[pullquote]Ideally, dogs will consume animal protein because the essential acids present are closest to those that dogs need.[/pullquote]In addition to quantity, the quality of protein in a dog’s diet is very important. Quality refers to the balance of constituent amino acids present in a protein source. Proteins have a total of twenty amino acids, about half of which dogs make on their own. Amino acids that aren’t made are considered “essential” because they must be eaten. The quality of protein is determined by how well the proportions of essential amino acids present in a protein match the needs of the animal that is eating it. Ideally, dogs will consume animal protein because the essential acids present are closest to those that dogs need. Grains also contain essential amino acids, but in much lower quantities. Because meat is so much more expensive, pet food manufacturers will often use grains as the source of protein and add in the necessary amino acids.
We all need fat and mixtures of fatty acids for many reasons including to help our bodies absorb vitamins, for cell function and for energy. For dogs fat should be about 11-12% of their diet. Saturated fats don’t matter as much for dogs as they do for humans because dogs have a lot more HDL (good cholesterol). What does matter are the amounts of Omega-3 and Omeaga-6 fatty acids and the balance between them. From Omega-6 dogs require linoleic acid to prevent skin and coat problems, and from Omega-3 they require alpha-linolenic acide (ALA) which their bodies convert to Docosahexaenoic acid (DHA) which is vital. The balance or ratio between the fatty acids is important because too much Omega-6 may inhibit the conversion of ALA to DHA, but we don’t know enough about it yet. Meat, eggs, fish and nuts are all good sources of fat for dogs.
Vitamins and Minerals
Among the most important minerals are calcium and phosphorus needed for milk production, growth and bone formation. The AAFCO profiles recommend 1% calcium and .8% phosphorus in dry ingredients. In the wild, dogs get this from bones and organs of prey, and pet food manufacturers normally use by-products, bone meal and calcium phosphates or carbonates. For home-prepared dog food, fruits, vegetables, meat and bones are excellent sources of vitamins and minerals, or supplements can be added as they are to commercial pet foods. The list of essential vitamins is extensive, and includes vitamins A, D, E and B12.
What about the abundance of the supplements, foods with special nutrient claims and treats? In Part II I mentioned that anything marketed as having something above and beyond the norm – the AAFCO profile standard – is probably a gimmick, but let’s dig a little deeper and look at some of the most popular supplements to understand why:
- Taurine: dogs don’t actually need it, they make their own.
- Chondroprotectives(like chondroitin sulfate and glucosamine): the studies that have been down show only a mild placebo effect on the human owners (meaning we tend to believe that the pill is helping the dog), but there is no evidence for actual improvement in joints.
- Probiotics: if you want to give your dog the good bacteria, stick with fresh yogurt. Processing or freezing yogurt kills almost all of the useful probiotics. If your dog enjoys the $8 frozen treats, by all means buy them. But realize that it’s more of a junk food treat and not a nutritional supplement.
- Vitamin C: it’s often added to replace what is lost through processing, but dogs make their own.
- Omega 3 fats: there is enough in the normal food, without extra.
- Treats: they contain a lot sugar. Candy for your dog, money-makers for the companies.
- Antioxidants: it has been shown that in humans, over-consumption might have risks. Why risk the health of our dogs?
2. Risks of Commercial Pet Food
Most of the time commercial pet food is fine. Nobody has proven that it is any better or worse than the alternatives. So if commercial pet foods are pretty much all the same and probably nutritionally adequate, what are the risks or disadvantages?
- Sometimes the recipe goes wrong: Feeding Studies
Part II of this series outlined the various ways that commercial pet food companies can provide the required statement of guaranteed analysis: by conducting a feeding study, by formulating foods specifically to meet the AAFCO profiles, or by making foods with formulas similar to those already tested in a feeding study. The best way to guarantee that a food recipe is nutritionally adequate is, not surprisingly, to conduct a feeding study. But feeding studies are expensive and time consuming, so most companies opt for one of the other choices, and this is where problems can arise.
Merely formulating a dog food recipe based on the AAFCO nutrient profiles is insufficient because, without a feeding study, it is impossible to tell how well dogs are actually digesting and using the combination of nutrients that they consume. The AAFCO has tried to compensate for this by making the nutrient profile requirements higher than those deemed necessary by the NRC, but in the end, if your pup isn’t digesting the nutrient, it doesn’t really matter if he is pooping out 10 milligrams or 100 milligrams of a vitamin. He is still pooping it out.
- Sometimes the ingredients go wrong: Recalls
Pet food recalls are a big deal. Not just because tainted food is so dangerous, but because having a highly concentrated and incestuous industry means that one bad ingredient from one source can contaminate an enormous percentage of the products in the marketplace.
The 2007 recalls of melamine-tainted foods are perhaps the most tragic example of what happens in such an industry when feeding studies aren’t required. Menu Foods, a company that produced dog food for several well-known names, was importing what it thought was wheat gluten from China, but was in fact wheat flower tainted with Melamine. Melamine, when added to wheat flour, looks like wheat protein and contains 67% nitrogen, but is much cheaper than producing actual wheat protein, and, it turns out, toxic for cats and dogs. The tainted ingredient worked its way into many, many brands of foods, and without adequate feeding studies the problem was not discovered until many, many pets had died.
Tainted food is not uncommon, and the industry is not well regulated. Something to keep in mind.
- Sometimes we just don’t know: the Veterinarian Education Deficit
Feeding your loved ones an unrecognizable mixture of processed stuff instead of real, fresh food might have risks that we just aren’t aware of yet. Without long-term studies (which there aren’t), how do we know if the stuff in the bag is up to par? You might think that getting a recommendation from your veterinarian is the best way to go, and while some vets may have the answers, most don’t. Veterinarians have relationships with pet food companies that are similar to the relationships between doctors and pharmaceutical companies – they earn money by promoting specific brands of food. But the situation with vets should be of concern to pet owners for another reason: most of them get very little formal education with respect to small animal nutrition. Much of what veterinarians know is from the pet food manufacturers who devote an enormous amount of money to training and marketing themselves.
3. Alternatives and the Risks