Cats are Carnivores
Many of us have heard that cats are obligate carnivores, but what does this mean and how do we know? It means that they must eat meat. So, let’s look at their anatomy and physiology to see why.
Carnivores have long sharp canine teeth for killing and holding on to prey, short and dull incisors for grabbing and sharp premolars for tearing meat. They do not have any grinding teeth to grind plant material. They also do not have the enzyme amylase in their saliva which starts the digestion of carbohydrates. And their jaws only open and close, but do not move side to side or front to back as is needed for grinding plant material. You will also notice that herbivores have muscular lips for grasping plants, but carnivores often have floppy lips with little mobility. Remember the giraffe at the zoo?
As we look further, we see that the digestive tract of a carnivore is also very different from a plant eating animal. A carnivore’s stomach is a larger portion of the digestive tract, so they can eat a large amount of meat at once when they have a successful hunt. The acid content in the stomach of a carnivore is 100 to 10,000 time stronger than an herbivore to help break down the meat proteins and kill any ingested bacteria. Since meat requires much less digestion time than plants, a carnivore’s intestinal tract is 1/3 to ½ as long as an herbivore’s when compared to body length.
Cats and dogs share all these characteristics, except that dogs do have a few grinding molars. But cats take things a little further. All mammals can convert protein to sugar for energy, but for us, this is done when the diet does not provide enough carbohydrate. Since cats in the wild would not eat carbohydrate, their enzymes convert protein to energy at a constant rate no matter how much carbohydrate is in the diet. So the extra energy derived from carbohydrate is often stored as excess fat. If we try to restrict calories by restricting protein, the process will continue, and they will use their own body muscle for energy. If they stop eating completely because they don’t feel well, or we try to force a diet change, they will try to mobilize their body fat for energy as well. But this system is not well developed in cats and the fat can clog of the liver, causing fatty liver syndrome which can be fatal if not treated aggressively.
So, you can see that cats are perfectly designed to eat a meat based diet and need to eat every day, often preferring to eat multiple small meals throughout the day. Some people estimate that a feral cat will eat up to 8 mice daily which explains why our cats like to graze all day.