Canned Food & Calculating Carbs

The single best way to be sure you are feeding acceptable food is to learn to read labels.  Stay away from foods with grains (including rice and soy), vegetables, fruits, gravy, corn starch or corn syrup, and wheat or corn glutens whenever possible.  Dr Hodgkins book, Your Cat, contains a wealth of information on species appropriate diet, and debunks the myths about "life stage" pet food. We consider it THE owner’s manual for cats and strongly recommend you purchase a copy.

Many owners have been feeding Purina DM prescribed by their vets when they find DCC.  Purina DM is lower in carbs than some cat foods, was invented by Dr. H (she still holds the patent), and currently calculates at around 5% carbs for both the US and the UK versions.  The ingredients are not the greatest, however, but the food can be used if necessary.

It is important to learn to calculate the carbohydrate content of canned food - it's an easy formula to remember once you've done it a few times, and will be invaluable to you when considering the purchase of new foods.

How to Calculate Carbs on a Dry Matter Basis
 
First, use the Nutritional Analysis figures whenever possible, as these are true numbers for each flavor, while the Guaranteed Analysis numbers are averages.  Unfortunately, manufacturers seldom print NA numbers on the food labels, using instead the GA numbers.  Their websites will sometimes provide NA info. 

Looking at the Guaranteed Analysis (GA) on the label, add up the values for protein, moisture, fat, fiber, and ash (if listed - sometimes it is not).  Then subtract those values from 100 - the difference is the wet matter carbs.  So, if we have a food with 78% moisture, 11% protein, 5% fat, 2% fiber and 1.5% Ash,  the calculation would look like this:

78.00 + 11.00 + 5.00 + 2.00 + 1.50 = 97.50  Subtract that from 100, and the remainder, 2.50,  is the WET matter carbs.

However, when comparing the carbohydrate contents of any food, it must be done on a dry matter basis, even with dry food, as dry does contain some small amount of moisture.  So, looking at the Guaranteed Analysis on the label once again, subtract the moisture content from 100 - in this case, the difference is 22.  Then divide your wet matter carbs by this number.  So...

2.50 divided by 22. = 11% carbs on a dry matter basis.
 
This is an easy formula, and once you've done it a few times, you will be able to look at the GA and pretty much know what the carb content is based on the values given.   Remember, though, ingredients are just as important as the carb content - you want food with no grains (including rice or soy) no veggies, fruits, glutens, or cornstarch, and no gravy.  Broth is fine, as long as it is not thickened with starches.

Many low carb canned foods contain fish, beef or meat of unknown origin but are great for transitioning cats from dry to canned.  However, they may be inappropriate for diabetic cats, or cats with food allergies or gastrointestinal disorders. Fish should be fed sparingly, but can serve as an excellent tool for transitioning cats on to canned food. Likewise, liver varieties can be addictive and contain Vitamin A which can be toxic to cats in excess, therefore should not be fed in large amounts.

Pet food companies are continuously changing their recipes for pet food. As a result, even though the food lists in the Info stickies for various countries contain foods that were low in carbs at the time of compiling the lists, we strongly urge you continue to verify the carb content from time to time.

If you need to syringe or tube feed your cat, there are several formulas that can be used easily in a feeding syringe. The first is Stage 1, all meat and broth baby food, with no onions, veggies or cornstarch, mixed with a spoonful of plain, unsweetened, full fat yogurt and a little warm water. Gerber and Beechnut are two popular brands available in the US - please be sure to check the ingredients.  A minimum of 9 or 10 ounces should be given over a 24 hour period.  If this is fed for anything more than a few days, taurine should be added to it.

Another formula that needs no supplementation and is often better received by the cat is pureed Fancy Feast in the cat's favorite flavor; mixed with a spoonful of full fat yogurt and some warm water or no salt chicken broth.  Usually, 6oz daily will suffice, but larger cats or severely malnourished cats may need more.

Prescription foods such as Hills A/D have inferior ingredients, and should not be used.

Updated May 2011