Pet Food Part IV: Guaranteed Analysis, Homemade Diets & Thanksgiving

As the final topic in our series on pet food labels, we’ll address perhaps the least exciting but most confusing aspect of the food label: the guaranteed analysis.

“Guaranteed Analysis” is the pet food industry’s equivalent of the Nutritional Facts box we are so used to seeing on our own products. The four main ingredients listed are crude protein, fat, fiber, and moisture. Many cat foods will also list the maximum percentage of the mineral component “ash,” as well as taurine and magnesium, and some dog foods will also list various electrolytes.

Guaranteed analyses are listed on an “AS FED” basis, meaning the actual amount in the product. This is not that relevant when comparing one dry food to another dry food; however, when comparing a dry food to a canned food there will be significant differences in any of these levels due to the moisture difference.

For example, the percentage protein on a canned diet may be 12 percent, but on a dry food basis is 29 percent. Initially, it seems that the dry food has more protein; however, once the 75 percent moisture of the canned food it taken into account it is clear that the canned food actually has higher protein levels. To best compare levels of nutrients, it is necessary to convert to “DRY MATTER BASIS,” meaning that all the moisture in the diet is taken into consideration.

In simplified terms, most dry foods have 10 percent moisture (90 percent dry matter), and most canned foods have 75 percent moisture (25 percent dry matter).  In order to determine the amount of protein/fat/etc. on a dry matter basis, divide the amount of nutrient  by the amount of dry matter (i.e. label shows a guaranteed analysis of 25 percent protein and 10 percent moisture (90 percent dry matter), meaning the actual dry matter protein is 0.25/0.9 = 28 percent protein; versus a canned food label showing 10 percent protein and 75 percent moisture, which would be 0.1/0.25 = 40 percent protein.

But, rather than straining your brain with a lot of math while you’re perusing the overwhelming number of foods at the pet store, just remember that the amount of dry matter in dry foods is about four times that in canned foods. So, you can easily compare the dry matter between foods by multiplying the canned food values by four.

In addition to the guaranteed analysis, “as fed” and “dry matter basis” come into play in the ingredient list as well, which we touched on in an earlier post. Ingredients are listed by weight. However, moisture can make a significant difference in the weight of a particular ingredient. For example, as the FDA website points out:

“For example, one pet food may list ‘meat’ as its first ingredient and ‘corn’ as the second ingredient. The manufacturer doesn’t hesitate to point out that its competitor lists ‘corn’ first (‘meat meal’ is second), suggesting the competitor’s product has less animal-source protein than its own. However, meat is very high in moisture (approximately 75 percent water). On the other hand, water and fat are removed from meat meal, so it is only 10 percent moisture (what’s left is mostly protein and minerals). If we could compare both products on a dry matter basis (mathematically ‘remove’ the water from both ingredients), one could see that the second product had more animal-source protein from meat meal than the first product had from meat, even though the ingredient list suggests otherwise.”

Thus, it is important to take into account not only percentages but the formulation of the diet when comparing labels and evaluating the ingredient list.

When it comes to pet foods, we have to address feeding human food as food labels, guaranteed analysis, etc. all kind of get thrown out the window. We don’t recommend ‘winging it’ with your pet’s nutrition — they’re truly not small humans. If you’re wanting to cook your pet a diet, we strongly recommend working with a veterinary nutritionist (such as the nutrition service provided by the veterinary teaching hospital at Virginia Tech or BalanceIT) to make sure it is balanced and complete and that any illness or disease process is being considered in the diet as well.

Along the lines of human food, feeding table scraps are a good way to end up with a fat pet and also can increase their risk of GI upset. As we approach Thanksgiving, it is very common to see an increase in cases of pancreatitis (inflammation of the pancreas) as holidays tend to be a time when pets are especially likely to be getting extra treats from family members and visitors and also more likely to get into stuff when we’re distracted.

Most human food is too rich or too high in fat for most pets. We strongly recommend being strict with the table scraps, keeping food away from counter-surfing canines (and felines too!) and trash cans inaccessible to the rummaging furry family — which will lead to a happier and healthier holiday for all!