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Ask a Vet: Is Wet Food or Dry Food Better for Cats?

Canned food and kibble seem like wholly different things, but their only difference is water content.

 |  Dec 10th 2013  |   68 Contributions


I have been writing for Catster for nearly a decade. It was early in my first year that I learned one of the basic tenets of writing about animals on the Internet: Write about cat food or dog food and ye shall be flamed.

Whenever I write about pet food I think of Kathy Bates' character in The Waterboy. To her, football (or as she put it, foosball) was the devil.

Well, for every cat food and dog food out there -- no matter whether dry or canned, homemade or commercial, raw or cooked, premium or bargain basement -- there is someone (or usually many someones) who believes it is the devil. And they're not afraid to say so.

Why do people go berserk in the comments whenever I (or anyone) write about cat food? I have no explanation for this. People's opinions are held so strongly that discussing cat and dog food is like discussing religion. It's best not to do it. (I once wrote a tongue-in-cheek post asking why people get so fired up about pet food, comparing their zeal to that of people defending their religions, and predictably I was deluged with furious comments from livid people.)

Photo of Dr. Eric Barchas by Liz Acosta

Another insufferable insult that is thrown in my face by food-is-the-devil types is the slanderous assertion that veterinarians (and therefore I) have been bought off by pet food companies. No such luck. Iams once flew me to Dayton, Ohio, to tour its plant. Purina once flew me to Atlanta, Georgia, for a nutrition symposium. I appreciated both trips, but I continue to feed a different brand to my pal Buster -- a brand that has never given me a penny. In fact, I buy Buster's food at the pet store just like everyone else, and I don't get a discount. Those two trips mean that I have benefitted far more than most vets from pet food company largess (if that's what you'd call it). If I haven't been bought off, then neither have most other vets.

There is no doubt about it. I'm reluctant to write about pet food. So when my editors at Catster asked me to write a column about dry food versus wet food I tried to ignore the suggestion at first. But the suggestion kept coming up, and in fact it's a very good question. So, livid commenters be damned. I'm writing about cat food this week.

I'll cut to the chase: Cats are very adaptable creatures, and I have known thousands of cats thriving on canned food. I also have known thousands of cats thriving on kibble. In fact, most cats can do quite well on either canned or dry food. The currently ascendant school of thought holds that canned food is better than dry, but it cannot be said that either type of food is definitively better than the other.

Canned food and kibble seem like very different things. But in fact they differ significantly only on one parameter: water content. Canned food has more water. In general they're otherwise nutritionally equivalent.

For many years, a predominant school of thought held that dry food was better for cats' teeth. The theory was that the chewing involved in consuming dry food helped to clean debris off the teeth and reduce the severity of dental disease.

If you feed your cat kibble, please try the following experiment. Go barefoot in the house for several weeks. When you step in cat vomit in the middle of the night, turn on the light and inspect it. I'll wager that most of the kibbles will be unchewed. Cats don't naturally chew their food -- they tear, shred, and swallow whole. Most of the veterinary dental experts I know believe that genetics and oral chemistry have a far greater impact on dental health than does diet. Tooth brushing no doubt can make a big difference, but it appears food does not. (For those who believe that natural diets prevent dental disease in cats: Sorry, but no. Wild cats -- truly wild ones such as tigers, African lions, and bobcats -- develop dental disease while eating 100-percent natural and species-appropriate diets in jungles, savannas and forests.)

Although many vets now question the dental benefits of dry food, almost every vet would agree that cats are better off when they consume more water. Water helps prevent symptoms of FIC/FLUTD (urinary tract disease), and it also is theorized to reduce the workload of the kidneys. Wet food has more water.

Many people also believe that wet food helps reduce obesity in cats. This is not because it is less calorically dense than dry food (it is -- it has more water, and water has no calories). It is because it goes bad if it's left out all day. People therefore tend to feed wet food in meals, but dry food is generally left out in a massive all day, all-you-can-eat buffet for the cat. Unlimited access to food predisposes most species, including cats and humans, to obesity.

However, there is one bit of sand gumming up the engine that would drive canned food to a slam-dunk win over dry food. I'm talking about hyperthyroidism. Studies have shown a positive correlation between canned food consumption and thyroid gland problems in cats. Nobody knows why; some people have speculated that materials from the can itself may be involved. Thyroid disease is rarely fatal, but it is a big deal in the world of cats.

So: Canned food and dry food appear roughly equal in the world of dental disease. Canned food appears better for urinary health. Dry food appears better for thyroid health. In the end it's a toss-up.

I have been criticized in the past for not providing "clear-cut answers" to questions such as whether it is better to feed wet food or dry food. If you were hoping for a definitive answer, then I'm sorry to disappoint you. But we're not talking about religion. We're talking about cat food, and I don't believe that cats are well served by dogmatic answers to such questions.

Although I can't provide a clear-cut answer to the wet vs. dry food question, I can provide some clear-cut advice. If your cat is healthy, pick a high-quality food, wet or dry, that your cat finds palatable and that works for you. Feed it in meals, not an all-you-can-eat megabowl. And brush his teeth.

Read more about cat food and more by Eric Barchas:

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