He knows where the cat food is, and he mostly eats cat food, but there are times he'll eat some of the dogs food, even when there is cat food available for him.

Why is this happening? The cat food we currently get doesn't seem to be a problem; it's as if he wants variety.

I wanna put on record that my dogs and cats actually share the same water bowl (related question Is it harmful to allow animals of different species to share the same water bowl? ). Does this play a role as to why he might also be eating the dog food?

  • A word of caution, cats can have real issues with PG (Propylene Glycol) which is sometimes used in dog food. Just something to look out for.
    – Ian
    Sep 16, 2016 at 19:06
  • Probably he does just want variety, and dog food smells enough like food to be a possibility (and one he can easily access). My cat wanted whatever we were having, veggies like eggplant (even though cat's can't digest them), just because we were having it and it smelled good to them.
    – Megha
    Jun 15, 2017 at 5:25
  • I only have a cat, but once I checked the dog equivalent of the cat food I buy for him (same brand, same type canned food) and the contents of the dog food was exactly the same as the contents of the cat food, 1:1. Maybe the food you get is also very similar if not exactly the same and the cat just doesn't care and goes to whatever is closer.
    – NovaLogic
    Dec 29, 2017 at 14:08

2 Answers 2


Differences between Dog and Cat Food

The major difference between dogs and cats is that dogs are scavanging carnivores (they do best when eating animals, but can digest plant material as well) and cats are obligate carnivores (they can only digest animals). Cats can eat plants, but lack the digestive enzymes to break down the nutrients into a usable form. Because of this difference, cat food has more supplimentation (or supplimentation of a different form) to ensure that the cats get enough of the nutrients that they need. For example:

  • Taurine. Taurine is a essential nutrient for cats, and "Dog food does not contain enough taurine to meet the normal requirements for a cat." (Cheryl Yuill, DVM, MSc, CVH, VCA Hospitals)
  • Vitamin A. "Dogs have the ability to convert beta-kerotene to vitamin A. Cats on the other hand need pre-formed vitamin A in their diet, which can only be found in animal tissues. " (Joseph Hahn, College of Veterinary Medicine - University of Illinois). Beta-kerotene is easily/cheaply found in carrots and other vegetables, so it is likely that is how dog food is formulated to include Vitamin A. Since cats cannot use beta-kerotene, they will become deficient.
  • "Arachidonic acid, a necessary fatty acid, can be synthesized by a dog using linoleic acid. The cat is unable to do this and needs to ingest arachidonic acid in their diet. This, too, can only be found in animal tissues." (Joseph Hahn, College of Veterinary Medicine - University of Illinois).
  • Higher protein content. Cats need more protein than dogs. While less protein won't cause any illness, it may make them lethargic and loose muscle mass.

Is Your Cat Eating Enough Dog Food to Be a Problem?

One recommendation is that treats should not exceed 10% of a pet's caloric intake (Pets.webmd). You can look up the calorie counts of your foods, then figure out how much dog food (and other treats you may be feeding) is 10% of your cat's cat food intake to determine if it's just a harmless habit or something you should seriously be worried about.

If you need to stop your cat's dog food intake, I would recommend switching both animals to meal feeding.

Why is the cat eating dog food

I can speculate, but honestly, only the cat really knows.

My best guess is that if you're feeding dry food, cat food manufacturer's coat it with animal digest to make it smell more palatable, and I suspect that dog food manufacturers do the same. Animal digest is irresistable like an open bag of potato chips to a human, so since it smells like food, he eats it.


I have a cat that will eat dog food. I have watched him and he sometimes thinks that he is a dog. He goes outside with the dogs in the morning then when coming back inside they stop for a drink of water and a quick bite of food and the cat does the same at times. He then proceeds to his cat food. I think that this has become just a mimicking habit as the cat is young and has not been around other animals but the dogs. The cat also likes to try human food and wants to try whatever you are eating.

Not the answer you're looking for? Browse other questions tagged or ask your own question.