Lorrie Shaw / Contributor

For so many of us, our lives have come to encompass our pets. Co-existing with companion animals means a lot of things — how we care for them, the toys that they need and the important area of nutrition.

As Kelly Swanson, a University of Illinois animal sciences researcher tells it, when it comes to pet food, sustainability should be paramount.

But how realistic is the prospect? Swanson, who with The Nutro Co. (they produce pet food brands like Natural Choice & Ultra), propose that this area of sharing life with a pet can easily be made more sustainable.

Ingredients count

The pet food industry has grown substantially, and goodness, has it changed over the years. Walk into any pet store and you'll see shelves lined with high-end foods touting phrases like "organic," "human-grade ingredients" and "natural." The brand names even glow with references to their naturally-sourced ingredient profiles and how the food is formulated. Of course, the favorable whisper of how healthy a food is and the results that it promises to deliver are compelling.

One theory to help reduce the load on the planet requires thinking outside the box when it comes to the source of nutrients pets require to be healthy. The assertion has been made that they can be derived from broader choices in the food chain.

Case in point: protein.

Yes, pets need it to maintain their good health, and for the most part, that ingredient comes from meat — these days that's mostly chicken, beef, turkey and lamb. Buffalo and fish are other common sources, especially in higher-end brands.

Some companies promote formulas that have enhanced levels of protein, which for the vast majority of pets isn't even necessary.

It's been noted that the pet food industry is closely tied with the production of livestock and, in some respects, directly with the human food system, primarily because human-grade ingredients are used.

Animal-sourced protein is expensive to produce not only from a financial standpoint, but in terms of the environment as well. Animal protein requires more water and energy to produce than plant-based counterparts.

Much to the delight of many, some pet food companies are including more plant-based proteins in their ingredient profiles, like soy and legumes (peas) -- as well as newer-to-the-market sources like quinoa.

Vegetarian or vegan diets for pets have been popular in recent years, but not without some controversy, as I've written about in the past.

Dr. Tony Buffington, professor of veterinary medicine at The Ohio State University's Department of Veterinary Clinical Sciences, has pointed out that while canines, who are omnivores, can adapt more easily to a vegetarian diet. Cats, as obligate carnivores — meaning that the majority of their nutrition needs to be derived from animal sources — makes their nutritional needs are different.

The main caveat with feeding felines a vegetarian or vegan diet is that they usually become deficient in taurine — an amino acid essential for proper cellular function. Cats synthesize taurine at a lower rate than dogs, and it is depleted more quickly. Taurine deficiency can lead to problems with vision, and is associated with dilated cardiomylopathy, a type of heart disease.

Less is more

Swanson notes that another practice on the part of pet owners that is far from sustainable: the overfeeding of pets.

"They're being fed as much as 20 percent more than they need, so their health is poor, and you're wasting all that food," indicates Swanson.

"Especially with cats, it's very difficult."

Cats do not self-regulate well when it comes to food intake.

I couldn't agree more. Quite honestly, overfeeding is something that I see frequently and judging from the waistlines of many pets that I see, people are not getting the message when it comes to what's behind the cause of their furry and feathered friends' portly appearance.

Feeding less food is in itself a highly sustainable practice. In doing so, it has a secondary benefit: a fuller wallet.

Long term thinking

Could employing strategies like these increase the sustainability of pet foods in the future? Certainly. And that is one thing to really mull over, considering that pet owner ship worldwide is increasing, not only here in the United States.

One last thought of my own: pet overpopulation also works against the idea of sustainability as a whole. With so many homeless pets and the struggle to feed, house and care for them, it seems that the area of pet nutrition may be another area where it's important to meet the needs of the present and not put those needs of the future in peril.

Lorrie Shaw leads the pets section for AnnArbor.com. Connect with her on Google+ and follow her daily adventures as a professional pet sitter or email her directly.