Optimal Diets for Pets

In the previous Blog, we discussed the ongoing debate about raw versus cooked food diets for pets.

Here we are going to address some lingering questions.

Should it include raw meat or cooked meat?

Many of us in the veterinary community, including myself, have seen first-hand the health and vigor of dogs and cats fed raw diets. These animals just ‘shine’ in all respects; the experiential findings based on years of observations by dedicated holistic veterinarians and animal nutritionists support this conclusion. To criticize all raw diets on the basis that they are inherently harmful is misleading, and conveys an inflexible message.

In the USA, the FDA’s Center for Veterinary Medicine controls the pet food industry, and this organization mandates a zero-tolerance policy of Salmonella for all pet foods, not just the ‘cooked’ products. Further, the top raw food manufacturers also test each batch of food before releasing it into the marketplace.

As anyone who follows pet food recalls knows, commercially produced kibbled products and treats are recalled on a regular basis due to contamination with Salmonella spp., E. coli and Campylobacter spp.

Should the meat be grass-fed rather than grain-fed?

Grass-fed meats are preferred over those meats derived from grain-fed animals, because grain residues reside in the flesh of the carcass. The most commonly fed grain is corn, which often is of genetically modified origin (GMO) and field grade. Rice, soy and sorghum are also commonly fed.  Additionally, some pets are intolerant of these grains.

What about fish?

Both white-colored fish and salmon and their oils are common ingredients in pet foods and provide an important source of the omega-3 fatty acids needed to sustain the skin and coat, brain and other body metabolic functions. The fish should be farm raised or at least be assured to be free of mercury.

What about the need for some vegetables and fruit in a complete diet?

Unlike cats that remain primarily as obligate carnivores and need some meat, dogs have evolved from their ancestral wolves to be obligate omnivores. They have adapted to domestication by developing three additional genes that allow them to digest and assimilate starch. Regardless, an all-meat diet is not balanced for long term use, especially in dogs, and so some vegetables and fruit (making up 30-70% of the total diet) should be included for roughage, fiber and pro-biotics. Some also add organic tripe.

Dogs (and even cats) can be healthy when maintained on strictly vegetarian diets, although these diets must be nutritionally complete and balanced. Pet caregivers should regularly monitor urinary acidity and should add products such as cranberry extracts, if urine becomes too alkaline (i.e. pH > 7.0).

Suggested vegetables and fruits include: Carrots and green beans, as functional carbohydrates, are a source of soluble fiber, and have anti-inflammatory and antioxidant effects. Simply chop them up into small raw pieces, or lightly steam them as this helps with digestibility. We also like spinach or kale, and zucchini.

Apples, pears and bananas protect the heart and help control diarrhea. Apples also improve brain health, lung capacity and cushion joints; whereas bananas help strengthen bones and control blood pressure. Pears provide a rich source of fiber. Also use fresh or frozen blueberries and cranberries, plus watermelon.

What about taurine levels in certain types of dog foods and the possible connection between grain-free diets and dilated cardiomyopathy (DCM), which is also known as canine heart disease (CHD).

The US Food and Drug Administration (FDA) released a statement on July 12, 2018 that it is investigating a possible connection between grain-free diets and DCM, which is also known as CHD.

But, many factors need to be considered in addressing this situation:

• Genetic predisposition
• Diet
• Scientific research thus far
• Taurine requirements for dogs
• Interaction between foods when passing through the body
• Interaction between foods and the body itself

What we do know:

• Taurine is an amino acid. Amino acids are found in animal-based protein sources and plant sources like soy at varying amounts, depending on the type of meat or plant.
• Taurine deficiency can lead to CHD in humans, cats and dogs.
• All breeds and sizes of dogs can develop CHD. However, CHD is more common in larger and giant breeds such as Great Danes, Boxers, Newfoundlands, Irish Wolfhounds, Saint Bernards and Doberman Pinschers. American and English Cocker Spaniels also have a higher incidence.
• At this time, taurine is notconsidered an essential, food-sourced amino acid for dogs. It is synthesized in the liver from the amino acids cysteine and methionine.
• Although taurine is present in today’s dog food, the label does not need to reflect its presence or meet any minimum requirement.
• Cats, however, dohave a need for food-sourced taurine to prevent CHD; and there is a minimum required amount for cat food.
• Cooking temperature is stated to adversely affect or significantly degrade amino acid levels in foods.
• A published study found, “The amount of taurine that remained in a feed ingredient after cooking depended upon the method of food preparation. When an ingredient was constantly surrounded by water during the cooking process, such as in boiling or basting, more taurine was lost. Food preparation methods that minimized water loss, such as baking or frying, had higher rates of taurine retention.”
• Cysteine is one the essential amino acids that dogs need to form taurine. Another published study by Weiss et al concluded, “Eight (including cysteine) of the 20 standard amino acids decompose at well-defined, characteristic temperatures, in contrast to commonly accepted knowledge. Products of decomposition are simple. The novel quantitative results emphasize the impact of water and cyclic condensates with peptide bonds and put constraints on hypotheses of the origin, state and stability of amino acids in the range between 200 °C and 300 °C.” Put simply, high temperatures do cause the breakdown or change these amino acids, including cysteine.
• High levels of legumes or potatoes appear to be more common in diets labeled as “grain-free,” but it is not yet known how or if these ingredients are linked to cases of DCM.
• The FDA is simply stating a trend, which no doubt will lead to much needed research.
• The FDA is notdismissing the prior research as invalid. As the FDA puts it, “The underlying cause of DCM is not truly known, but is thought to have a genetic component.”
• The FDA is also notsaying that pet caregivers should stop feeding grain-free foods.

Selected Reading

Axelsson, E, Ratnakumar, A, Arendt, MJ, et al. The genomic signature of dog domestication reveals adaptation to a starch-rich diet. Nature 2013; 495: 360–364.

Dodds, WJ, Laverdure, DR. Canine Nutrigenomics: The New Science of Feeding Your Dog for Optimum Health. 2015. DogWise Publishing, Wenatchee, WA, .323 pages.

Ko, KS, Fascetti, A. Dietary beet pulp decreases taurine status in dogs fed low protein diet. J An Sci Technol 2016: 58: August.  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4971673/.

Weiss, I, Muth, C, Drumm, R,  Kirchner, HOK. Thermal decomposition of the amino acids glycine, cysteine, aspartic acid, asparagine, glutamic acid, glutamine, arginine and histidine. BMC Biophysics, 2018;11(2).

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5807855/.