Wet food or dry food? What is better for your cat?
Want to start a fight among cat lovers? Offer an opinion on the “best” food for cats, whether wet or dry.
The controversy over whether wet cat food or dry cat food is best for cats is a controversy for a reason: there isn’t one formulation that is clearly, scientifically, unequivocally better than the other. Each type has its own benefits.
And regardless of your stated preference for one type of food versus the other, the poorest quality canned diet will never hold a candle to the highest quality kibble. And vice versa. In other words, there is more to the discussion than simply wet versus dry.
You will have your own reasons for choosing one formulation or another for your cats. Budget, lifestyle, and personal preferences certainly come into play when you’re shopping the cat-food aisle. But the cat should have a say, too.
Years ago, we brought a six-year-old 160-pound Great Dane into our lives. We visited our beloved vet, Dr. Flavia Zorgniotti, and I remember asking her what to feed this thing. I didn’t know anything about dogs, and I wanted her to recommend a particular type or brand of dog food.
She said – and I’ll never forget it, “The best food for your dog is the food she does well on.” The same is absolutely true of cats.
First, your cat has to want to eat the food you give her. It doesn’t matter if you bought the most expensive, well-regarded, small-batch, boutique canned food ever made if she turns her nose up at it. Second, she has to do well on it. Is she bright-eyed and glossy? Is her skin clear and supple? Is she full of energy and a healthy weight? Is she peeing and pooping normally?
In other words, the decision about the kind of food to serve your cat – wet or dry – is not a conversation you have only with yourself after reading this blog post. Ask your cat, and ask your veterinarian, too.
Dry cat food
Cats need to eat meat, not carbohydrates, to survive
Cats have evolved as obligate carnivores, meaning they need to eat animal protein to survive.
We humans are omnivores, meaning we can eat both plants and animals (the prefix “omni” means “all”). It might surprise you to learn that dogs are omnivores, too. But cats are not omnivores and they are not well adapted to eating plants. You wouldn’t feed a sheep a steak because a sheep’s digestive system isn’t designed to handle meat. It’s kind of the same thing with cats and plants.
You cannot feed a cat a vegan diet. Period. Cats need to get certain amino acids, like taurine, from their food, and no plants will provide them with taurine. We humans (and dogs) can actually manufacture our own taurine. Without taurine, or with an insufficient amount of taurine, cats can develop a heart problem called dilated cardiomyopathy, in which the heart muscle becomes weak and thin. Blindness is also a symptom of taurine deficiency.
What do carbohydrates have to do with dry cat food?
Nearly all dry cat food is extruded, which means meat and other ingredients are mixed into a kind of dough, cooked under pressure, and then forced through a die, like Play Doh. The little kibbles are sliced off as they emerge from the die. In order to create the right texture of dough for extruding, some kind of carbohydrate or plant matter has to be added to the mix.
(As a side note, many dry and wet foods advertise themselves as “grain free.” This only means that the food does not contain a grain like wheat or rice. It does not mean the foods are carbohydrate-free. There are many plant sources for carbohydrates that are not grains, such as sweet potato or tapioca.)
Are carbohydrates safe for cats? There are two interesting facts around carbohydrates and cats. One is that cat saliva contains amylase, an enzyme that helps digest carbohydrates. You really can’t argue that a cat eating a carbohydrate is exactly the same thing as a sheep eating a steak when a cat’s saliva seems primed and ready to receive carbohydrates.
The second is that cats eat prey animals like mice and birds, and these creatures often have partially digested plant matter in their bellies when they meet their demise. Cats, left to their own devices, eat carbohydrates whether they planned to or not.
But studies have shown that cats are less efficient than some other mammals at processing carbohydrates. Cats’ digestive systems evolved to consume small prey animals and insects, which are mostly water and protein. Studies have shown that cats just don’t have the same kind of carbohydrate metabolizing enzymes that we omnivores do. They’re just not as good at digesting and using the energy from plant matter as we are.
Do the carbohydrates in dry cat food make it unsuitable for cats?
The answer is probably not, assuming you are careful about the kind and amount of dry cat food you feed. But let’s back up for a minute.
If you read other commentary on dry cat food you will read that dry cat food can cause obesity and diabetes in cats. It’s true that dry cat food is very calorie dense and if you have a cat with no self control and free access to a bowl full of delicious kibble, your cat will gain weight. And it’s true that excess weight and too many carbohydrates, along with other factors like inactivity, can lead to insulin resistance and eventually diabetes.
But does this mean that dry cat food causes diabetes? I scoured the scientific journals for some answers and the conclusion is that the relationship, if there is any at all, between dry cat food and diabetes is, at best, unclear.
One study explained what most cat owners already know about their pets: that cats commonly consume multiple small meals throughout each day, sometimes nine or even more! Two studies looked at how many carbohydrates a dry-food-eating cat could possibly consume at one of their itsy-bitsy meals, and the conclusion was that it wasn’t enough to alter their blood sugar. 
In fact, only one study was able to show an increased risk of obesity in cats fed dry cat food, and there were other factors at play. The cats in this study were male, neutered, inactive – all risk factors for obesity in themselves. In fact, no other study to date has been able to show that dry cat food causes obesity or diabetes, even if common sense would suggest it should.
The benefits of dry cat food
The benefits of serving dry cat food are real:
There is a school of thought that dry food can help keep teeth clean, but I think it’s a stretch. Most kibble doesn’t have the rough texture that would be required to remove plaque from a tooth surface, and even if it did, a piece of kibble is unlikely to find its way around all of the tooth surfaces in a cat’s mouth. Moreover, most cats don’t really chew their food. It goes straight down the hatchet, missing the teeth entirely.
If you want to promote dental health, brush your cat’s teeth. If you want to use food that slows down plaque formation, consider products with a Veterinary Oral Health Council seal, or visit www.vohc.org for a list of VOHC Accepted Products.
What to do if you feed dry cat food
The main disadvantage of dry food is that it's dry. We'll get into this topic more in our discussion of wet food below. But if you feed dry cat food, you already know that your cat is not getting the hydration he needs from his food. You need to actively promote water intake:
- Make sure your cats have a constant supply of clean water.
- Keep water bowls separate from your cat’s food and litter boxes. Cats drink more water when everything is kept separate.
- Consider using ceramic or steel bowls, which many cats seem to prefer. It’s possible that a plastic bowl lends a flavor to the water that some cats don’t like.
- Offer multiple drinking stations, especially in multi-cat households so a cat can feel comfortable taking a sip without getting ambushed.
- Consider using a cat water fountain like this model by Veken, or this one by MOSPRO for cats who prefer running water. Clean them often and change the filter per the manufacturer’s recommendation.
- Try adding flavors to a cat’s drinking water to increase her interest: chicken broth or the water from a can of tuna, for example. Make sure neither contain garlic or onion, which can be harmful to cats.
Wet cat food
The main reason to feed wet cat food is that it’s wet. That sounds silly to say, but it’s true.
Our house cats are descendants of desert animals who evolved to live on as little water as possible. Desert cats get most of the moisture that they need from the juices in their prey, which probably has a water content of at least 60%. Because extra water wasn’t always available to them, cats’ bodies managed the lack of water by concentrating their urine. This was good for immediate survival but not necessarily good for a cat’s urinary system over the long term.
Cats no longer live in the desert and there is no need to put that kind of stress on their kidneys, but go tell them that. Cats are notoriously weird about drinking water. Read this blog post, Why won’t my cat drink out of her bowl? for more information about cats and their difficult relationship with drinking water.
The high moisture content of wet food can help compensate for a cat’s low thirst drive. Eating wet food can help prevent a cat from becoming dehydrated, which in turn can prevent problems like constipation.
But even more important, proper hydration is critical to cats with urinary tract problems, diabetes, and kidney disease. Minerals in a cat’s body tend to gather up into stones, which can cause inflammation or obstruction of the urinary system. The more water a cat has passing through his kidneys, bladder, and urinary system, the more the minerals, grit, and toxins get flushed out. More dilute urine means there is going to be a lower concentration of inflammatory compounds in a cat’s bladder overall.
It is unknown whether eating wet food can actually prevent some of these terrible diseases in the first place, but we know it can help a cat manage disease she may already have.
The other reasons to feed wet food
There are other reasons, besides wetness, to feed a cat wet food.
More protein and fat. In general, wet food tends to have more fat and protein and fewer carbohydrates than dry food, although this can depend upon the individual foods you’re comparing. We know that cats require up to 3 times the protein than omnivores require so this is a big deal.
The disadvantages of wet food
More expensive. For all the advantages, wet food isn’t the clear winner in the wet versus dry war. For one thing, it’s more expensive to feed. That is no small thing.
Spoils quickly. An opened can of wet cat food spoils quickly. Food in a dish should probably be tossed after two hours, although some experts claim that it might be safe for as long as four to six hours. Use your judgment – it’s probably not worth a sick cat to stretch the limits of food safety.
Blended or mixed feeding: the best of both worlds
Maybe you don’t have to pick a wet or dry side. Blended or mixed feeding allows you to take advantage of the benefits of both types of cat-food formulations.
Blended feeding means mixing wet food with dry food. A cat who has a little of both gets some of the advantages of added moisture and superior protein content of wet food, but allows a cat owner to “stretch” the more expensive food.
A mixed feeding would involve, for example, feeding dry food in the morning and wet at night. That way a cat can graze all day if she chooses. She’ll have some of the same of the advantages of a wet diet, and you can head off to work knowing that the dry cat food isn’t going to spoil while you’re away at work all day.
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