Browsing the web you will find articles and interventions (often unsigned and always without scientific bibliography) that demonize the act of mixing a wet food with a dry food for our furry friends. But why? Is it really a harmful practice?

 

The answer is no! But let’s try to go by points and understand why.

  • The water concentrations are different:
    True … So what?

Each composite dish is necessarily, when it is not commercial food, made up of foods with different concentrations of water inside. A nice soup with croutons, for example, will be made from an almost dehydrated part (croutons) and a very moist part (soup) mixed together.
Do you eat it? Do you consider it harmful? I would say no… so why say it’s bad for a dog’s digestive health?

 

  • The digestion times of dry foods are different, usually longer, than wet ones:
    True … And with that?

When digestion begins, the bolus (i.e. the mixing of chewed food) begins to be attacked by digestive juices: first the gastric, then bile, pancreatic juice, enteric etc. In this process of “descent” the different parts will be attacked in the usual way but, given the presence or absence of water and the characteristics of the substrate, broken down at different times.
This will create a progression, a gradualness from the most digestible (at the top) to the slowest (last in the row). In short, what will be “drier” will take longer than what is wetter on the way to expulsion.
Does this seem like a problem to you? If anything , it is an advantage … a better distribution, a greater stratification of substances and a gradual, constant transit along the internal roads.

 

  • There are studies that show this is incorrect:
    For real? And what are they?

Indeed, there are publications that indicate the exact opposite . There are researches that evaluate the transit times of foods of all kinds. These studies often contemplate the possibility of association between substances of different digestion times 1 and, in no case, did this cause a problem. There are also researches ² that have evaluated the mixture of “croquettes of different sizes” because, also in this case, the digestion times are different due to the thickness and volume (smaller, more attackable, previously digestible).
Here, too, our friend’s health has been considered more than safe… the concept explained above is valid. Finally, as a final clarification, it is necessary to consider that digestion times vary from individual to individual ³ : therefore it is even more difficult to standardize a model, let alone a danger rule.

In summary, what I would recommend is always a little attention to what you read online anyway. The Internet is the forge of ideas… but science is a little more organized. And then the advice is always to contact your trusted veterinarian for certain specific doubts : better if 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/