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Mixing Raw & Kibble

By: Marta Young

Can I feed a little raw, or raw sometimes?

The short answer is “No”. We don't recommend mixing raw with kibble (dry food) or canned, commercial or home cooked diets. We strongly believe that it is misguided to say “some is better than none” or that you can feed a raw meal or snack occasionally alongside your pets' regular food.

Why is this? Well, to start off let's look at Gastrin. Gastrin is a hormone that stimulates secretion of gastric acids and is secreted into the bloodstream in response to the presence of food in the stomach. It controls the muscles of the stomach, reducing motility and slowing gastric emptying. This allows the stomach to hold and process a large meal.

Gastric pH of our companion animals are the same when not eating, whether fed commercial, home cooked or raw food. However, when a meal is introduced, what is in that meal triggers different acidity levels in those same animals. The amino acids in meat and raw bones triggers a greater gastrin release than the carbohydrate-rich meals from commercial foods or home-prepared meals that include starchy or green vegetables. These starches and plant material reduce the amount of hydrochloric acid stimulated by the gastrin response. So, rather than the naturally low pH (high acidity) of 1-2 you would see if the same pet was given a meal of raw meat and bones, they only achieve the relatively high pH (low acidity) of around 4.

Why is this important? Our pets need this higher level of acidity to break down the food (especially bones), and the longer digestion time produced by the higher gastrin response. If the stomach acid levels and digestion times are reduced by the introduction of carbohydrates, you risk incomplete digestion of bone, and the inability to fully process and absorb the nutrients from the meat and organ. If raw meat and bones are mixed with or fed alongside the high carbohydrate-content commercial foods, you might see the dog struggling to digest the raw meat and bone properly. This can result in bone sitting in the stomach for long periods of time; vomiting of bone, passing undigested bone in the feces, or bowel impaction due to improper digestion.

This lower-acid environment and shorter digestion time also opens your pet up to the risk of pathogens which would ordinarily be destroyed with the lower pH digestion triggered by raw meals.

According to a study by Saint-Hilaire in July 1960 gastric pouches from dogs were isolated and used to understand the function of a dog’s stomach. Their conclusion “The foods with the highest secretory equivalent values belonged in the meat, fish, and dairy products categories. The foods with the least ability to stimulate acidity had the most carbohydrate content: fruit, bread, cereals, green peas, oatmeal and potatoes. Most of these foods are common ingredients in processed pet foods.” It was concluded protein was the most important acid-stimulating factor.

Feeding kibble and processed foods made up mainly of ingredients not suitable to our carnivorous companions may reduce their immune system as well. This is the equivalent of eating a highly processed 'fast food' diet for humans. The wrong ingredients, and highly processed to boot, is not going to give your pet the best nutrition for health and wellbeing, potentially making them more susceptible to illness and disease. It takes more effort for your pets' bodies to process and try to digest these ingredients that they are not designed to ingest on a regular basis. This may slow the elimination of waste, cause digestive upset, and even lead to vomiting and diarrhea. Pets on commercial diets that are exposed to pathogens like salmonella or listeria get very ill (thus all the recalls every year for contaminated pet food). A raw fed pet may very well weather exposure to these pathogens, neutralizing and destroying them in their lower pH digestive system and eliminating them without ever being visibly affected by it.

References:

  • Raw Essentials Gastric Acidity & Mixed Feeding by Dr. Lyn Thomson

  • Lichtenberger, L.M. (1982). Importance of food in the regulation of gastrin release and formation. American Journal of Physiology 243, G429-441.

  • Saint-Hilaire, S.,Lavers, M.K., Kennedy, J. & Code, C.F. (1960). Gastric acid secretory value of different foods. Gastroenterology, 39(1).

  • DelValle, J. & Yamada, T. (1990). Amino acids and amines stimulate gastrin release from canine antral G-cells via different pathways. Journal of Clinical Investigation, 85, 139-143

  • Smith, J.L. (2003). The role of gastric acid in preventing food borne disease and how bacteria oversome acid conditions. Journal of Food Protection, 66(7):1292-1303

  • Martinsen, T.C., Bergh, K. & Waldum, H.L.(2005). Gastric juice: a barrier against infectious diseases. Basic and Clinical Pharmacology and Toxicology, 96(2):94-102

  • Hewson-Hughes, A.K., Hewson-Hughes, V.L., Colyer, A. Miller, A.T. McGrane, S.J. Hall, S.R. Butterwick, R.F. Simpson, S.J. & Raubenheimer, D.(2012, 23 October). Geometric analysis of macronutrient selection in breeds of the domestic dog, Canis lupus familiaris. Behavioral Ecology, doi:10.1093/beheco/ars168

  • Beasley DE, Koltz AM, Lambert JE, Fierer N, Dunn RR. (2015) The Evolution of Stomach Acidity and Its Relevance to the Human Microbiome. PLoS ONE 10(7): e0134116. doi:10.1371/journal.pone.0134116

  • Lennard-Jones, J.E., Fletcher, J. & Shaw, D.G. (1968). Effect of different foods on the acidity of the gastric contents in patients with duodenal ulcer. Gut (BMJ), 9, 177-182.

  • Brooks, F.P. (1985). Effect of diet on gastric secretion. American Journal of Clinical Nutrition, 42, 1006-1019.

  • Hunt, R.H. (1988). The protective role of gastric acid. Scandinavian Journal of Gastroenterology, 23(supp146):34-39

  • Cook, G.C.(1985). Infective gastroenteritis and its relationship to reduced gastric acidity. Scandinavian Journal of Gastroenterology, 111:17-23

  • Simpson, S.J., & Raubenheimer, D. (2012). The Nature of Nutrition: A Unifying Framework from Animal Adaptation to Human Obesity. Princeton University Press.

  • Callaway, E. (2014). Microbes help vultures eat rotting meat. Nature, 26 November 2014.

  • Thomson, L., & Mair, A. (2013). Analysis of the 2012 American Veterinary Medical Association Position statement on Raw Feeding

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