Browsing the web, you’ll find articles and posts (often unsigned and always without scientific references) that demonize mixing wet food with dry food for our furry friends. But why?Is it really a harmful practice?
The answer is no!But let’s break it down and understand why.
- Water concentrations are different:
True… So what?
Any homemade (not commercial) composite dish is necessarily made up of foods with different water concentrations. A nice soup with croutons, for example, is made up of a nearly dehydrated part (the croutons) and a very moist part (the soup) mixed together.
Do you eat it? Do you consider it harmful? I’d say definitely not… so why would people say it’s bad for a dog’s digestive health?
- The digestion times of dry foods are different, usually longer, than those of wet foods:
True… So what does that mean?
When digestion begins, the bolus (the mixture of chewed food) starts to be broken down by digestive juices: first gastric juices, then bile, pancreatic juice, intestinal juice, etc. In this “downward” process, the different components will be processed as usual, but—due to the presence or absence of water and the substrate’s characteristics—they are broken down at different times.
This creates a progression, a gradual flow from the most digestible (at the start) to the slowest (at the end of the line). In short, the more “dry” parts take longer than the more moist ones in the process leading to elimination.
Does this seem like a problem? If anything, it’s an advantage… better distribution, greater stratification of nutrients, and a gradual, steady transit through the digestive tract.
- Are there studies that show this is an incorrect practice:
Really? Which ones?
In reality, there are publications that say the exact oppositeThere are studies that assess transit times for all types of foods. These studies often consider the possibility of combining substances with different digestion times¹, and in no case did this cause any issues. There are also studies² that assessed mixing “different-sized kibbles” because, in this case too, digestion times differ due to thickness and volume (smaller pieces are easier to break down and digest earlier).
Here too, our pet’s health was found to be more than safe… the same logic applies as explained before. Finally, as a last note, it’s important to consider that digestion times vary from individual to individual³: so it’s even harder to standardize a model, let alone a rule claiming it’s dangerous.
In summary, what I would recommend is still to always be a bit careful about what you read online. The internet is a breeding ground for ideas… but science is a bit more structured. And so the best advice is always to turn to your trusted veterinarian for specific doubts, preferably one specialized in nutrition.
Oscar Pellegrini
DVM – PhD Animal Nutrition, University of Pisa
Bibliography
1. https://link.springer.com/article/10.1007/s00360-012-0727-y
2. https://pubmed.ncbi.nlm.nih.gov/29030884/
3. https://pubmed.ncbi.nlm.nih.gov/29031328/