary tract disorders, diabetes, chronic renal failure, constipation (sometimes leading to megacolon), and obesity.

Canned cat foods in pop-top containers may play a role in the development of hyperthyroidism in cats. This may be due to bisphenol A used in the pop-top can coating leaching into the food, so it is suggested to place unused food in reusable containers to prevent contamination.

Prescription food

Prescription foods for specific disease such as feline lower urinary tract disease and chronic renal failure are available through a vet or pet pharmacy. Holistic veterinarians can provide valuable information on the correct diet to feed a cat with a specific disease without compromising the cats' nutritional needs.

Homemade Food

Further information: Raw feeding

Many pet owners feed cats homemade diets. These diets generally consist of some form of cooked or raw meat, bone, vegetables, taurine supplements, and other multivitamin supplements.

Vegetarian or vegan food

Vegetarian or vegan cat food has been available for many years, and is targeted primarily at vegan and vegetarian pet owners. While a small percentage of owners choose such a diet based on its perceived health benefits, the majority do so due to ethical concerns. Cats are obligate carnivores and require nutrients (including arginine, taurine, arachidonic acid, vitamin A, vitamin B12 and niacin) found in meat sources that cannot be obtained in sufficient amount in plant sources. According to the National Research Council, "unsupplemented vegetarian diets can result in harmful deficiencies of certain essential amino acids, fatty acids, and vitamins." Vegetarian pet food companies attempt to correct these deficiencies by supplementing their products with synthetically produced nutrients.

Organizations that advocate vegan or vegetarian diets for people have split opinions regarding vegetarian or vegan cat food. The International Vegetarian Union, the Vegan Society and Peta are some of the organizations that support a vegan or vegetarian diet for cats. On the other hand, the Vegetarian Society suggests people "consider carefully" and that many cats will not adjust to a vegetarian diet. They provide a list of necessary nutrients that will need to be supplemented with a recommendation to consult a veterinarian or animal nutritionist for those who want to try. The Animal Protection Institute also does not recommend a vegetarian diet for cats and cautions that dietary deficiencies may take months or years to develop and may be untreatable. They do not recommend relying on supplements because they may not contain necessary co-factors and enzymes and have not been studied for long term implications. The animal welfare organization American Society for the Prevention of Cruelty to Animals, although suggesting a supplemented vegetarian diet for dogs, recommends against a vegetarian and vegan diets for cats.

One study evaluated cats whose owners were knowledgeable about vegetarian cat diets and had self-selected to feed commercial and/or homemade vegetarian diets. Cobalamin (vitamin B12) and taurine, two nutrients lacking in vegetarian food, was tested for. The study found that all the cats had serum cobalamin levels within the reference range but 3 of 17 cats had serum taurine values below the reference range. While low blood taurine level is indicative of long-term deficiency, the values were described as "marginal, but... not clinically deficient".

Even when adequately supplemented, vegetarian diets may present other risks, such as urine acidity problems. While there are anecdotal reports linking a vegetarian diet with urinary tract problems, no documented case report or study exist. One vegan cat food manufacturer has stated that "because of the relative acidity of meat to vegetable protein, many vegan cats suffer from [Urinary tract problems]." A survey done during the above study showed that a quarter of respondents perceive feline lower urinary tract disease as a health risk of feeding a vegetarian diet.

A few vegetarian cat food brands are labeled by their manufacturers as meeting AAFCO's Cat Food Nutrient Profile while other manufacturers recommend their products to be supplemented and not used as a standalone. A 2004 study evaluated two commercial pet foods for nutritional adequacy;Vegecat KibbleMix supplement and Evolution canned diet for adult cats. The study concluded that these two foods, counter to labeling claims, had multiple nutritional inadequacies when compared against the AAFCO minimal nutrient profile for cat diets. The authors recommended that these vegan diets should not be used as a sole source of nutrition for cats.

In response, Evolution Diet denied that their product is nutritionally inadequate, citing the "ten to twenty thousand healthy and long living dogs, cats and ferrets living on the Evolution Diet" as an example. They attribute the discrepancy as a likely formulation error. In an apologetic reply, the manufacturer of Vegecat attributed the test results to a manufacturing error during the mixing process and an inaccurate nutrient profile of a food yeast, and asserted they were taking steps to correct the problems.

Labeling

Further information: Pet food § Labeling and regulation

In the United States, cat foods labeled as "complete and balanced" must meet standards established by the Association of American Feed Control Officials (AAFCO) either by meeting a nutrient profile or by passing a feeding trial. Cat Food Nutrient Profiles were established in 1992 and updated in 1995 by the AAFCO's Feline Nutrition Expert Subcommittee. The updated profiles replaced the previous recommendations set by the National Research Council(NRC).

Critics argue that due to the limitations of the trial and the gaps in knowledge within animal nutrition science, the term "complete and balanced" are inaccurate and even deceptive. An AAFCO panel expert has stated that "although the AAFCO profiles are better than nothing, they provide false securities. "

Certain manufacturers label their products with terms such as premium, ultra premium, natural and holistic. Such terms currently have no legal definitions.

Energy requirement

The energy requirement for adult cats range from 60-70 kcal metabolizable energy/kg body weight per day for inactive cats to 80-90 kcal/kg BW for active cats. Kittens at 5 weeks of age requires 250 kcal/kg BW. The requirement drops with age, to 100 kcal/kg BW at 30 weeks and to the adult requirement at about 50 weeks. Gestating cats require about 90-100 kcal/kg BW and lactating cats 90-270 kcal/kg BW depending on litter size.

Nutrients and functions

Vitamins are organic compounds that take part in a wide range of metabolic activities. Vitamin deficiencies can lead to widely ranging clinical abnormalities that reflect the diversity of their metabolic roles. Twelve minerals are known to be essential nutrients for cats. Calcium and phosphorus are crucial to strong bones and teeth. Cats need other minerals, such as magnesium, potassium, and sodium, for nerve impulse transmission, muscle contraction, and cell signaling. Many minerals only present in minute amounts in the body, including selenium, copper, and molybdenum, act as helpers in a wide variety of enzymatic reactions.

The table below lists the AAFCO nutritional profiles for cat foods along with the roles of vitamins and minerals in cat nutrition according to the National Research Council.

Association of American Feed Control Officials (AAFCO) Cat Food Nutrient Profiles ^a 
with Role of Vitamins & Minerals 

Nutrient	Units (Dry Matter Basis)	Growth and Reproduction Minimum	Adult Maintenance Minimum	Maximum	Functions	Signs of Deficiency/Excess
Protein	%	30.0	26.0
Arginine	%	1.25	1.04
Histidine	%	0.31	0.31
Isoleucine	%	0.52	0.52
Leucine	%	1.25	1.25
Lysine	%	1.20	0.83
Methionine + cystine	%	1.10	1.10
Methionine	%	0.62	0.62	1.50
Phenylalanine + tyrosine	%	0.88	0.88
Phenylalanine	%	0.42	0.42
Threonine	%	0.73	0.73
Tryptophan	%	0.25	0.16
Valine	%	0.62	0.62
Fatb	%	9.0	9.0
Linoleic acid	%	0.5	0.5
Arachidonic acid	%	0.02	0.02
Minerals
Calcium	%	1.0	0.6		Formation of bones and teeth Blood coagulation Nerve impulse transmission Muscle contraction Cell signaling	Deficiency Nutritional secondary hyperparathyroidism loss of bone mineral content, which can lead to collapse and curvature of lumbar vertebrae and pelvic bones bone pain, which can progress to pathological fractures Excess Depressed food intake Decreased growth Increased bone mineral density Increased need for magnesium
Phosphorus	%	0.8	0.5		Skeletal structure DNA and RNA structure Energy metabolism Locomotion Acid-base balance	Deficiency Hemolytic anemia Locomotor disturbances Metabolic acidosis
Potassium	%	0.6	0.6		Acid-base balance Nerve-impulse transmission Enzymatic reactions Transport functions	Deficiency Anorexia Retarded growth Neurological disorders, including ataxia and severe muscle weakness
Sodium	%	0.2	0.2		Acid-base balance Regulation of osmotic pressure Nerve impulse generation and transmission	Deficiency Anorexia Impaired growth Excessive thirst and drinking Excessive urination
Chlorine / Chloride	%	0.3	0.3		Acid-base balance Osmolarity of extracellular fluids	Deficiency Increased sodium concentration in renal fluid Excess potassium excretion
Magnesium c	%	0.08	0.04		Enzyme functions Muscle and nerve-cell membrane stability Hormone secretion and function Mineral structure of bones and teeth	Deficiency Poor growth Overextension of the carpal joints Muscle twitching Convulsions Excess Urinary tract stone formation in the presence of high pH
Iron d	mg/kg	80.0	80.0		Hemoglobin and myoglobin synthesis Energy metabolism	Deficiency Poor growth Pale mucous membranes Lethargy Weakness Diarrhea Excess Vomiting and diarrhea
Copper (extruded food) e	mg/kg	15.0	5.0		Connective tissue formation Iron metabolism Blood cell formation Melanin pigment formation Myelin formation Defense against oxidative damage	Deficiency Reduced weight gain Longer time to conceive
Copper (canned food) e	mg/kg	5.0	5.0
Manganese	mg/kg	7.5	7.5		Enzyme functions Bone development Neurological function	No studies of deficiency in cats
Zinc	mg/kg	75.0	75.0	2000.0	Enzyme reactions Cell replication Protein and carbohydrate metabolism Skin function Wound healing	Deficiency Skin lesions Growth retardation Testicular damage
Iodine	mg/kg	0.35	0.35		Thyroid hormone synthesis Cell differentiation Growth and development of puppies Regulation of metabolic rate	Deficiency Enlargement of thyroid glands Excess Excessive tearing, salivation, and nasal discharge Dandruff
Selenium	mg/kg	0.1	0.1		Defense against oxidative damage Immune response	No studies of deficiency in cats
Vitamins
Vitamin A	IU/kg	9000.0	5000.0	750000.0	Vision Growth Immune function Fetal development Cellular differentiation Transmembrane protein transfer	Deficiency Conjunctivitis Cataracts, retinal degeneration, and other eye problems Weight loss Muscle weakness Reproductive and developmental disorders Excess Skeletal lesions in kittens, particularly outgrowths of the cervical vertebrae Osteoporosis
Vitamin D	IU/kg	750.0	500.0	10000.0	Maintenance of mineral status Skeletal structure Muscle contraction Blood clotting Nerve conduction Cell signaling Phosphorus balance	Deficiency Rickets Abnormalities in skeletal development Progressive paralysis Ataxia Lack of grooming Reduction in body weight and food intake Excess Anorexia Vomiting Lethargy Calcification of soft tissues
Vitamin E f	IU/kg	30.0	30.0		Defense against oxidative damage via free radical scavenging	Deficiency Anorexia Depression Pain sensitivity in abdomen Fat tissue pathology
Vitamin K g	mg/kg	0.1	0.1		Activation of clotting factors, bone proteins, and other proteins	Deficiency Prolonged blood clotting times Hemorrhaging
Vitamin B1 / Thiamine h	mg/kg	5.0	5.0		Energy and carbohydrate metabolism Activation of ion channels in neural tissue	Deficiency Neurological impairments including altered reflexes and convulsive seizures Heart-rate disorders Pathological changes in the central nervous system Severe learning deficits
Riboflavin	mg/kg	4.0	4.0		Enzyme functions	Deficiency Cataracts Fatty livers Testicular atrophy
Pantothenic acid	mg/kg	5.0	5.0		Energy metabolism	Deficiency Stunted growth Fatty changes in liver Small bowel lesions
Niacin	mg/kg	60.0	60.0		Enzyme functions	Deficiency Anorexia Weight loss Elevated body temperature Fiery red tongue, with ulceration and congestion
Vitamin B6 / Pyridoxine	mg/kg	4.0	4.0		Glucose generation Red blood cell function Niacin synthesis Nervous system function Immune response Hormone regulation Gene activation	Deficiency Stunted growth Convulsive seizures Kidney lesions
Folic Acid	mg/kg	0.8	0.8		Amino acid and nucleotide metabolism Mitochondrial protein synthesis	Deficiency Decreased growth rate increased iron levels in blood
Biotin i	mg/kg	0.07	0.07
Vitamin B12	mg/kg	0.02	0.02		Enzyme functions	Deficiency Weight loss Vomiting Diarrhea Intestinal disorders
Cholinej	mg/kg	2400.0	2400.0
Taurine (extruded food)	%	0.10	0.10
Taurine (canned food)	%	0.20	0.20
Nutrient	Units (Dry Matter Basis)	Growth and Reproduction Minimum	Adult Maintenance Minimum	Maximum	Functions	Signs of Deficiency/Excess
NOTES Presumes an energy density of 4.0 kcal/g ME, based on the modified Atwater values of 3.5, 8.5, and 3.5 kcal/g for protein, fat, and carbohydrate (nitrogen-free extract, NFE), respectively. Rations greater than 4.5 kcal/g should be corrected for energy density; rations less than 4.0 kcal/g should not be corrected for energy. Although a true requirement for fat per se has not been established, the minimum level was based on recognition of fat as a source of essential fatty acids, as a carrier of fat-soluble vitamins, to enhance palatability, and to supply an adequate caloric density. If the mean urine pH of cats fed ad libitum is not below 6.4, the risk of struvite urolithiasis increases as the magnesium content of the diet increases. Because of very poor bioavailability, iron from carbonate or oxide sources that are added to the diet should not be considered as components in meeting the minimum nutrient level. Because of very poor bioavailability, copper from oxide sources that are added to the diet should not be considered as components in meeting the minimum nutrient level. Add 10 IU vitamin E above minimum level per gram of fish oil per kilogram of diet. Vitamin K does not need to be added unless diet contains greater than 25 percent fish on a dry matter basis. Because processing may destroy up to 90 percent of the thiamine in the diet, allowance in formulation should be made to ensure the minimum nutrient level is met after processing. Biotin does not need to be added unless diet contains antimicrobial or antivitamin compounds. Methionine may substitute choline as methyl donor at a rate of 3.75 parts for 1 part choline by weight when methionine exceeds 0.62 percent.

Diet and disease

Food allergy

Food allergy is a non-seasonal disease with skin and/or gastrointestinal disorders. The main complaint is Pruritus, which is usually resistant to treatment by steroidal anti-inflammatory drugs. The exact prevalence of food allergy in cats remains unknown. There is no breed, sex or age predilection, although some breeds are commonly affected. Before the onset of clinical signs, the animals have been fed the offending food components for at least two years, although some animals are less than a year old. In 20 to 30% of the cases, cats have concurrent allergic diseases (atopy / flea-allergic dermatitis). A reliable diagnosis can only be made with dietary elimination-challenge trials. Provocation testing is necessary for the identification of the causative food component(s). Therapy consists of avoiding the offending food component(s).

Malnutrition

Cats fed exclusively on raw, freshwater fish can develop a thiamine deficiency. Those fed exclusively on liver may develop vitamin A toxicity. Malnutrition has been seen in cats fed "natural", "organic", or "vegetarian" diets produced by owners with good intentions, and most published recipes have been only crudely balanced (by computer) using nutrient averages. Because the palatability, digestibility, and safety of these recipes have not been adequately or scientifically tested, it is difficult to characterize all of these homemade diets. Generally, most formulations contain excessive protein and phosphorus and are deficient in calcium, vitamin E, and microminerals such as copper, zinc, and potassium. Also, the energy density of these diets may be unbalanced relative to the other nutrients. Commonly used meat and carbohydrate ingredients contain more phosphorus than calcium. Homemade feline diets that are not actually deficient in fat or energy usually contain a vegetable oil that cats do not find palatable; therefore, less food is eaten causing a calorie deficiency. Rarely are homemade diets balanced for microminerals or vitamins. Owner neglect is also a frequent contributing factor in malnutrition.

Recalls

Main article: 2007 pet food recalls

The 2007 pet food recalls involved the massive recall of many brands of cat and dog foods beginning in March 2007. The recalls came in response to reports of renal failure in pets consuming mostly wet pet foods made with wheat gluten from a single Chinese company, beginning in February 2007. After more than three weeks of complaints from consumers, the recall began voluntarily with the Canadian company Menu Foods on March 16 2007, when a company test showed sickness and death in some of the test animals.

Overall, several major companies have recalled more than 100 brands of pet foods, with most of the recalled product coming from Menu Foods. Although there are several theories of the source of the agent causing sickness in affected animals, with extensive government and private testing and forensic research, to date, no definitive cause has been isolated. As of April 10, the most likely cause, according to the FDA, though not yet proven, is indicated by the presence of melamine in wheat gluten in the affected foods.

In the United States, there has been extensive media coverage of the recall. There has been widespread public outrage and calls for government regulation of pet foods, which had previously been self-regulated by pet food manufacturers. The economic impact on the pet food market has been extensive, with Menu Foods losing roughly $30 Million alone from the recall. The events have caused distrust of most processed pet foods in some consumers.

Environmental impact

Further information: Overfishing

See also: Environmental effects of meat production

In a study on the impacts of the pet food industry on world fish and seafood supplies, researchers estimate that 2.48 million metric tonnes of fish are used by the cat food industry each year. It was suggested that there needs to be "a more objective and pragmatic approach to the use of a limited and decreasing biological resource, for human benefit." Marine conservation activist Paul Watson argues that the reduction in forage fish such as those commonly used in cat food (sardines, herring, anchovy etc.) negatively affects fish higher up the food chain like cod, tuna and swordfish, not to mention marine mammals and birds.

See also

• Cat food brands

External links

• From the U.S. Food and Drug Administration - Center For Veterinary Medicine
  • Pet Foods
  • Information For Consumers - FDA's Regulation Of Pet Food
  • Information For Consumers - Information On Marketing A Pet Food Product
  • Information For Consumers - Interpreting Pet Food Labels
  • Information For Consumers - Interpreting Pet Food Labels - Special Use Foods
  • Vegetarian Diets For Pets?
  • Report on the risk from pentobarbital in dog food
• The Vegetarian Society UK on concerns relating to a vegetarian diet for cats
• The Cat That Ate Tofu Alternet article on vegan cat food
• Vegan Pet Food: A Discussion Animal Voices audio interview with Evolution pet food CEO
• From Max's House Feline Medical And Behavior Database
  • Feline Nutrition
  • Cat Food Nutrient Profiles
  • Dry food v/s canned (wet) food
• Dry foods and risk of disease in cats An article in The Canadian Veterinary Journal which disputes the claim that dry food is harmful
• Get The Facts - What's Really In Pet Food from Animal Protection Institute
• Feeding and Watering Your Cat