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Written by leading veterinarians to provide you with the information you need to care for your pets.

Nutrition Nuggets is the newest offshoot of petMD's Cat Nutrition Center. Each week Dr. Coates will use her expertise and wisdom to blog about the intricacies of cat nutrition.

Everything You Need to Know about Cat Food and Protein

April 03, 2015 / (5) comments

Informed owners know that protein is a vital part of their cat’s diet, but a greater understanding of protein is necessary to make good decisions about what to feed your cat.


Protein plays many roles in a cat’s body. It is essential to making and maintaining muscle, hair, and other anatomical structures. Parts of the immune system (e.g., antibodies) also contain large amounts of protein, and unlike many other animals, cats use protein as their primary energy source.


Cats need to eat a lot of protein to meet all these needs, but the protein that cats take in doesn’t directly get incorporated into their bodies. First, the digestive system breaks down dietary proteins into amino acids that can be absorbed and then reassembled into the specific types of proteins that the cat needs at that time.


All protein is made from only 23 different amino acids. A cat’s own body is able to make 12 amino acids from simpler building blocks. These 12 amino acids are called non-essential amino acids since they don’t specifically need to be present in a cat’s diet.


However, cats cannot make the other 11 amino acids necessary for producing all the proteins their bodies need. These are called essential amino acids. Arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine, and taurine are essential amino acids for cats.


A lack of any essential amino acid in the diet will eventually lead to health problems. For example, arginine deficiency causes toxic levels of ammonia to build up in the body, resulting in vomiting, muscle spasms, seizures, coma, and death. A shortage of taurine induces cardiomyopathy (a serious form of heart disease) and central retinal degeneration and blindness.


How can owners determine if a food provides enough protein in general and, more specifically, all 11 essential amino acids that cats should be eating?


First, foods that display an AAFCO (Association of American Feed Control Officials) statement of “nutritional adequacy” (also known as a “complete and balanced” statement) contain at least the minimum amount of protein and essential amino acids that cats require. Ensuring that any food you offer has an appropriate AAFCO statement (e.g., growth and reproduction, adult maintenance, or all life stages) on its label is a good place to start.


Next, take a look at the food’s guaranteed analysis. The minimum protein percentage will be listed. If you have seen numbers close to the AAFCO minimums (26% for adult maintenance and 30% for growth and reproduction), the manufacturer is not providing more than the bare minimum cats need to survive.


Given a range of foods to pick from, cats seem to naturally gravitate towards eating a diet that provides approximately 50% of its energy from protein. High-quality canned foods more closely match this dietary preference than do dry, but if you offer cats both, they will pick and choose to meet their needs.


Now study the food’s ingredient list. Animal-based protein sources (e.g., egg, meat, dairy, and fish) contain more essential amino acids than do plant-based protein sources (e.g., soybeans or corn gluten meal). Products that rely on plants to provide most of their protein cannot provide all the essential amino acids cats need without supplementation even if the food appears to be “high protein” based on its guaranteed analysis. Select a cat food that includes meat, fish, or meat and fish meals at the top of the ingredient list.


Finally, feed your cat the food you’ve picked for at least a month. If you’ve followed these guidelines and your cats are thriving, you can be confident in your choice.



Dr. Jennifer Coates



Image: April Turner / Shutterstock


Comments  5

Leave Comment
  • Sorta True
    04/03/2015 09:55pm

    I have one that the vet and i would really like to see put on a little weight.

    Unfortunately, she's very picky. It doesn't matter how hungry she is, if it's not what she had in mind, she'll walk away.

    It doesn't help that she's on a low dose of chemo (Leukeran) and I've heard that chemo can alter the way things smell.

    I've tried really smelly cat food. I've tried gently heating the wet food so it's more fragrant. I've tried adding warm to hot water (making sure the food isn't too hot) to the food. Haven't tried turkey baby food yet simply because it doesn't seem smelly enough. That's probably next, though.

    I'm open to suggestions.

  • 04/05/2015 07:36pm

    It sounds like you are doing everything right. The only suggestion I have is to not switch foods too rapidly. Offer something new and as long as she's eating something (e.g., her old dry food) keep offering the same "new" option for at least a few days. If you rotate foods too quickly some cats will simply wait to see if anything better is coming down the road.

  • Making your own cat food?
    04/07/2015 11:51pm

    I would be interested in trying to rotate some homemade cat food into my pets' diet but don't know where to begin. I would not be totally replacing commercial food because that seems too risky until I know what I'm doing nutrition wise for my cats.

    I often have smaller than palm sized pieces of meat left over from the meals I make myself. I also have things like shredded carrots, dark green salad leaves and tomatoes on hand.

    Is there somewhere I can find nutritious cat food recipes? Should I use about the same serving size of homemade cat food that I do of commercial?

    Thank you for this informative article.

  • 04/09/2015 12:16am

    The veterinary nutritionists at Petdiets.com and BalanceIt.com can formulate recipes from many different ingredients that are nutritionally complete for cats.

  • 04/09/2015 01:32am

    Thank you very much, I will give them a look tonight.