View Single Post
Old July 14th, 2011, 03:03 AM
growler~GateKeeper's Avatar
growler~GateKeeper growler~GateKeeper is offline
Join Date: May 2007
Posts: 17,390

Dry Food vs Canned Food. Which is really better?

A carnivorous diet is comprised of primarily protein and fat from animal tissue. They have teeth designed to tear flesh and a short and simple gastrointestinal tract, one suited for digestion and absorption of a concentrated, highly digestible diet. Dry foods typically contain 35-40% carbohydrate. Carbohydrates are nearly absent in the cat's natural diet. The cat obtains small amounts of carbohydrate through the stomach and intestines of her prey. Commercial dry foods, however, may contain as much as 45% - 50% carbohydrates. Since the cat metabolizes primarily fat and protein for energy, most of the excess carbohydrate is stored in the body as glycogen and fat. The primary adverse effect of excess carbohydrate is obesity. The effects of obesity are heart disease because of the increased workload on the heart; orthopedic problems are increased because of increased physical stress on the frame, leading to arthritis and early debilitation; diabetes mellitus, a condition in which the pancreas doesn't produce the amount of insulin that it should to help metabolize blood sugar, is one of the most common problems in obese cats; several liver disorders occur more frequently in overweight cats. Surprisingly, the deadliest one, hepatic lipidosis, happens when the cat stops eating. Changes in the operation of the liver cause fat to be deposited there, which eventually can shut down the liver altogether.

Not all protein sources are of equal value to the carnivore, and the quantity of protein in a commercial dry cat food often says nothing about its quality. Before domestication, cats hunted their prey and consumed a diet very high in meat protein, low to moderate in fat, and very low in carbohydrates. This diet provided both the proper quantity and quality of protein for the carnivore's unique digestive system.
.... Thus, a carnivore's optimum diet must be concentrated, highly digestible, and low in residue because its body is designed to digest primarily protein. If an excess of carbohydrates is included in the diet, much of what the carnivore eats is only partially digested by the time it reaches the large intestine for fecal formation, overloading the digestive and excretory systems. ...

Protein digestibility in pet foods is about 80 percent for dry foods, 85 percent for semimoist and canned foods containing large amounts of cereal grains, and 90 percent for canned diets with meat as the primary protein source. Digestibility is influenced both by the source of the protein and by how it is processed. Protein in cat foods comes from both animal and plant sources. Animal protein is generally more expensive and often of higher quality than plant protein. The composition of canned foods allows the use of protein and fat sources of higher biological value than can be used in dry food.

The cat's natural diet, live prey, contains between 65%-75% water. The cat, having evolved on the plains of Africa, has adapted to obtain her water requirements almost entirely on the moisture content in her prey. Cats can live for long periods without drinking water when receiving food containing 67-73% water but become dehydrated when the water content of the food is 63% or less. The water content of the commercial foods commonly fed to cats varies from 8% in dry foods to over 75% in canned foods; thus the amount of drinking water required is affected substantially by the water content of the food. {All dry-fed-only cats become chronically dehydrated because they cannot drink enough water for their bodies to restore what they loose, re-hydrate & maintain it adequately}

In addition to canned food ensuring adequate hydration, a high water turnover helps eliminate crystallogenic substances before they grow to sufficient size to interfere with normal urinary function. This is a very important consideration for male cats. Cats that cannot urinate for more than 24 hours due to urinary tract obstruction can die from acute renal failure and/or severe damage to the urinary bladder. In addition to the removal of crystals, benefits of increased water intake include dilution of any noxious substances in urine, and more frequent urination to decrease bladder contact time with urine that may reduce the risks of urinary tract disease. For that reason, canned diets are usually prescribed as the first-line therapy for feline lower urinary tract disease.

The alkalizing nature of carbohydrate-laden dry food requires more than twice to three times the amount of acidification than does canned food increasing the risk of acidosis and kidney damage proportionally.

Acidification of the urine is not without potential toxicity. Dl-methionine causes hemolytic anemia, met hemoglobinemia, and Heinz body formation in cats. Dl-methionine is commonly used in dry foods as a urinary acidifier. Additional concerns about chronic acidification are its potentially detrimental effects on renal function and bone development.

Dry cat food is generally unpalatable to cats because of its dry nature. Palatability of dry cat foods is enhanced by animal fats, protein hydrolysates, meat extracts, acid, and the amino acids alanine, histidine, proline, and lysine. The preference for protein breakdown products and acidity may explain the use of "digest" as an ingredient in nearly all dry foods. Digest is "a microbiologically stable material resulting from digesting animal tissues. . . ." It is produced by enzymatic hydrolysis of animal tissues and by-products, which yield a viscous solution of amino acids, peptides, and fatty acids. Digest also contains significant quantities of phosphoric acid, which is added to stop the enzymatic degradation process and to preserve the product. Digest is sprayed onto the outside of cat foods at 4 to 10 percent of the final finished product or is incorporated directly into the food. Digest can enhance the palatability of foods by as much as two- to threefold over the uncoated product. Once incorporated into cat food, the phosphoric acid increases the amount of acid ingested by the cat. Because of this manufacturing practice, urine acidifiers should not be given to cats fed commercial cat foods, however, nearly all dry foods contain urine acidifiers, most commonly, dl-methionine. Chronic, overacidification leads to metabolic acidosis, demineralization of bone, calcium oxalate crystal formation and possibly renal damage. This may be a contributing factor in increase of incidence of calcium oxalate urolithiasis and high prevelence of chronic renal failure in middleaged cats.

......most dry pet foods are hard but brittle so that the kibble shatters without much resistance and so there is little or no abrasive effect from chewing. {Thereby giving no "teeth cleaning" benefit. Besides the cats teeth are a scissor bite not designed for a lot of chewing and with the lower jaw in a straight hinge there is no side to side chewing movement}
Very simply put it's not natural for cats (& dogs) to eat dry food, it was designed for our convenience not their health.

More reading here:

Many brands Wellness, Felidae, Holistic Select etc do come in a 12-13oz size can, which after opening can be refrigerated and yes you can even freeze canned food into portion sizes. Some stores offer discounts for buying by the case as well.

Instead of 2 cats going here & 2 cats going there, can you have someone come to your house for the weekend while you are away? Less stress all around.

Do you have the kidney cats' food dishes elevated 2-6 inches off the ground while they are eating? This is good to keep the excess stomach acid that tends to happen w/kidney issues in the stomach & out of the throat reducing nausea & vomiting as a result.

If the fountain is a good quality brand (ie PetMate etc) it is designed to be on all the time & there should be only mild heating of the plug. I've not purchased Hagen products before, however they have had this question asked in their site FAQ seems they are aware and are assuring their customers this is normal. You can always contact the company for more info.

Sometimes it takes a while for the cats to get used to the sound, running water and the different-ness of the fountains. It took my cat a few days before she was comfortable w/the PetMate fountain I bought & it was silent when the water full.
Avoid biting when a simple growl will do

The Spirit Lives As Long As Someone Who Lives Remembers You - Navaho Saying

Vindication ~ For all those pets who became sick or lost their lives from tainted pet food
Reply With Quote