Although our dogs and cats no longer look like their wolf or wild cat ancestors, their digestive tract remains almost identical.
Dogs and cats are carnivores, meaning that while they can eat fruits and vegetables as part of their balance diet, they need meat as the primary source of their diet to achieve optimal health.
Herbivores, Omnivores And Carnivores Explained
Latin for “meat eater”, classification refers to diets that consist of mainly meat.
Sharp, tearing teeth
A carnivore’s teeth are designed for tearing and slicing (not grinding).
Short digestive tract
High stomach acid PH (1–2) quickly digests meat protein and fat.
Amylase is not present in the saliva, meaning that the pancreas digests the carbohydrates.
Eats plants, digestive system has adapted to absorb nutrients from plant material.
Herbivores have square, flat molars designed to crush and grind plant material.
Long digestive tract
Plant material is difficult to digest, so the herbivore’s intestines are up to 10 times longer than their body length.
Amylase is contained in the saliva of the herbivore, which combines with the chewing action to break down carbohydrates.
Evolved to eat both meats, and plants and have adapted their digestive systems to accommodate this.
Tearing and grinding teeth
Omnivores have sharp canine teeth at the front of their mouth to cater for meat, and flat molars at the back to allow grinding of plant material.
Medium digestive tract
The digestive tract of an omnivore is capable of digesting meat-based proteins and fats whilst also being long enough to cater for vegetable matter.
Amylase is also contained in the saliva, that works alongside the chewing action of the mouth to help break down the coarse fibres and carbohydrates that make up plant material.
The Right Food
There is much debate on what is the “right food” for us as humans and our beloved pets. Many opinions are driven by commercial requirements of the companies that make the food, so it is difficult to get a clear view of what is right and wrong.
History can teach us so much as it gives a benchmark as to what was and should be a “normal diet”. Humans, cats, and dogs can be traced back approximately 3.5-4 million years in our current form. Although there would have been many challenges the diet would have remained the same with the first major change being during the industrial revolution around 1760, where people moved from a rural “cottage industry” to towns and cities as we see today.
Evolution can take thousands, or even hundreds of thousands of years, and even then, only small changes can be observed. Human, cat, and dog digestive systems are 99.9% the same as our ancestors. All species can adapt to short term changes in diet, which would have been essential for survival as food sources would have been in variable supply.
The issue arises when an animal is exposed to inappropriate food for their entire lifetime.
In humans, it is widely known that the consumption of fast food can be detrimental to health. Although one fast food meal wouldn’t cause lasting harm, eating high calorie, nutritionally devoid food for a long period of time and not consuming any fruit or vegetables can lead to a number of serious illnesses.
For cats and dogs, the consumption of large quantities of cereals, grains, rice, and other refined carbohydrates for long periods of time with the exclusion of meat can also be linked to serious illnesses.
The Ancestral Diet:
Cat & Dog
Further to a cat and dog’s natural preference to eat meat, we can also look at the ancestral diet to understand the ideal intake. The modern-day dog, the Timber wolf and the Tundra Wolf are classed under the umbrella of the Grey Wolf as Canis Lupus and they share over 99.9% of the mitochondrial DNA (Mitochondria being part of a cell that converts the chemical energy from food into a form that the cells of the body can use) which means the ideal diet of the wolf is also the ideal diet for your dog.
Similarly, a domestic cat may be traced back to Miacoidea between 33 and 66 million years ago, with a more recent ancestor, the African wild cat, all having the same similar digestive system.
A wolf and a wild cat would have consumed the whole animal, possibly excluding the feathers or fur. We can therefore get an insight to the nutritional requirements of a modern-day pet by looking at the composition of the whole prey. The following table is taken from a nutritional analysis of whole prey and clearly shows the macro nutrient profile (Protein, Fat, Carbohydrate and Ash (Mineral)) content; See full report from: *Dierenfeld, E. S., Alcorn, H. L. & Jacobsen, K. L. (2002). Nutrient composition of whole vertebrate prey (excluding fish) fed in zoos.
|Prey Species||Crude Protein %||Crude Fat %||Ash (MInerals) %|
As can be seen from the charts, dried mass protein content varies between 42.3 – 65.2% with fat content ranging between 15.8 – 41.4%.
Animal fats are a very important part of both dog and cat nutrition, providing a source of essential fatty acids (EFA’s).
The source of the macro nutrients is also important. Animal protein contains all of the amino acids essential to dogs and cats in the correct quantities for overall health. Plant proteins are often missing amino acids such as arginine, taurine, methionine, lysine and tryptophan.