Particularly with dogs, this seems to be something that comes up often in their care. When giving the animal "dry" dog food, is there anything beyond the animal's individual preferences that should dictate whether a small amount of water should be added to the food?
Are there any health conditions that would preclude giving the dog just the dry food if he/she likes it that way?
Dry dog and cat food should not be wet down if it is not going to be eaten in one sitting.
Moistened dry dog and cat food breeds bacteria. Part of the process that preserves the food for a longer shelf life is the dehydration.
Moistened dry dog or cat food should be left out and treated as if leaving out wet dog or cat food. It should be picked up and discarded, when you would normally consider wet food has been out too long to be healthy.
It doesn't need to be treated as if it is toxic after half an hour, by no means, it can sit there, but not for same the prolonged period that unmoistened dry food can be left out.
- Promptly refrigerate or discard unused, leftover wet pet food and containers (e.g., cans, pouches).
- Refrigerating foods quickly prevents the growth of most harmful bacteria. Refrigerators should be set at 40 degrees F. The accuracy of the setting should be checked occasionally with a refrigerator thermometer. (1)
Makers of dry dog food also advise this:
- Dry foods remain fresh over many months because bacteria can't grow and spoil food when moisture levels are low.
- Dry food packaging and the fatty coating of biscuits help prevent the entry of moisture and oxygen that can cause food spoilage during storage.
- Once opened, store dry foods covered in a cool dry place. Do not store moistened dry foods as moulds may grow, which can harm your pet. Purina
Another issue, which was discussed by @Baarn is that a dog (or cat) eating dry food will need to drink more water to counteract the dehydration processing of the food. The dry food is formulated with salt in a way to increase the pet's thirst, so they will crave more water, when eating dry food. If the dry food is wet down with water, this water contributes to the water needed to counterbalance the water needs of the pet. Any healthy pet will make up for this needed fluid b drinking.
It's always important to have an ample supply of fresh water for your dog or cat, especially when feeding with dry food, unless a qualified Veterinarian, who has examined your pet advises you not to do so.
Sources:
Veterinary Science Animal Husbandry
American Veterinarian Medical Association PDF
Centers for Disease Control and Prevention USA
cdc.gov (1)
Our vet told us that it is preferable to wet the dry dog food shortly before feeding it to the dog. There are two main reasons for it.
Most dogs don't drink enough
While some dogs drink a lot of water on their own, there are other dogs that are quite uninterested in their water bowl. If you fill the dogs food bowl with water, you can make him drink more. Some of the food will dissolve in the water and make it taste better, which motivates the dog to drink everything. (Don't force them to drink too much water though, see my second point)
We currently don't feed any dry food to our dogs, yet we still fill their bowl with water to make them drink.
Dry food can be dangerous
While this isn't true for every dry food, especially large dogs are at risk when eating a lot of dry food. Too much dry food at once may cause gastric dilatation volvulus.
Some of the more widely acknowledged factors for developing bloat include increased age, breed, having a deep and narrow chest, stress, eating foods such as kibble that expand in the stomach, overfeeding, too much water consumption in a small period of time;
So if you are feeding dry food, it can be good to let the food pre-soak a bit before feeding as this leads to the food expand in the bowl rather than in the dogs stomach. The safe amount of water depends on the dogs size. Some dogs will stop drinking before it gets critical, but others wont. It might be best to ask your vet about this.
Don't dogs need to chew?
The only concern I've heard regarding this, is that the wet food lacks hardness and offers the dog nothing to chew on. However, this concern does not come up with people who feed their dog wet food. Some large dogs even don't really chew on their dry food, they just swallow it whole.
I doubt that the resistance offered by dry foods is a challenge for the strength of any dogs jaw. If you want to train your dogs ability to chew, you might want to consider giving tooth cleaning treats once in a while.
