Potatoes have a high glycaemic index (GI). The glycemic index describes carbohydrates relative to their effect on our blood glucose levels. Choosing low GI carbs - the ones that produce only small fluctuations in our blood glucose and insulin levels - has been linked to long-term health by reducing your risk of heart disease, diabetes, and sustainable weight loss. Horizon uses peas which have a considerably lower GI than potatoes or tapioca (which are common in other grain-free pet foods).

Additionally, cooking potatoes results in the formation of acrylamides. There is evidence that exposure to large doses of acrylamides can cause damage to the male reproductive glands. Direct exposure to pure acrylamide by inhalation, skin absorption, or eye contact irritates the exposed mucous membranes, e.g. the nose, and can also cause sweating, urinary incontinence, nausea, myalgia, speech disorders, numbness, paresthesia, and weakened legs and hands. In addition, the acrylamide monomer is a potent neurotoxin.

Acrylamide cannot be created by boiling, and nearly all uncooked foods do not contain any detectable amounts. Browning during baking, frying or deep-frying will produce acrylamide and over-cooking of foods will produce large amounts of acrylamide. Acrylamides can also be created during microwaving. Because of the high heat and pressure, and the speed at which ingredients are cooked during extrusion, it is hypothesized that extrusion of potatoes would cause the formation of acrylamides.

Cancer

Acrylamides are considered a 'probable carcinogen', and even though acrylamides are produced at very low levels and your dog would have to eat a considerable amount of food to consume enough acrylamides to statistically raise its risk of developing cancer, the fact that cancer is a growing concern in pets is sufficient reason for us to not include it.

According to a 2005 review, acrylamide reliably produces various types of cancer in experimental mice and rats. However, studies in human populations have failed to produce consistent results, and it remains unclear whether this is due to a reduced risk in a natural setting or the methodological difficulties inherent in such studies. For example, it might be difficult to isolate the effects of acrylamide because it is so ubiquitous in western diets.  Because of this, Horizon does not use potatoes in any formulations.