BUT IS MIXING DRY AND WET FOOD BAD FOR DOGS AND CATS?
I often have dog and cat owners come into my clinic and tell me: “Doctor, I can’t mix kibble with wet food because it’s bad for my pet’s digestion.” … Before answering this question, let’s clarify the basics of pet food technology and how dry and wet pet foods are made.
Put simply, wet foods are made from products that undergo less complex processing; the raw ingredients are more or less processed, canned, and sterilized. With around 70% moisture
To make kibble, the finely ground and homogenized product is passed through an extruder, a machine that uses high pressure and temperature to create a very fluid mixture (similar to a mousse), which is then cut into small pieces. These still-soft pieces are then dried so they become hard and form kibble, ready to be packaged. With 8-10% moisture
We can therefore say that a substantial difference between wet and dry food is the percentage of water they contain. It should be noted, however, that the production process for kibble necessarily requires a carbohydrate source (usually starches), unlike wet food.
BUT HOW DOES DIGESTION WORK IN DOGS AND CATS?
Once they reach the intestine, primary nutrients (meat, sugars, and fats) are broken down into simple molecules (proteins, carbohydrates, and lipids), and then into even simpler molecules. This happens with all food components, whether dry or wet.
For example, consider how carbohydrates in foods as different as rice and pasta are still broken down through digestion into the same glucose molecules. The same applies to protein sources, which, for instance, will ultimately be converted into amino acids, whether they come from lamb, chicken, or tuna.
Therefore, the digestive process will take longer for more complex foods, but regardless of how complex a food is to begin with, digestion in the intestine will always break it down into the same simple molecules so they can be absorbed.
SO, WHAT HAPPENS DIGESTIVELY WHEN I MIX DRY AND WET FOODS?
As mentioned earlier, there is a significant difference in water content between dry and wet foods. Water is an essential nutrient, but it does not cause substantial changes in digestion, except in the speed of gastric transit. The higher the moisture content, the faster food passes from the stomach to the intestines.
In healthy animals, faster or slower passage through the stomach does not cause problems, so the intestines will receive the wet foods first and then the kibble. Generally speaking, wet foods contain fewer ingredients than dry foods, so not only do they pass through the stomach faster, but they are also digested faster.
SCIENTIFIC EVIDENCE: WHAT DOES IT SAY ABOUT A MIXED DIET?
Animals enjoy both dry and soft foods. Cats usually prefer them in separate meals throughout the day, unlike dogs, which enjoy them together in the same meal. A mixed diet, therefore, is not to be discouraged; on the contrary, it combines the benefits of both.
Dry foods also promote better oral hygiene. Several studies show that their mechanical action limits plaque buildup. Wet food, on the other hand, is often more palatable and increases water intake, which is especially useful for cats.
BUT FINALLY, WATCH THE CALORIES!
I always point out, though, that when feeding a mixed dry and wet diet, we need to consider the total calories we are providing. And while it’s easy to work out the daily amount to feed for one type of food, since it’s listed on the packaging, it’s less easy if I want to feed two different foods. For this calculation, ask your veterinary nutritionist for help. Maybe I’ll share a few “tricks” soon on how to do quick, simple calculations to get the calories right if you want to combine dry and wet food.
Dr. Simone Falci
Veterinarian specializing in nutrition
BIBLIOGRAPHICAL REFERENCES
*Ingham et al. 2002
**Burger et al. 1980