All Pets Veterinary Clinic
CHOOSING A PET FOOD
Understanding the Information on the Label
There are thousands of different pet foods available on the market today. If you are
like the typical dog or cat owner, you have probably stood in front of a huge wall of
pet foods at the store and wondered what one would be the best for your pet. This article,
will focus on understanding what information is contained on the pet food label and how
it is generally very deceptive when it comes to telling you what is contained inside the
food, the roles of several nutrients found in pet foods as well as their recommended levels
for cats and dogs.
Guaranteed analysis. The guaranteed analysis is the part of the label that many
people first examine to try to determine how much "nutrition" is in a specific type of
food. This section of a pet food label will generally list a minimum percentage value
for protein and fat and a maximum percentage value for fiber, moisture, and ash. Many
people will choose a food based on the information that appears in this section, which
as we will see can be a major mistake. This section of the label can be very misleading
for two reasons.
First of all, it can be misleading because it will only tell you a minimum or a maximum.
You have essentially no idea how much of the specific item is included in the food.
You simply know that it is not lower than the minimum or higher than the maximum percent
listed on the bag or can. For example, if you thought your dog was getting a little too
heavy and wanted a low fat food, you might choose one that said crude fat (min.) 2%. You
would assume that this food is a low fat food. However, all this information tells you
is that there is at least 2% fat in the food. It does not distinguish if there is 2% fat
or 40% fat. And, it would be perfectly legitimate if the food did contain 40% fat because
it only guaranteed that there was not less than 2% fat in the food.
Secondly, the guaranteed analysis can be misleading because it does not take into account
the quality of the nutrients listed. For example, a food may list minimum crude protein
at 25%. This does not tell us anything about the quality of the protein. It is very
possible that a large amount of the protein present may not be able to be digested by
the animal and used for energy. For what appears to be a fair level of protein, it is
possible that much of it will not even be able to be used by the animal.
List of ingredients. Another common part examined on the label of the pet food
is a list of ingredients. It is required for the list to be ordered from greatest to
least by weight. For example, if the list has chicken before beef, there is a greater
amount of chicken, by weight, than beef in the food. This can also be misleading.
Consider that an item, such as wheat, may be split into different forms of wheat on the
label. For example, wheat flour and ground whole wheat may both be listed on the list
of ingredients. Now, if chicken were listed first on the list, followed by wheat flour
and ground whole wheat, one would assume that there were more chicken in the product than
wheat. However, this can be a false assumption. There may be more chicken than wheat
flour and more chicken than ground whole wheat, but it is possible that the sum of the
two (and sometimes more than two) forms of wheat can be greater than the total amount of
chicken, by weight. Thus the food could have more wheat products than chicken even though
the label listed chicken first.
Moisture. Water will generally account for 8-12% of a dry food and 78-82% of a
canned food, with semi-moist foods being somewhere between the two. The guaranteed
analysis and list of ingredients take into account the water in the product. Essentially,
what this is saying, once again, is that the guaranteed analysis and list of ingredients
can be misleading when comparing two products because of moisture.
To illustrate this concept consider the labels on two foods, food A and food B. Food A
has 15% water. Thus 85% of the contents are dry ingredients. Food B has 70% water.
Thus 30% of the contents are dry ingredients. If you assume that the minimum protein
level listed on each label is the actual protein level, and food A has a minimum protein
level of 20% and food B has a minimum protein level of 15%, it would appear that food A
has more protein. However, to accurately determine which food had the higher protein
level you would have to consider each food on a dry matter basis since the amount of water
in each food is very different.
To determine the amount of protein on a dry matter basis, you simply divide the % protein
by the % dry ingredients and multiply by 100. This will give you the % protein on a dry
matter basis. So, for food A, 20/85 x 100 = 23.5%. And for food B, 15/30 x 100 = 50%.
Thus, food A is actually 23.5% protein and food B is actually 50% protein. So, food B
has more protein than food A despite the fact that the label appeared to show the opposite.
Also, 50% protein is way too much protein for a dog and is at the extreme high end of
necessary protein for a cat. If levels this high are fed, serious problems may result.
As one can see, there are several ways that pet food labels can be misleading. All of
this may make one wonder how they would ever know what food to choose. Next we will
discuss some of the basic nutrients found in pet food in order to help you, the consumer,
choose a food that is appropriate for your pet.
Protein. Most people know that protein is a very important nutrient. Proteins
play a critical role in virtually all parts of the body. If an animal has too little
protein serious problems can result. However, people often falsely assume that more
protein must certainly be better. If an animal is fed a high level of protein for a
long period of time, serious kidney disease may result. Thus feeding an appropriate
level of protein is quite important. Generally, cats need more protein than dogs, young,
growing animals need more protein than older animals, and pregnant or nursing animals
need more protein than animals that are not reproductively active. Hills Veterinary
Nutritionists (HVN) recommend 15-28% protein for adult dogs, 28-35% protein for puppies
and pregnant/nursing dogs, and 15-20% protein for old dog. For cats, 30-45% is recommended
for adults and 35-50% is recommended for kittens and pregnant/nursing cats. These
percentages are all on a dry matter basis. As previously discussed, taking % protein
on the label, dividing by % dry material in the food and multiplying by 100 will give
the % protein on a dry matter basis. The same calculation can be used to convert all
nutrients to a dry matter basis.
Fat. Fats are a concentrated source of energy. They provide over twice the
amount of energy as fats or carbohydrates. While fats generally receive a negative image,
it is important to remember that they are necessary for the metabolism of certain vitamins,
for insulation of the body and some organs, as well as for storage of energy. It is
equally unhealthy for an animal to have no fat as it is for an animal to be obese. HVN
recommend 5-20% fat for adult dogs and 10-30% fat for adult cats. Up to 30% fat is
recommended for puppies or pregnant/nursing dogs and up to 35% fat is recommended for
kittens or pregnant/nursing cats. For obese animals, fat should be between 5-15% for
dogs and 8-12% for cats. Once again, all of these percentages are on a dry matter basis.
Calcium and Phosphorus. Calcium is necessary for proper bone growth and remodeling
as well as for proper muscle function. Phosphorus is also necessary for proper bone
formation. Calcium needs to be present not only at a particular level but also at an
appropriate amount with respect to phosphorus. The calcium to phosphorus ratio should be
between 1.1 : 1.4 -1. If the phosphorus level is too high, calcium levels in the body can
become too low. If this occurs, the body will start to remove calcium from the bones.
The result can be lameness, spontaneous bone fractures, and kidney problems. If too much
calcium is fed, especially to large breed dogs when they are young, bone growth can
actually be decreased and problems such as OCD and hip dysplasia can result. HVN
recommend calcium at .5-.9% for adult dogs and double that for puppies and pregnant/nursing
dogs. Similar levels are recommended for cats. Phosphorus is recommended at .2-.8% for
adult dogs, .8-1.4% for puppies and pregnant/nursing dogs, .3-.8% for adult cats, and
.8-1.4% for kittens and pregnant/nursing cats. All percentages are on a dry matter basis.
Magnesium. Magnesium is necessary for many of the chemical reactions that occur
in the cells of the body. Excessive magnesium, especially in cats, can lead to the
formation of crystals and stones in the bladder. The Hills Veterinary Nutritionists
recommend .04-.15% magnesium for adults and old age dogs and .04-.1% magnesium for
adult cats. Levels vary only slightly for young and pregnant/nursing animals. The
percentages listed are on a dry matter basis.
Sodium. Sodium is primarily added to pet foods to enhance flavor. It is a well
known fact that excessive sodium can be a factor in heart and kidney problems. The
recommended sodium level is .1-.4% for adult dogs and .2-.6% for cats on a dry matter
basis. Levels vary only slightly for young and pregnant/nursing animals.
Protein, fat, calcium, phosphorus, magnesium, and sodium levels should all be taken into
consideration when choosing a pet food. Before comparing labels be sure to convert the
values on the label to a dry matter basis since the amount of water in different products
can make a significant difference. Also, be sure to compare the levels of the specific
nutrient to a list of acceptable nutritional ranges, such as the levels listed above by
the Hills Veterinary Nutritionists. This will give you a fair idea of how foods compare
to each other. However, remember that it is possible for a food to have nutrients present
in a proper amount, but it is not a guarantee that they can be effectively digested and
utilized by the animal. There is virtually no way to determine this from reading the
label. If information on the label is missing or inadequate, do not hesitate to contact
the manufacturer for additional information. If they are not willing to provide you
with the information you request, then perhaps you should be hesitant to feed their
food to your pet.
Our online webstore has a variety of foods available for purchase and shipped to your door!
See link below.
The information provided is for educational purposes only and is not
intended to take the place of your regular veterinarian. Please do not hesitate
to contact your regular veterinarian if you have questions regarding your pet.
Karen Blakeley, DVM, MPH
13 December 2002