Most dog food comes in bags (dry) or cans (wet), but you can also find frozen and semi-moist foods. Each has advantages and disadvantages. The choice you make depends on your pug's nutritional needs, whether he likes the taste of the food (palatability), your own desires regarding convenience and quality, and your budget.

Canned Food

Dogs love canned food. It gets that good flavor from its high fat content. For old pugs that have lost teeth, canned food is easy to eat. It's also easy to serve; just plop it into a bowl.

The disadvantages are several. For one, canned food is expensive. Its water content is high — as much as 78 percent — so you're not getting a lot of meat for your money. Canned food sticks to teeth and is a factor in the formation of plaque, which leads to periodontal disease. Although canned food has a long shelf life while it's still in the can, it must be refrigerated after it's opened, and it can't be left in your pug's bowl for long periods without spoiling.

Dry Food

Pricewise, dry food has it all over canned food. It costs much less, which is something to consider if you're on a budget or feeding more than one pug. Dry food has a long shelf life and won't go bad if it sits in your pug's bowl all day (not likely unless he doesn't like the taste). Don't forget to choose a small kibble size for your pug's eating comfort.

Dry food has a reputation for helping to prevent the buildup of plaque and tartar on teeth, although it's not as beneficial as you might think. Dry foods and dog biscuits can help chip off small amounts of tartar (the hardened form of plaque), but they don't affect the gum line area, where the real problems start. The exception to this is veterinary foods that are designed to have a cross-hatch effect on teeth, scrubbing them all the way to the gum line.

On the downside, kibble usually contains less fat and more carbohydrates than canned food, so it doesn't taste as good. If you have one of the rare finicky pugs, you can tempt his taste buds by mixing a little canned food in with the dry food.

Frozen Food

Frozen dog foods are made with fresh ingredients and contain no artificial preservatives. They're mixed, formed into loaves, rolls, or cubes, and flash-frozen to preserve freshness. Consider a commercial frozen food if you like the idea of fresh ingredients but don't have time to cook for the dog yourself.

The disadvantage is that frozen dog food is available only in limited distribution. You're more likely to find it at mom-and-pop pet supply stores rather than at big pet supply chains. It must be kept frozen until you're ready to use it, and you have to remember to defrost it before feeding. While cubes can be fed frozen, it's unlikely that this sort of cold meal would appeal to your pug. Any unused portion must be refrigerated. If you're traveling with your pug, it's difficult to bring frozen food along unless you have some means of refrigeration or of finding it in pet supply stores along the way. Check the manufacturer's Web site before you leave so you can note the addresses and phone numbers of stores that carry the food.

Semi-Moist Food

This type of diet is softer than dry food but not as messy as canned food. The amount of water it contains ranges from 15 percent to 30 percent. Ingredients include fresh or frozen animal tissues, grains, fats, and sugars.

Other than convenience and palatability, there's not much to be said in favor of semi-moist foods. They contain high amounts of sugar, putting them squarely in the junk food category. In cost, they fall somewhere between canned and dry food, although single-serve packets usually compare in price to canned foods. This type of food is best given in small quantities as a treat.

Premium Foods

Some dog foods are described as “premium.” This term, which is not regulated by law, generally refers to products that contain highly digestible ingredients with good to excellent availability of nutrients. The difference between premium and nonpremium foods is density per volume. That is, a cup of a premium food usually has more usable nutrients than a cup of nonpremium food. You can see the difference in the amount of poop your pug produces. In the long run, it can cost less to feed a premium food because your pug eats less of it and gets more out of it.