How the Nutritional Needs of Cats Differ from Our Own

People project a lot from their own lives onto their pets, including food preferences, beliefs, and habits. Often we think of dogs as little furry people and cats as small dogs, but when it comes to how their bodies need and use certain key nutrients, that’s not the case.

How Do We Know What Cats Need?

“Well, it was a lot of hard work over many decades. There are a lot of nuances to determining requirements because you have to determine the requirements for what and for whom and under what conditions,” says Jennifer Larsen, DVM, PhD, a board-certified in veterinary nutrition and an assistant professor of clinical nutrition at the Veterinary Medical Teaching Hospital at the University of California, Davis.

Calling two of her mentors, Dr. Quinton Rogers and Dr. Jim Morris, the godfathers of feline nutrition, Larsen explains that much of the early work focused on the nutritional needs of growing kittens, later extrapolated to adult cats.

There are sometimes gaps in this method, however. For example, Larsen explains, “The aromatic amino acids – phenylalanine and tyrosine – work together... so we usually talk about them together. We determined the requirements (of these amino acids) for growth, but subsequently discovered that the requirement to maintain normal melanin and hair coat, meaning to maintain a black cat to be black, was twice the requirement needed to grow a cat normally. So that’s probably an extreme example, but I think it’s a good example of one of the limitations of extrapolating growth data to maintenance requirements.”

Some of the other dietary needs begin with the nutritional needs of people. Many of the nutrient requirements indeed are conserved across species, but there are some exceptions.

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Cats vs. People

While dogs do process and use a couple of key nutrients differently than people do, the different nutrient needs of cats are the bigger issue.

“Cats are certainly nutritionally interesting,” Larsen says. “As far as companion animals go, they are fairly unique in how they evolved and their strict carnivorous status. Dogs share some of their nutritional peculiarities, but not to the same degree.”

Fundamentally, nutritional needs fall into two camps:

• Essential nutrients required in a diet because the body does not make any or enough on its own
• Non-essential nutrients that the body makes on its own

“If you think about it from an evolutionary point if view, which is kind of fun to consider,” she says, “we talk about essential amino acids and non-essential amino acids. We always sort of assume that the essential ones are the important ones, but if you think about it from evolution’s point of view, the essential ones were the ones that were readily available in food stuffs. Therefore, why should we conserve all these enzymes to make it when it’s really expensive and metabolically demanding to conserve those? But, on the other hand, perhaps metabolically or physiologically the dietary non-essential ones are more important because evolution didn’t leave it up to chance that you would stumble across that in your diet and eat enough of it.”

• Cats cannot make arginine, an amino acid, which is used by the liver to make enzymes important for processing metabolic by-products in the body.
• Cats cannot make taurine, another amino acid. Without it, cats can develop lesions on their retinas, causing visions issues. They can also develop dilated cardiomyopathy, which Larsen describes as, “their heart is sort of this big baggy sack that doesn’t contract blood as it should.”
• Cats cannot make enough niacin, a vitamin. Many animals can use tryptophan to make niacin, but a cat’s ability to do this is really limited, so it’s essential in the feline diet.
• Cats cannot make enough Vitamin A. Larsen says, “We thought for a really long time that cats were unable to make Vitamin A from beta-carotene the way that we can and the ways that dogs can. Now, we know they can. They just do it in very small amounts. It’s probably not nutritionally significant, so it’s really important that cats have a source of preformed Vitamin A.”
• Cats don’t make Vitamin D through their skin like we do. They also don’t convert very well the plant form for Vitamin D (ergocalciferol) into the animal protein form of Vitamin D (cholecalciferol).
  
  “Dogs and cats can’t make Vitamin D in their skin. We know that for sure,” Larsen says. “It’s kind of interesting because they have all the precursors, the necessary enzymes, to make it in their skin, it’s just that it gets shunted off into another pathway. So, it’s all about enzyme activity and where it’s going.”
• Cats have a low conversion rate of linoleic acid to arachidonic acid, an Omega-6 fatty acid. Veterinarians don’t often see arachidonic acid deficiencies in cats, but it’s an essential nutrient, especially for reproduction in queens.
• Cats are more finicky. Compared to dogs, cats can develop feeding behaviors and palatability issues along with weird fixations about flavors and textures.