What is the purpose of wet cat food?

Question

What's the purpose/value of a wet food diet for cats? Why would you want to do that?

Due to some recent health issues I've been highly focused on my cats diet, and regularly logging caloric/potassium/B₁₂ intake as well as mass eaten per meal. One thing I noticed is that wet food has an extremely low calorie to mass ratio compared to dry food.

It seems nearly impossible to meet a cat's caloric intake requirements on wet food alone. For example, a 5.3 oz can of a certain brand of wet food contains only 62 kcal, meaning that a cat would have to eat a whopping 18-20 or so ounces of this stuff to get their daily intake in the 200 kcal area.

The four wet foods I have info on here range from 0.735 to 1.245 kcal/g, meaning 160-272g of food that must be consumed per day. That's on or past the upper limit of what I see healthy cats fit in their stomachs in one day (my 3 year old tops out around 200g if she absolutely stuffs herself, but typically eats 180g-190g, my older cat maxes out about 180g, but typically eats 150g-160g). By comparison, the dry food I have on hand is 4.103 kcal/g, meaning only 48g or so must be eaten.

Under the assumption that the nutritional content of wet vs dry food is similar and sufficient, I can't imagine a normal cat being able to eat enough wet food to get even close to their daily caloric intake. Both of my cats only get a disturbingly low 130-180 kcal/day when on wet food only.

So why does wet food exist? For what purpose would you feed your cat wet food? I used to view it as a reasonable alternative to dry food but since I began calorie counting and monitoring diets I can't see a reason to ever feed it to a cat.

The only value I can sort of see in it is if you want to do a wet/dry mix to maintain a healthy caloric intake but also add some mass to the food so the cats aren't walking around on empty stomachs, but I'm not sure if there's any real reason to do that. The other thing is, I wonder if I'm just selecting particularly low calorie wet foods (there seems to be a trend of lower-end cat foods containing higher calorie counts).

The brands I've examined are Royal Canin, Hill's, Wellness, Iams ProHealth, and various small but respectable brands. Currently I've settled on Royal Canin for both wet and dry.

^{(I don't buy the "wet foods help cats get water" line of reasoning so much. While they'll certainly get water from wet food, in my limited personal experience, in a sample of about 20 or so cats, I've never actually seen a normal, healthy cat severely dehydrate itself when water is available by not drinking it, and a pet fountain or better placement of a water bowl almost always solves issues there. When a cat isn't drinking water it's seems to virtually always be a sign of an actual bigger health issue. But, in any case, I'm interested in other value besides just water content, and I can't justify watery food with critically low caloric intake.)}

Answer 1

While probably not an exhaustive list of reasons here's some I know of:

Bonding

As @littlemisskitty states there can be significant bonding benefits to the whole process of "food time", my two both certainly know what it means when I say the magic words! And seeing them seemingly enjoy it does give me a nice warm and fuzzy feeling. Closely related to..

Enjoyment

As much as you can ever be sure of these things both of mine seem to "enjoy" their wet food more than the dry and generally we'd all like our pets to be living a happy life, right?

Variety in Diet

Most cats will seek out variety in their diet, and a mixture of wet food plus dry kibble for grazing automatically provides part of that and mixing up the flavours of the wet food helps introduce more while still allowing you to keep them on the one variety of kibble

Monitoring intake

While your mileage may vary I know with my two that wet food is eaten relatively quickly and in one "sitting" whereas the kibble is grazed at through the day and if you have multiple cats then the grazing behaviour makes it hard to know who has eaten what and when.

Water

I know you weren't keen on this reason but (and I appreciate it varies from cat to to cat) but many cats aren't great at drinking enough water. Many breeds do have quite a low thirst drive as their food sources in the wild (birds, small rodents etc) contain a high water content which they then supplement with occasional drinks of actual water. As you point out it's very rare for them to severely dehydrate themselves where water is available (barring another medical or behavioural condition of course) but as with humans they should really be drinking before they get too thirsty and while this is unlikely to cause immediate issues it can have implications for kidney function in later life and can also contribute to causing UTIs.

A quick side note on the calorie counts in wet food - I wonder if the cheaper brands you looked at were bulking that calorie content out with cereals as it is a cheaper way than adding meat. Cereals/Grains aren't really harmful to your cat per se (unless it has allergies or other digestive issues) but they don't digest them that well and really as obligate-carnivores they should only really be making up 10-20% of their calorie intake that way with the vast majority coming from meat.

Answer 2

Another reason nobody has mentioned (yet): if your cat gets chronic kidney disease (CKD) later in life, it becomes essential to get as much liquid into them as possible and wet food is highly preferable (dry is contraindicated unless they really won't eat anything else).

I fed my previous cat exclusively on dry food until he developed CKD at 14 years old, at which point it was a real problem teaching him (a) that wet food really was food; and (b) how to eat it tidily. (I needed to sponge down the wall by his feeding station regularly, as he'd taste it then shake his head to dislodge the odd stuff in his mouth). (Wet food is also better for elderly cats with dental problems, I've found).

We got there in the end, and he lived to almost 20; however, his successors are getting fed a mixed diet of wet and dry food -- I work on the rule of thumb that 85g wet = 17g dry, so they get 85g wet and 34g dry every day (they're hefty cats, so 50g/day of dry food is about right). As an added bonus they adore the wet food, and pester me for it in the morning. Once they've polished off the wet food, they get their ration of dry food to free-feed on all day.

Answer 3

Wet food has a lot more water, and a lot less carbohydrates. If kitty loves kibble she may not be willing to eat enough wet to keep her weight up. I tend to feed a combination of canned wet food and raw muscle meat. On a pure meat diet most cats will self regulate to a healthy weight. That might look like kitty is to thin if you have only had obese cats. Carbs pack weight on because cats can’t use carbohydrates effectively and eat more to make up for insufficient protein.

Raw meat tends to have more calories, and it also has more useable calories. The feeding recommendations of 200 to 300 calories is adjusted for the insufficient protein in kibble. Raw meat has higher calorie density to both kibble and canned food. Beef has more calories than chicken. Lamb has more calories than beef. Some cats like ground meat, some like mouse sized chunks, and some like bone in whole meat. (Chicken wings and legs are good. Don’t cook it. Raw bones are safe, cooked bones splinter) Eggs are also calorie dense if kitty will eat them. If you feed only raw, get Oasis or wild trax supliments. Slab meat does not have enough calcium or taurine, and needs suplimentation..Whole prey killed prey (guts and all) fills all dietary needs. (But mouse in the quantity needed for a cat is expensive.

Answer 4

Variation in Calorie Density

Wet food has a pretty wide variation in calorie density (how many calories are in a given 5.5 oz can of food). The cat food nutrition chart assembled by Lisa A. Pierson, DVM shows foods from 50-250 kcal per 5.5 oz can (note that this chart hasn't been updated in 5 years; I just include it too show a range of calorie densities).

So, if you need your cat to gain weight and your cat consistently eats the same volume of food each day, you can switch to a more calorically dense food. If you need your cat to lose weight, you can switch to a less calorically dense food.

Also, in sorting the above list by calorie density, I don't see any association between cheap/expensive foods.

Wet Food Doesn't Require Carbohydrates for Manufacturing

To get dry food to hold its shape when dried, it needs to contain carbohydrates. Even dry food labeled "grain-free" will contain carbohydrates (potatoes and peas are often used).

Cats cannot digest much plant matter, so many people try to avoid feeding food high in carbohydrates.

While there are wet foods with high carbohydrate percentages, you can find wet foods with lower carbohydrates than any dry food available (even at the grocery store). For example, the lowest carbohydrate dry food I'm aware of is Evo (13%). Looking at the (old) chart I linked above, many Fancy Feast varieties are in in the 0-5% (dry matter) range for carbohydrate content.

The Water Question

Cats don't have much of a natural thirst drive and instead have evolved to get much of the moisture that they need instead from their prey. According to Lisa A. Pierson, DVM:

A cat's normal prey is ~70% water. Canned food is ~78% water. Dry food is ~5-10% water. Cats have a low thirst drive and they do not make up the deficit at the water bowl. They are designed to get water with their food.

Cats on canned food have been shown to consume at least double the amount of total water when compared to dry food-fed cats when all sources of water (food and water bowl) are considered.

There's also a supporting study - Effect of dietary water intake on urinary output, specific gravity and relative supersaturation for calcium oxalate and struvite in the cat. Catherine M. F. Buckleya, Amanda Hawthornea, Alison Colyera and Abigail E. Stevensona. British Journal of Nutrition / Volume 106 / Supplement S1 / October 2011, pp S128-S130

My personal experience agrees with these statements. We generally feed wet food, but have some dry food on hand (my husband likes to put a big pile of dry food out at night so we can sleep in without the hungry cat alarm). We would occasionally run out of wet food and just feed dry for a few days until we got to the store.

Once we got Romeo, we had to change this habit. If he ate about 3 days of dry food, he would get dehydrated and get a block in his urinary tract. A blocked urinary tract is a VERY EXPENSIVE EMERGENCY. If the vet does not treat a blocked cat immediately, the cat's bladder can rupture and the cat can die.

When we fed a combination of wet and dry, he had frequent urinary problems. Switching to dry for a few days nearly killed him. He's now allowed dry only on Friday nights, and he hasn't had any problems since then.

Answer 5

Personally I offer dry food for both of my cats throughout the day and they certainly do take advantage of it eating it off and on as needed. The wet food I feed one can cut in half twice a day (basically a can a day). I do it so they have breakfast with me and dinner with me. I use it as a snack treat. They simply love it. They are always so excited to see me collect the dishes we use for it and get the spoons together and the two cans of cat food. They watch me as I heat up my water for my oatmeal then put it together knowing their treats are coming. (They also hang out in the kitchen while I cook dinner for the family knowing when I finish and serve everyone, I also serve them). They have memorized their dishes as they are each different and I sit and eat my oatmeal while the two cats eat their half can of cat food. So I personally do not use it as calorie intake or for nutritional value but instead as a bonding and treat opportunity.

Answer 6

I really can't believe anyone would question wet cat food... that calorie count you make is kind of erroneous. People are using numbers of what really active barn cats used to be in the day... you must have some heavy cats. Indoor cats barely move and wouldn't need anywhere near the calories you're talking about. Mine eats less than yours and already has a pooch...

Also, cats survived on raw, wet, dead animal meat for millenias. They are also obligate carnivores, which means their diet should be ALL meat. They can't digest plant matter, grains, etc. Dry foods is more potatoes, corn and wheat than the actual nutrients they require.

Quoted text: Dry Food

“The biggest mistake people make is feeding cats dry food,” says Lisa A. Pierson, DVM, a California veterinarian focused on feline medicine and nutrition, and creator of CatInfo.org.

As it turns out, today’s domestic tabby evolved from desert-dwelling ancestors, a heritage that no doubt left our furry felines with their grace, hunting prowess -- and low thirst drive.

“We know that a cat’s sensitivity to thirst is blunted compared to a dog,” Case says. “They don't voluntarily drink water like a dog would.” And because cats naturally produce highly concentrated urine “we're setting them up for urinary tract problems when their diet is low in liquids.”

It isn't even about the water, although that does significantly impact it. Cats require a lot of taurine, which, guess what... is found in high abundance in chicken liver, not in the potatoes, corn and berries often being abundant in dry cat food.

Dry cat food just starves your cat while making it fat. Its like arguing why humans don't eat ice cream all day instead. That's super high calories. Must be healthy to eat only that... everyday. Or asking why humans don't eat burgers a day. You only need one to reach your calorie count.

I'm sorry, but I really wonder why you have cats if you ask this sort of question.

Answer 7

The point of wet cat food seems quite obvious: cats are evolved to get primarily from their prey, and wet food mimics that. Given that kidney failure is a leading cause of death for indoor cats, proper hydration is obviously essential to their long-term health.

If their food is 80% water by weight, then even if all the other ingredients were the same, it would have 20% of the calories per weight as dry food, which roughly matches the numbers you cite. But dry food does have more calorie-dense carbohydrates as a binder, which wet food doesn't need.

Also, you are vastly overestimating the caloric needs of a typical housecat, as do many owners based on how many indoor cats are dangerously overweight.

Answer 8

cats like to eat wet food because of the moisture.My gray adult cat Grace used to eat wet food,but when i switched to dry food she would not touch it.So i feed her a mix of wet and dry now,so she will eat both types of food.