A more in-depth review of why cats are obligate carnivores

I came across an article in the Journal of American Veterinary Medicine Association (JAVMA) to help emphasize the point that cats are obligate carnivores and NEED to eat animal matter.  The article is called “The carnivore connection to nutrition in cats” and it was written by a veterinarian.  I’ll highlight a few of the important parts:

Cats are strict carnivores that rely on nutrients in animal tissues to meet their specific and unique nutritional requirements

This is a straight-forward statement made by a veterinarian clearly acknowledging that fact that cats are true carnivores.

The natural diet of cats in the wild is a meat-based regimen (eg, rodents, birds) that contains little CHO; thus, cats are metabolically adapted to preferentially use protein and fat as energy sources.

As I’m sure many cat owners recognize, cats have retained their very powerful prey drive and will still eagerly hunt mice and birds.  They may not always eat them, but that’s because we feed them so well as caregivers.  But the emphasis here is on the fact that their natural diet contains little carbohydrates (CHO).

adult cats require 2 to 3 times more protein in their diet than adults of omnivorous species.

This is critical for cats, especially when it comes to feeding dry food.  Choose a grain-free kibble with no lower than 35% protein  for cats, but ideally choose a food such as Orijen with 40% or more protein with meat being the primary source of protein.

cats continue to use protein (eg, dispensable nitrogen in the form of gluconeogenic amino acids) for production of energy and in other metabolic pathways (eg, urea cycle), even in the face of low availability of proteins.

This is where there is a distinct difference between cats and dogs.  Dogs can adapt to low protein since they are omnivores but cats cannot, they must have high availability of protein in their diet.  The urea cycle is part of the production of urine – wonder why so many cats get urinary problems on low quality kibble diets?

cats also have need for increased amounts of specific amino acids in their diet: taurine, arginine, methionine, and cysteine. These specific amino acid requirements of cats have likely been determined on the basis that their natural diet contains an abundance of each of these specific amino acids

The physiology of cats is built such that it minimizes wasting energy by expecting an abundance of pre-made amino acids to be available through the diet.  Omnivores like dogs and humans have developed metabolic pathways to enable us to create these amino acids when we are in need of them and we don’t get them from our diet.

cats lack salivary amylase, the enzyme responsible for initiating CHO digestion. In addition, cats also have low activities of intestinal and pancreatic amylase and reduced activities of intestinal disaccharidases that break down CHOs in the small intestines.

More evidence that the physiological makeup of the cat is meant to take in foods that are easy to break down and readily bioavailable.  Proteins are relatively easy to breakdown compared to complex carbohydrates (CHOs).  Most omnivores have salivary amylase to start the breakdown of carbs early since they are more difficult to breakdown.

The water needs of cats reflect their early status as desert-dwelling animals and their development as strict carnivores that obtain most of their water requirements from consumption of prey. Cats have a less sensitive response to thirst and dehydration than dogs or other omnivores, and they adjust their water intake to the dry-matter content of their diet rather than the moisture content.

I don’t know about you, but I rarely see my cats drink water compared to my dog.  Kibble diets are unnaturally dry for cats and can lead to issues if your cat doesn’t make up for the lack of water in his diet.  You can avoid these issues by soaking the kibble before feeding, mixing kibble with wet food or feeding raw food that will have a high moisture content.

The following table was taken from the article as well, and demonstrates the nutritional makeup of the cat’s natural diet –  the rat carcass.  AAFCO determines the minimum nutritional requirements for commercial pet foods which clearly does not match the composition of the natural diet.  But nonetheless, as I already said, ideally try to choose a cat food that has 40% protein or higher.  This can be difficult with canned cat food since the moisture dilutes the as-fed protein content on the label.  But a canned food with about 9% as-fed protein will generally give your cat 40% dry-matter protein which is ideal.

Comparison of nutrients in selected diets consumed by cats

Nutrient	Rat carcass	Canned growth diet	Canned maintenance diet	AAFCO*
Protein (%)	55	45.2	49	26
Fat (%)	38.1	25.4	36.2	9.0
Carbohydrate(%)	9.1	19.9	6.9	–
Fiber (%)	1.2	2.9	0.6	–
Moisture (%)	63.6	75.6	69.6	–
Calcium (%)	1.15	.0.94	1.09	0.6
Phosphorus(%)	0.98	0.78	0.95	0.5
Vitamin A(U/kg)	84,800	–	–	5,000
Vitamin E(U/kg)	33	–	–	30
Thiamin(mg/kg)	5.8	–	–	5.0
Riboflavin(mg/kg)	10.7	–	–	4.0
Niacin(mg/kg)	156.6	–	–	60
Folic acid(mg/kg)	2.8	–	–	0.8
Pantothenic acid(mg/kg)	54.9	–	–	5.0
Cobalamin(µg/kg)	22.5	–	–	20
Iron (mg/kg)	288	–	–	80
Zinc (mg/kg)	71.4	–	–	75

*Nutrients are expressed on a dry-matter basis.

AAFCO = Association of American Feed Control Officials.

– = Not determined.

The carnivore connection to nutrition in cats

Debra L. Zoran

Journal of the American Veterinary Medical Association, December 1, 2002, Vol. 221, No. 11, Pages 1559-1567

Where’s the science behind Science Diet?

Since we have so many veterinarians out there who recommend Science diet to us, I took the liberty of looking through all of their foods and picked Hill’s 6 favorite ingredients:  whole grain corn, whole grain wheat, brewer’s rice, corn gluten meal, soybean meal and powdered cellulose.

Science, history and logic tells me that dogs are omnivores that primarily eat meat while cats are obligate carnivores and ONLY eat meat.  Take the evidence from pre-commercial pet food history when dogs were fed meat from table scraps and cats had to survive off of the pesky mice that they were kept around to hunt.  Or perhaps look at the digestive physiology of dogs and cats – both have very short digestive tracts meant to digest food that is easy to break down – not food that is full of starch, complex carbohydrates and fibre.  Both dogs and cats have teeth meant for ripping and tearing meat, not molars for grinding grasses and grains like a horse or cow.  How about the logic behind the fact that dogs and cats lack salivary amylase (an enzyme that breaks down carbohydrates) – they are not intentionally eating carbohydrate rich foods and therefore would not need to break down carbs before it reaches their digestive tract BUT they do produce pancreatic amylase to break down any carbs that would be found in their prey’s intestines.  We can also trace their lineage back to their ancestors – wolves and wildcats that hunt and eat other animals for meat.  Keeping these facts in mind, lets take a look at Hill’s favorite ingredients.

1. Whole grain corn:  “whole grain” does nothing but point out to us that they are in fact including grain.  Corn is only about 50% digestible for dogs (think about it… when you eat corn, don’t you usually see it come out the same way?) and when it’s one of the top ingredients, then nearly 50% of that food is wasted!  Corn is primarily carbohydrates and fibre – dogs are omnivores and though they primarily get energy from protein and fat, they do need some carbs.  But the amount of carbs in these foods is ridiculously high for a dog!  I already pointed out that our fuzzy companions do not have salivary amylase, so corn gets a late start in digestion and in combination with their short digestive tracts, our dogs and cats hardly get a chance to digest their food!  So all in all, save the corn for the chickens and cows or maybe as a future fuel source.
2. Whole grain wheat: Again, “whole grain” means nothing when it comes to dogs.  Just like in humans, there is strong suspicion that all dogs have some level of sensitivity to gluten.  Where does gluten come from?  Grains, and wheat is one of the worst.  I won’t go into all the details about gluten here (save that for a future post) but gluten causes inflammation in the intestines, which erodes the villi therefore harming your companion’s digestive system.  This erosion causes a whole host of problems from diarrhea, declining nutrient uptake, and bloat due to fermentation of undigested wheat. Again, let’s save this one for the chickens and cows.
3. Brewer’s rice: The small milled fragments of rice kernels that have been separated from the larger kernels of milled rice.  A by-product of rice milling that is missing many of the nutrients that whole rice contains. Yummy… rice hulls?  Yes, rice is much less inflammatory than other grains and whole grain brown rice is one of the better carbohydrate sources for cats and dogs, but rice hulls contain almost no nutrition and is primarily a filler.  Another terrible ingredient for cats and dogs.
4. Corn gluten meal: More corn?!?!  Corn gluten meal is the dried residue after the removal of the larger part of the starch and germ, and the separation of the bran by the process employed in the manufacturing of corn starch/syrup.  An inexpensive by-product of human food processing which contains some protein but serves mainly to bind food together. When it is one of the first ingredients, they likely added it as filler and to bump up the protein content with low quality, unavailable corn protein.  I don’t know why Hill’s seems to think they’re feeding chickens… but this is a terrible ingredient for dogs or cats!
5. Soybean meal: The product obtained by grinding the flakes which remain after removal of most of the oil from soybeans.  A poor quality protein filler used to boost the protein content of low quality pet foods. It has a biologic value of less than 50% of chicken meal meaning that though it may increase the protein content of the food, it is not premium or balanced protein but rather low quality, unavailable protein.
6. Powdered cellulose: Ah, this is my favorite ingredient.  Purified, mechanically disintegrated cellulose prepared by processing pulp from fibrous plant materials. Dried wood is the most common source for cellulose and it is cleaned, processed into a fine powder and used to add bulk and consistency to cheap pet foods. Your dog or cat may be chowing down on some lovely sawdust.  All these fantastic fillers means your dog or cat has to eat more food than he should be eating to get a minimum balance of nutrients and minerals from the relatively small amount of meat products in the food.  What does this lead to?  Constipation, obesity, nutrient deficiencies, massive stools, and buying excessive amounts of this expensive Science Diet food because your companion has to eat so darn much of it!

So get your dog or cat off of Science Diet and onto a more biologically appropriate, healthy and beneficial diet such as raw food, home cooked or a high quality kibble such as Orijen or Acana.  You will save money in the long run from less veterinary visits and spending less money of premium food opposed to expensive chicken feed but the best part is how healthy and happy your furkid will be 🙂