Evaluating a pet food ingredient/composition list
Is the ingredient list, (or the composition list as it is now known), the first thing you look at on a pet food label?  If it is, then you are not alone.  Over half of pet owners surveyed say that the ingredients are the most important factor in choosing a pet food. 

Although this is a great first step, do remember that the composition list does have limitations as it tells very little about the nutritional value of the ingredients in the food. 

Pets require nutrients, not ingredients: a diet full of great-sounding ingredients can be less nutritious than a diet containing ingredients that, at least to us as dog owners, could sound less appealing.  A pet food made of chicken breast, peas and white potato may sound like something we would eat, but that doesn’t make it healthier or higher quality than a diet containing pork liver, corn flour and fish meal.  There can also be a big difference in quality and nutrition between two diets that have very similar ingredients i.e. – not all chicken is of the same quality.

With today’s ever-expanding pet food market, some manufacturers use composition lists to increase the appeal of the diet to us, the pet owners.  These diets may be full of attractive sounding ingredients – blueberries, cranberries, smoked salmon, celery, parsley and kelp – they sound healthy, but may have unproven benefits for pets or may be present in miniscule amounts and provide little to the diet but do promise added expense.  Having more ingredients means the need for more quality control (and more time and expense) to ensure that the finished product adheres to the desired nutrient formulation and avoids unsafe levels of contaminates (e.g, some kelp sources have high levels of arsenic).  Unfortunately, this degree of quality control is not always practiced. 

COMPOSITION LIST ORGANISATION
Although the composition list  cannot be used to determine the quality of the food, it can be used to roughly judge the relative amounts of an ingredient in a food when compared to other ingredients.  Ingredients must be listed in descending order of weight (including water weight).  Therefore, ingredients that appear at the top of a composition list – typically the main proteins, carbohydrates and fat sources – are present in higher amounts by weight in the food than the items at the bottom, such as vitamin and mineral supplements.

Because water is included in the weight of the ingredients, ingredients with a high water content (like meats and vegetables) are going to be listed higher than similar amounts of dry ingredients even though they may contribute fewer nutrients to the overall diet.  They may simply weigh more because of the heavier water weight.  So just because chicken or lamb is the first ingredient doesn’t mean that pet food has more meat than one which has dried chicken or dried lamb a little farther down the composition list.  In effect looking for ‘dried chicken’ as a first ingredient instead of ‘chicken’ is often recommended as it contains very little water.  Likewise canned diets will nearly always include water or broth as their first ingredient as tey are 70-80% water by definition. 

Chicken vs Dried Chicken
Chicken is approximately 70% moisture, while chicken meal contains less than 10% moisture, so chicken will be much higher on a composition list than chicken meal, even if both ingredients are providing the same amount of actual chicken!

In addition to guidelines on the order of ingredients in the composition list, regulatory definitions must be adhered to by manufacturers for almost all pet food ingredients.  These definitions describe what that ingredient can and cannot include and also what it is named.

As an example the definition of meat by product allows the inclusion of organs and bones BUT NOT intestinal contents, hooves, teeth, hair and horns.  Despite being clearly defined by AAFCO and FEDIAF, a quick internet search will find multiple websites falsely stating that meat by-product contains hooves, horns and faeces – all things which are expressly forbidden in the definition.  This practice is very deceptive as it may influence consumers to think that certain ingredients are “bad” after reading incorrect information. 

For more information on effective ways to seek out nutrition information on the internet see “The Savvy Dog Owner’s Guide to Nutrition on the Internet” and “The Savvy Cat Owner’s Guide to Nutrition on the Internet” (both available at http://www.wsava.org/nutrition-toolkit).

CURRENT TRENDS
‘Healthful’ – A number of current pet food trends can be seen in the ingredient lists of today’s pet foods.  One previously mentioned trend is to include ‘healthful-sounding’ ingredients such as fruits and vegetables in pet foods, but they are present in such small amounts that they are unlikely to provide much nutritional value at all. 

Top Tip – A good rule of thumb is that any whole food ingredient (such as blueberries, eggs, artichokes or tomatoes) that is listed below a vitamin or mineral supplement in the composition list is unlikely to be present in nutritionally significant amounts. 

The Exotic – Another recent trend is to include more more exotic and previously uncommon ingredients in pet foods, such as bison, venison, rabbit and quinoa.  These ingredients were rarely used in pet foods in the UK in the past and thus represented novel (new) ingredients.  Novel ingredients can be used to help diagnose food allergies, so the fewer novel ingredients, the more challenging this diagnosis becomes.  In other words although these exotic sounding ingredients sound very appealing they are often not the friend of the vet who is wanting to limit the types of proteins that a dog may be exposed to.

In summary, the composition list on pet foods is a good place to start but it has limitations as it cannot assess the quality or nutritional adequacy of a pet food.  Understanding how the composition list is organised and used by the manufacturers can help you, the pet owner and vets make better, more informed decisions about pet foods.