Dry vs. Wet Dog Foods: Which Is The Right Choice? Part 1
As pet parents, it’s important to get all the information we can about we should be feeding our dogs. After looking at all the dog food available on the market, it can be confusing as to which one to pick. And it’s not just about brands; it’s also about whether to go with dry kibble or wet food. So what’s the right answer? Sabine Contreras, Canine Care and Nutrition Consultant, weighs in with her expert advice in this three-part series.
Comparing Wet and Dry Foods Fairly
Pet owners today have a wide variety of commercially prepared foods to choose from. Unfortunately, over the years canned food has fallen out of favor and gained a rather negative reputation – for no good reason at all.
Before we examine various claims about the advantages and disadvantages of dry and wet food, I’d like to explain how to correctly and fairly compare the nutritional value of different types of foods:
Since percentages always express a relative content, we have to eliminate the weight of the moisture by looking at the “solid part” only. This is accomplished by converting all percentages to “dry matter basis” and mathematically removing the moisture.
As an example, we will look at a dry food with 10% moisture and a wet food with 78% moisture – average values for common products. If you know how much moisture a food contains, it is easy to determine the solid parts (the dry matter) by subtracting the moisture percentage from 100%: 90% and 22% respectively.
To determine the dry matter values for the various components like protein, fat, fiber, etc., we divide the given percentage by the amount of dry matter and multiply the result with 100. Here’s an example: 24% protein in a food with 90% dry matter will convert to (24% / 90) x 100 = 26.67%, 9% protein in a food with 22% dry matter to (9% / 22) x 100 = 40.91%.
As you see, while the wet food contains a higher amount of moisture, the solid part has a better nutrient concentration than the dry food. The main advantage of canned food is that even standard varieties that include some grains or other sources of starch, veggies, fruit and so on have a better concentration of protein and fat (the important parts in the diets of carnivorous animals like dogs) than dry food, which has a high content of carbohydrates.
Here are some actual numbers by weight to further illustrate:
90% dry matter in a food means that in one pound of dry food
- Approximately 14.43 ounces is the solid part
- Approximately 1.57 ounces is moisture,
- You would have to dehydrate 17.78 ounces of dry food to get one pound of dry matter
22% dry matter in a food means that in one pound of wet food
- Approximately 3.53 ounces is the solid part
- Approximately 12.47 ounces is moisture,
- You would have to dehydrate 72.8 ounces of wet food to get one pound of dry matter
Expressed in simpler terms, the dry food is just over four times as concentrated as the wet food.
Advantages and Disadvantages of Wet and Dry Foods
After looking at the comparison, you will probably ask: “why should I pay money for water in food when I can add that myself at almost no cost”? The answer is easy: the concentration of nutrients isn’t the only aspect to take into consideration, in fact in many cases it may even become a health problem.
Higher intake of (natural) moisture at mealtime
The amount of moisture in canned food is closer to the composition of what a dog or cat would naturally eat “in the wild” – whole prey. Their digestive process requires moisture on many different levels, for example protein is processed in the liver and any waste materials are filtered and excreted by the kidneys. The liver needs water to process protein and as a medium to carry waste products to the kidneys, where they are filtered out and most of the water is reabsorbed.
Pets who eat mostly canned food or a home prepared diet automatically take in more moisture than those eating kibble, so they do not need to compensate as much by drinking and excrete less concentrated urine. Contrary to what many people think and pet food companies claim, dogs (and cats even more so) do not instinctively know how much extra water they have to drink to make up for what is lacking in dry food.
A greater incidence of bladder diseases and stones/crystals in animals eating dry food is one result. An increasing number of American Veterinary Medical Association members, including board-certified veterinary nutritionists, are now strongly recommending the feeding of canned food only instead of dry kibble to cats, but the issue has not been officially addressed in dogs, since they have a somewhat better ability to compensate by drinking from their water bowl.
Fewer “empty” calories
Overweight pets also benefit from eating canned food, since unlike carbohydrates, water adds bulk without any extra “empty” calories (dogs and cats have no nutritional requirements for carbohydrates, but they do for protein and fat), making the pet feel full faster, without overeating.
It is important not to overfeed though, since canned food contains a comparatively higher amount of fat, which delivers over twice as many calories per weight unit as protein and carbohydrates. Where obesity and not just weight maintenance is a concern, you should choose lower fat varieties of wet food.
More ideal mineral contents and ratios
While nutrient-dense dry foods are certainly more economical and overall less expensive to feed, a highly concentrated diet is not always desirable. Especially minerals and trace elements are present in such high amounts in dry foods that pets can ingest 3-4 times and more the daily recommended allowance, which can become problematic in the long run.
Wet foods do not only have a more natural moisture content, they also do not supply highly excessive amounts of minerals like calcium, phosphorus or magnesium, and trace elements like iron, copper or iodine. The body only requires relatively small amounts of these to function properly and any excess must be filtered out and excreted.
Less processed nutrition
One of the most important advantages of wet food is that it is much less processed and often made from higher quality ingredients than dry kibble. Wet food requires no cooking prior to the canning process, since it is cooked in the can to create a bacteria free environment. Food being less processed means it is also more digestible, the body doesn’t need to work as hard to utilize it.
Unlike during the manufacturing of dry food, moisture does not have to be removed from the ingredients of canned food, so food ingredients like meat, grains, potatoes/sweet potatoes, pasta, vegetables and fruits remain fairly unchanged. Many ingredients used to manufacture dry food have already been processed at least once before they are mixed into kibble “dough” and cooked yet again (rendered meat meals and animal-based fats, dried vegetables and eggs etc.).
Beware though, some canned foods are made with rendered meat meals, and feeding these defeats our purpose. Check the label, it should list fresh meat only.
Longer shelf life, less additives and preservatives, no flavoring agents
Canned food generally has a shelf life of two years and more without degradation of nutritional value, compared to dry food, which can lose much of its nutrient content within a year of the manufacturing date – depending on how it is preserved and stored. The more natural stabilizers are used, the shorter the shelf life.
A 1997 study by the University of Illinois Department of Food Science and Human Nutrition found that canned fruits and vegetables for example provide as much dietary fiber and vitamins as the same corresponding fresh foods, and in some cases, even more. Fresh produce starts to lose vitamins as soon as it is picked, and often travels long ways before it ends up on store shelves.
Although small amounts of preservatives may be present in canned pet food if they were already added to specific ingredients used for the formulation, it does not need added preservatives since the canning process sterilizes and preserves the food in an oxygen-free environment.
There is plenty of meat and fat to make the food palatable without flavoring agents, and since the can is sealed no humectants are needed to keep moisture in, and no mold inhibitors (like in semi-moist food products) to prevent the food from becoming moldy.
Sabine Contreras is a Canine Care and Nutrition Consultant based out of Los Angeles, California. She specializes in natural, preventive dog care as well as canine nutrition and offers personalized feeding plans for dogs of all sizes, breeds and ages, no matter if they are companions, performance, working or show dogs. She shares her home with a husband, Jack Russell Terrier and five cats.