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Outlined below are just a few of the unseen, but still very real biochemical differences between cats and dogs. Look these over and you will be even more convinced that cats are different!
Also called retinol, this vitamin is required at the cellular level by both cats and dogs.
Cats – Process little or no enzymes that will break down the plant-produced carotenoids. Must eat preformed active Vitamin A (that is, Vitamin A that already has been converted from carotenoids to its active form by some other creature such as a mouse or rabbit). Here’s a good example of why cats are called strict carnivores ... they need to eat some other animal in order to "borrow" its active Vitamin A!
Dogs – Have enzymes in the lining of the intestine that can break down plant carotenoids and convert these into active Vitamin A.
An essential B vitamin (essential means must be eaten, can’t be made inside the body’s chemical factory.)
Cats – Can obtain Niacin only by eating the preformed vitamin. Cannot convert Tryptophan to niacin.
Dogs – Obtain Niacin in two ways. One is by converting a dietary amino acid call Tryptophan into Niacin, and the other way is by eating preformed Niacin.
A building block for proteins, it is an amino acid. Arginine is vital to many of the animal’s internal chemical factory’s functions. No Arginine and the entire factory goes on strike!
Cats – Are extremely sensitive to even a single meal deficient in Arginine and are unable to make their own Arginine within their chemical factory. Cats need lots of protein, and Arginine is involved in aiding the elimination of the protein waste products so the wastes don’t pollute the whole factory!
Dogs - Are not very sensitive to low levels of Arginine in their diets and produce enzymes internally that can aid production of Arginine.
An amino acid that is not built into proteins, but is distributed throughout most body tissues. Taurine is important for healthy functioning of the heart, retina, bile fluid and certain aspects of reproduction.
Cats – Must eat preformed Taurine. And since it is not found in plant tissues, cats must consume meat to obtain Taurine. Therefore, Taurine is essential in the diets of cats. Here again, meat has to be supplied to the factory so the Taurine can be extracted for its many uses.
Dogs – Make their own in their internal chemical factory.
It is a compound made from a sulfur amino acid (SAA) called Cysteine.
Cats – Have a much higher requirement for SAA than other Mammalia and are the only creatures to manufacture the Felinine chemical. Felinine’s role in the overall function of the chemical factory is unknown, but like most factories whose wastes generate offensive odors, any Felinine present in the male cat’s urine alerts the neighbors that the factory is up and runnin’!
Dogs – Don’t know and don’t care what this stuff is.
Cats – If fed a perfectly balanced and 100-percent digestible protein in a diet, the cat will use 20 percent of that protein for growth metabolism and 12 percent for maintenance. Here’s any easy way to say it ... cats need more protein in their diets than dogs do.
Dogs – If fed a perfectly balanced and 100-percent digestible protein in a diet, the dog will use 12 percent of that protein for growth metabolism and only 4 percent of that protein for maintenance. Here's an easy way to say this ... dogs need less protein in their diets than cats.