Unconventional pet foods (Proceedings)
The history of commercial petfoods is relatively short.
The history of commercial petfoods is relatively short. While some food products intended for dogs or cats have been available for over a century, it wasn't until the 1950's when the concept of "complete and balanced" petfoods became established. For the most part, petfoods have been divided into three conventional forms: dry, canned, and soft-moist (alternatively, "semi-moist"). Traditionally, they have been comprised of animal and vegetable proteins, grains, and added vitamins and minerals.
Within each category of petfood there may be variations. For example, most dry food is extruded, but some is baked. The extruded product expands with air as it leaves the extruder, whereas the baked is denser. Both are typically around 10% moisture after processing. Soft-moist foods are often extruded as well, but at a higher moisture content (~33%) and without the introduction of air. These can take many shapes, from those that resemble ground beef or meat chunks, to the hanging "sausages" often seen in pet store displays. On a dry matter basis, they are roughly equivalent to dry foods in nutritive value. Their high moisture content is retained by use of simple sugars (in lieu of the starches incorporated in dry foods) and humectants such as propylene glycol, or more commonly today, glycerol and organic acids. "Canned" foods (~78% moisture) may be in traditional cans but also a wide variety of foil-covered plastic trays, pouches, and other containers. However, all must meet the Low Acid Canned Food regulations to ensure proper processing and safety.
Recent years have seen an influx of new ingredients, new forms, and even new categories of petfoods. All strive to define their niche in the market place, but must follow the same regulatory requirements as dictated by the Food & Drug Administration (FDA) and the states that enforce their regulations patterned after the Association of American Feed Control Officials (AAFCO) model regulations. The veterinarian must be aware of these products and their relative attributes to make sound recommendations to clients.
Many, if not the majority of petfood manufacturers, now sell a "natural" line of products. Under AAFCO definitions, a "natural" product excludes all ingredients that are chemically synthetic. However, it is highly infeasible to formulate a complete and balanced product without reliance on some synthetic trace nutrients like vitamins, minerals, and taurine. Thus, while some treat products may indeed be "natural," use of the term in most cases require further qualification. To that end, AAFCO allows use of a disclaimer, e.g., "natural with added vitamins and minerals" to qualify the addition of synthetic nutrients. Thus, the bulk of ingredients in a "natural" petfood and a traditional petfood may be the same. One difference is that the former may not contain chemically synthetic non-nutritive ingredients, such as preservatives, flavors, or colors, except in amounts that may be unavoidable through good manufacturing practices. Therefore, "natural" preservatives, such as mixed tocopherols (extracted) or citric acid (fermented) vs. chemically synthetic ethoxyquin or propyl gallate are often used in formulations. There is little scientific basis to show that "natural" products are safer, healthier or more nutritious. In fact, some have questioned the ability for natural preservatives to prevent product degradation as effectively as the synthetic, which if true, could lead to spoilage, loss of nutritive value and potential adverse effects (Cowell et al., 2000). Regardless, to the extent these few ingredients are important to the pet owner's purchasing decision, these products are very similar to conventionally-produced products.
"Organic" is not the same as "natural." Rather, it describes a whole system of production and manufacturing of ingredients and products. While there are some exceptions, organic grains must be grown without genetic engineering or use of synthetic pesticides, herbicides, or fertilizers. Similarly, organic beef must be from cattle fed organic feeds, not treated with antibiotics, steroids or other drugs, and allowed daily access to outside areas. Depending on the percentage of organic ingredients, foods may be labeled as "100% organic," "organic," or "made with organic ____." These and other requirements were promulgated via the US Department of Agriculture's National Organic Program (NOP). Third-party certifying bodies accredited by NOP inspect plants and records to confirm compliance. These rules are not considered by NOP as a means to ensure safer, healthier or more nutritious foods. In fact, there is no regulatory distinction in the tolerable levels of pesticide, drug or other residues allowed in organic vs. conventional products (even though lower residues may in fact be a result). Rather, it is viewed as a confirmation of the organic production process, and the purchaser is left to his or her own determination as to whether the costs merit the perceived benefits.
Currently, "human-grade" claims on petfood labels are not allowed by most regulators. Part of the concern is that the claim is technically false, in that products containing meat and poultry ingredients derived from human food sources are not legally "edible" (by humans), since as soon as it left the human food facility it left USDA jurisdiction. People may falsely construe that the product is under continuous USDA inspection and hence safe for human consumption, neither of which is accurate. However, considering the relative costs of these types of products, some concerns expressed by regulators of intentional consumption by the poor is likely overestimated. A recent court case found in favor of the company making "human-grade" claims over a state feed control official that had denied registration of the product for distribution in that state. The repercussions of that ruling in that and other states is not known at this time.
Raw petfoods are a unique deviation from conventional petfoods. They typically contain a predominance of uncooked animal-source ingredients (meat or poultry, by-products, and bones), some vegetable materials, a few additives such as vitamins and minerals, and very rarely grains. Many people have very strong opinions about the merits of raw petfoods, either for or against. The truth may lay somewhere in the middle.
Proponents of raw petfoods attest to their nutritional superiority compared to their thermally-processed counterparts. However, there is little scientific study to support their contentions. The major concern on the opponents' side is microbial contamination. Even with good sourcing of ingredients, strict manufacturing hygiene, and proper storage and transport, there is always a potential risk. Although dogs and cats can suffer the consequences of pathogenic bacteria present in food, the real concern is to people handling the product. Since the storage and preparation areas, utensils, etc., that are used for human foods in a household are likely to be the same as to where the raw petfood is held, prepared or served, the need for proper sanitation is paramount.
FDA has issued guidance as to the manufacturing and labeling of raw petfoods. It suggests safe handling instructions similar to what appears on raw met and poultry products for human consumption under USDA authority. Perhaps its most useful suggestion in helping to ensure product safety is the judicious use of ionizing radiation to control pathogens. Because of mandatory irradiation labeling requirements and the niche of the consumer market to which raw petfood caters, that very helpful tool is grossly underutilized.
Other unconventional commercial petfoods
Vegetarian petfoods can range from absence of meat and poultry products to completely vegan formulations. Theoretically, diets to meet the nutritional needs of carnivores can be formulated without animal products, but it's not easy in practice. Analysis of the nutritional adequacy of several vegan products on the market, even those proclaiming to be complete and balanced, showed significant nutritional deficits (Grey et al., 2005). Palatability of products replete of animal-source ingredients must also be considered.
A form of petfood common in other countries but new to the US is, for lack of a better term, "fresh" pet food. These may appear similar to the salami-shaped soft-moist chub products, but unlike those products that are preserved with simple sugars and humectants, the fresh petfood must be kept refrigerated to prevent spoilage. They are cooked, processed similarly to cold cuts for human consumption, but the meat and poultry ingredients are complemented with vegetables or grains along with vitamins and minerals. However, because of their appearance and need for refrigeration, they are sometimes confused with raw petfoods.
One major petfood company is due to release a complete and balanced dog food in a compressed bone shape, which the dog chews like a typical treat product (only much bigger!). Essentially, it eliminates the need for a bowl to feed the animal.
Homemade pet diets
Although the feeding of human food scraps to dogs as the main source of nutrition has been a practice for millennia, the introduction of commercial petfoods has greatly diminished the custom. However, there has always been interest in homemade formulations by a segment of the pet owning public who are skeptical of the safety or wholesomeness of commercial products, especially after the recall this past year. At the same time, developing countries with growing middle classes may be recognized by a shift from homemade pet diets to commercial petfood products.
Convenience (or lack thereof) of home preparation is a deficit. That aside, the major concern is assurance of nutritional adequacy. Publications, web sites, and other sources abound with recipes that simply have not been shown by scientific means to be suitable for long-term feeding, and often recipes are obviously deficient at first glance. For those clients intent on feeding a homemade formulation, there are services offered by experts trained in nutrition that can offer complete and balanced recipes to meet the individual pet's needs.
Selected references and sources of information
Cowell CS, Stout NP, Brinkmann MF, Moser EA, Crane SW. Making commercial pet foods. In: Hand MS, Thatcher CD, Remillard RL, Roudebush P (eds). Small Animal Clinical Nutrition, 4th Edition. Topeka, KS: Mark Morris Institute, 2000; pp. 127-146.
Grey CM, Sellon RK, Freeman LM. Nutritional adequacy of two vegan diets for cats. J Amer Vet Med Assoc 225(11):1670-1675, 2004.