There are many varieties of commercial pet food to choose from.
Most store-bought food comes in either a dry form (also known as kibble), semi-moist
or a wet canned form. Dry food contains 6-10% moisture by volume, as compared to
60-90% in canned food. Semi-moist foods have a moisture content of 25-35%.
Pet owners often prefer dry food for reasons of convenience and price. Dry food
can be left out for long periods of time to allow your pets to ‘graze’ but some owners
portion control and feed their pets fresh food twice a day, as they would with wet
Many dry foods can be less expensive, per pound, than their canned (wet) or semi-moist
counterparts, and do not spoil as quickly as wet food can. In addition, dry food
is more nutritionally dense than canned food because of the canned food's high moisture
content. This means that more canned food must be fed to meet the animal’s requirements,
compared to dry. However, dry food generally contains a higher percentage of fillers
such as corn and wheat. Generally, less expensive dry dog and cat foods have more
fillers and less meat. Excess carbohydrate consumption such as corn and wheat can
cause GI tract problems and shorten the life span of your pet. It is always important
to note the ingredients in the pet food you choose (even if it is vet recommended!).
Wet or canned food is significantly higher in moisture than dry or semi-moist food.
Because the food is sterilized after being canned (sometimes it is also cooked in
the can), it is often easier to ensure the sterility of wet food. A given wet food
will often be higher in protein or fat when compared to a similar kibble on a dry
matter basis (a measure which ignores moisture), however, given the canned food's
high moisture content, a larger amount of canned food must be fed than with dry food.
Grain gluten and other protein gels may be used in wet food to create artificial
meaty chunks, which look like real meat.
Dry vs Wet Food
In dogs, dry food has a significant effect on dental health over wet food. The chewing
required for dry food helps to keep teeth clean and ‘bad breath’ cases are drastically
reduced in dogs that eat only dry food compared with those on a wet food diet.
In cats, studies have not shown any difference between a dry or wet food diet for
dental health. Cats generally do not 'chew' their food and usually only crunch once
or twice before it is swallowed. Cats also lack the enzymes that humans possess inside
their mouths to help breakdown the food they eat.
There are foods specially formulated for animals allergic to common ingredients such
as chicken, wheat, or corn. These foods usually contain ‘novel proteins’ and substitute
uncommon starches for the usual grains. Meats used in allergy formulas can range
from the mundane, such as lamb, beef, or whitefish, to the unusual, such as venison
or duck. Carbohydrates in allergy formulas are usually a less common grain, such
as rice or barley, but such ingredients as potato and quinoa are sometimes used.
The commercial approach to allergies in animals is not the same as the veterinary
Prescription diets, purchased from a veterinarian, will often contain common ingredients
that have been hydrolyzed to prevent them from triggering an immune response.
Some foods are designed for pets with maladies, such as urinary tract infections,
and some are tailored to the dietary needs of especially young or aging animals.
There are also vegetarian foods, for owners who do not want their pets to consume
meat products, as well as for dogs or cats who have experienced allergic reactions
to a number of animal-based ingredients.