Dogs will eat just about anything. Despite a popular misconception, dogs cannot instinctively tell what foods are healthy for them and what foods can make them sick. Pet food companies are required to list food ingredients on a side label, but some ingredients can be difficult to interpret. According to the Whole Dog Journal, which does not accept advertising, the worst pet foods will contain these unclear ingredients.

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Meat Byproducts

  • Dog food may meat byproducts or poultry byproducts. These are much cheaper than meat. Byproducts are considered any part of livestock except for meat. It can include any tissue, tendons, skin, internal organs, heads, feet, beaks and rectum. Although meat byproducts may give the food flavor, they may not be the safest or most nutritious sources of nutrients for a dog. By using byproducts in pet food, the best cuts of meat can go to feed people.

Animal Digest

  • What animal digest is remains a point of debate. The Whole Dog Journal defines animal digest as the food resting in the digestive tract of livestock at the time they were slaughtered. The Association of Canadian Feed Control Officials (CFCO) defines it as “material which results from chemical and/or enzymatic hydrolysis of clean or undecomposed animal tissue.” It’s not clear at what point animal digest differs from manure. Manure may contain salmonella. However, many livestock animals are not given food for a couple of days before slaughter to clear out the digestive tract and reduce the risk for salmonella.


  • Meal may be listed in pet food ingredients as meat meal, bone meal, meat and bone meal or animal byproduct meal. Meal is used as an inexpensive way to keep the protein content of dog food to a certain level without using expensive cuts of meat. Meal is a finely ground porridge like substance that can be made from the entire animal used for dog food. It can be made into various thicknesses and used for wet food or baked for dry food. It does not have to include meat. It can include hide, hair, hooves, horns, feet, internal organs and the undeveloped eggs of poultry. CFCO mentions that no feathers, stomach contents or manure should be in the meal, but adds that meal is not entirely free of them because it is impossible to entirely remove all of those materials in modern slaughterhouses.