Of course, all animals are biologically equipped to assimilate and digest foods they were designed to eat. For example, earthworms are naturally designed to process dirt. The entire GI tract of worms, from the mouth to the other end where waste is excreted, was designed for this purpose.

Cows are designed to eat grass, and their GI tracts are set up perfectly for this. They have big, round, flat teeth used to grind grasses and an unbelievable range of motion in their mandibles, allowing them to chew, chew, chew, and chew. Cows have a lot of range of motion laterally in their jaws.

Dogs and cats do not have this range of motion in their jaws. Their jaws move up and down only, like a trap door or a hinge, because dogs and cats are gulpers, not chewers. They don't have chewing teeth. Dogs and cats have incredibly sharp interlocking  teeth designed to rip and tear flesh. They are not designed to consume or chew kibble. 

They also have very short GI tracts compared to vegetarian animals that need to ferment foods, as carnivorous animals consume foods with potentially very heavy pathogen loads. The bodies of carnivores are designed to get foods in and back out very quickly.

They thrive consuming fresh, living, whole animals. But carnivorous animals do not eat clean foods. Dogs and cats did not evolve to consume sterile foods. They have digestive tracts that are designed to be resilient and handle the loads of naturally-occurring bacteria that are present in the foods they eat. Their food in the wild was moisture-dense, meaning the prey they consumed was primarily water.

So one of the reasons we've been able to deceive ourselves into believing that feeding solely convenience pet foods is good for dogs and cats is because we do not see them suffer immediately from malnutrition.  

For a hundred years our pets have been fed inappropriate diets that have kept them alive, but far from thriving like their wild relatives. Instead, we've created dozens of generations of nutritionally weakened animals that suffer from degenerative diseases linked to nutritional deficiencies - unfortunately the traditional veterinary community has not acknowledged.

The truth is that our pet population provides a place for recycling waste from the human food industry. Grains that fail inspection, uninspected pieces and parts of waste from the seafood industry, leftover restaurant grease, deceased livestock, and even  roadkill is collected and disposed of through rendering -- a process that converts all sorts of human food industry waste into raw materials for the pet food industry.

These raw materials are purchased by huge pet food manufacturers - makers of the big name brands your parents and friends have probably used for the last 50 years. 

These manufacturers blend the rendered fat and meat with a large amount of starch fillers. They add bulk vitamin and mineral supplements, and then they extrude the mix at high temperatures, creating all sorts of toxic reactions including advanced glaciation end products and  heterocyclic amines. They call this "pet food" and sell it to customers at an unbelievable profit.

Is the entire system flawed? Yes. But pet food industry giants are realizing that pet owners are becoming more educated about their flawed system, and they are trying to clean up their image. We are beginning to see words like "natural" and "no by-products" on labels. We're beginning to see "grain-free" and "naturally preserved" on labels as well. Manufacturers are hearing the grumbles of educated pet owners and are changing their marketing to try to regain lost customers. But is feeding kibble as a stand alone,truly a species appropriate diet? We believe not. 

Number one, carbohydrates are not a necessary component of a carnivore's diet. Cats have no taste receptors for sweet flavors and have low rates of glucose uptake in the intestine. They should not be fed any type of grain that metabolizes into sugar.

Cats have no  salivary amylase to break down starches, and dogs have very low amylase secretion.

The intense heat used to process commercial pet foods diminishes or destroys the benefits of vitamins, minerals, and enzymes in food. Processed pet foods require supplementation to replace lost nutrients.

The heating process also significantly reduces the digestibility of amino acids in pet food.

And digestibility of meat-based protein is proven to be superior to plant-based protein - the type used in most inexpensive commercial pet foods -- for dogs and cats.

So in a nutshell, for 99.99 percent of their time on earth, dogs and cats have consumed a natural diet. For .01 percent of the time, they have consumed an  extruded, processed diet. Dogs and cats evolved to consume a low-carbohydrate diet. But for the last century, the majority of pet owners have fed pets a high-carbohydrate, low-moisture diet. This has created significant metabolic and physiologic stress, and convenience pet foods have become the root cause of most of the inflammatory processes and degenerative disease that plague today's dogs and cats. 

So to summarize and simplify, feeding kibble alone is not species appropriate or metabolically appropriate.   

Fresh! Fresh! Fresh!