If cats and dogs could grocery shop, they would naturally gravitate to the meat and seafood department because, from a biological standpoint, they are carnivores. This is even after thousands of years of domestication and many bowls of table scraps. “Their digestive systems are optimized to metabolize the natural nutrients present in muscle meat and organs,” says Sharon Durham, marketing communications manager, Ziwi USA, Overland Park, Kansas.

This puts some pet owners in a predicament, as many are modifying their own diets to be more plant based, heeding the recommendations of nutritionists, environmentalists and animal activists. This movement in the human food and beverage sector has pet owners exploring similar offerings for their furry friends.

When meat is optional

Dogs can exist on properly balanced meatless diets, though most would prefer not to, according to David Meeker, senior vice president of scientific services, National Renderers Association, Alexandria, Virginia. Cats, on the other hand, require meat products to be included in their diet due to their taurine requirement and inability to convert carotene to retinol. A vegan diet simply does not supply cats with the essential nutrients they need to be healthy.

“Cats have a simpler, shorter digestive tract with limited fermentative capacity to use plant-based ingredients,” says Gary Davenport, companion animal technical manager, ADM Animal Nutrition, a division of Archer Daniels Midland Company (ADM), Chicago. “While cats do have some ability to use plant-based ingredients, the long-term feeding of a strict vegan food is not biologically appropriate for cats due to their specific nutritional needs.”

That does not mean more plant-based ingredients cannot be included in a cat’s diet. Plant-based proteins may be used in combination with animal proteins to achieve a highly palatable, high-protein food or treat for both cats and dogs.

“Pet foods with higher content of plant-based ingredients provide a sustainable, ethical and environmentally friendly option to pet owners,” says Jennifer Adolphe, Ph.D., nutrition manager, Petcurean, Chilliwack, British Columbia. “Within the plant-based category, some pet foods are strictly vegan — containing no animal-based ingredients — while others are vegetarian and contain mostly plant-based ingredients.”

Compared to human food, pet food is unique because it is designed to be “complete and balanced.” This means all the nutrition a cat or dog requires is included in the food. “People consume a highly varied diet from day to day, which masks imbalances in nutrient availability and nutritional quality of a given meal,” Davenport says. “Dogs and cats, on the other hand, are generally fed the same food each day.”

If a pet’s food is not nutritionally complete, balanced and digestible, there may be serious health and wellness consequences. “Keep in mind that each nutrient in cat and dog food has a purpose,” says Patrick Luchsinger, marketing manager of nutrition and pet food, Ingredion Inc., Westchester, Illinois. “Without adequate nutrition, our pets would not be able to maintain muscle tone, build and repair muscles, teeth and bone, digest food properly, and fight off pathogens, which could lead to sickness.” As a result, pet foods tend to have a lengthy ingredient statement. This is true for animal- and plant-based formulations.

"Without adequate nutrition, our pets would not be able to maintain muscle tone, build and repair muscles, teeth and bone, digest food properly, and fight off pathogens, which could lead to sickness,” says Patrick Luchsinger, marketing manager of nutrition and pet food, Ingredion Inc.

Although Tampa, Florida-based Halo Purely For Pets uses whole meat, poultry and fish rather than “meat meal” in most of its pet foods, the company believes there are benefits to incorporating vegan dog food into their weekly diets. “None of the essential nutrients required by dogs are found exclusively in animal tissues. In animal nutrition, we really prefer to talk about nutrient requirements, as opposed to ingredient requirements,” says Dr. Sarah Dodd, a veterinarian with an advanced degree in plant-based nutrition who works with Halo. “As far as we know, dogs have no requirement for meat per se, instead, they have a requirement for nutrients that may be obtained from meat, or from other sources.”

“Many dog parents feed their dogs vegan either because they wish to extend their own vegan lifestyle to that of their companion animal, or because their dogs are experiencing allergic reactions to common meat-based dog food recipes,” she says.

Prioritizing protein

The movement toward using plant-based ingredients in pet food is mostly about using protein ingredients that are as sustainable as possible to meet the nutrient requirements of cats and dogs. Finding sustainable animal protein sources has become increasingly challenging because not only are humans competing for protein around the world, but now the pet food industry is competing as well.

Years ago, plant proteins were viewed as an inexpensive way to extend protein in both human and pet foods. Today, this could not be farther from the marketplace situation. “While they may be less expensive than meat, they are definitely not cheap,” Adolphe says. “From a formulator’s perspective, plant proteins have the advantage of being quite consistent in their nutrient content. Conversely, some animal protein ingredients, especially fresh meats and meat meals, can be highly variable in nutrient levels, particularly for fat, protein and minerals.”

This often makes plant proteins easier to work with. In addition, most pet foods are already supplemented with vitamins and minerals, so fortification is already part of the development process. With fortification, pet owners can be assured of consistent nutrient delivery to their companions.

“Protein is a predominant focus in human nutrition for muscle development and satiety, and this is being translated into the pet space,” says Melissa Machen, senior technical services specialist, Cargill Texturizing Solutions, Minneapolis. “There has been an explosion of new and reformulated pet products that focus on meat as the number-one ingredient. At the same time, we’re also seeing products with plant-based protein sources increasing in pet foods, mirroring the growing popularity of plant proteins in human foods.”

“As with humans, pets need protein sources that are complete, meaning they contain the required levels of all essential amino acids,” Machen says. “Amino acids are important for the organ and muscle health of the animal, along with many other growth functions. Soy protein is the only plant-sourced complete protein, based on amino acid profile, and can be used in pet foods to deliver high quality protein.”

Soy, peas and pulses, oh my

Soy ingredients can be used in pet food to add protein and functionality in extruded products, as well as various treat items. Soy is a cost-effective plant protein that is typically low in fat, which helps reduce oxidative flavor formation in shelf life.

“Pea protein is also gaining popularity in pet foods and treats,” Machen says. “While pea protein contains all the essential amino acids, it is not considered a complete protein because two of the amino acids, methionine and cysteine, are limiting. However, formulators can blend pea protein with a complementary protein source, such as rice, chickpea, soy or pumpkin. Rice is a common option as it has higher levels of methionine and cysteine to complement the pea protein. Pea and rice protein can be blended together in the right ratio to achieve a complete protein.”

Pulses, which include dry peas, lentils, chickpeas and beans, are nutritional powerhouses, packed with protein, fiber, vitamins and minerals. Pulses are versatile and serve as a flavor sponge. They complement all types of formulations, vegan and vegetarian, and pair well with animal-based proteins. “They also happen to be good for the planet with one of the lowest carbon footprints of almost any other food group,” says Tim McGreevy, CEO, US Dried Pea and Lentil Council, Moscow, Idaho. “Production of pulse crops has more than doubled in the past 10 years as demand for these nutrient-dense foods has risen.”

This increased production has been followed by a significant investment in processing plants that convert pulse crops into whole flour, protein, starch and fiber ingredients. Pulse ingredient manufacturers continue to build capacity to meet the growing demand for pulse crop proteins and ingredients. They are also investing in ways to enhance functionality and identify new uses.

“Some pulse ingredients, for example, can be utilized to partially or fully replace egg or dried egg in high-moisture, wet, canned applications, where binding and adhesion are desired functionalities,” Luchsinger says. Plant proteins and nutrient pre-mixes are often combined at contract blending facilities. This simplifies measuring and mixing at the manufacturing location.

For example, ADM has a new pre-mix facility in Effingham, Illinois. The company sources and blends standard, dry ingredients for bulk shipment to pet food and treat manufacturers. “These ingredient blends eliminate the need for additional bin space at the manufacturer, while reducing the number of bulk and micro ingredients that must be added during food and treat making,” Davenport says.

Neither a plant nor an animal

In addition to plants being a source of vegan protein, there’s also the emerging category of fungal proteins. Fungi are a type of eukaryotic organism. Others include microorganisms such as yeasts and molds, as well as more familiar mushrooms. From a biological standpoint they are neither plant nor animal; however, most consumers view them as being part of the plant kingdom.

Wild Earth Inc., Berkeley, California, a biotech pet food start-up, is rolling out its first product, a dog treat made with koji (Aspergillus oryzae), an eco-friendly, renewably sourced member of the fungi kingdom. Koji has umami-rich flavor; it mimics the taste of savory meat. It is a whole protein that provides all essential amino acids, along with omega fatty acids, digestion-boosting enzymes and prebiotics to support gastrointestinal microbiomes.

“We need new and alternative proteins to feed a growing global pet population, and also to minimize the environmental impact of feeding that growing population,” says Ryan Bethencourt, chief operating officer at Wild Earth. “Koji is ideal for dogs based on its nutritional profile and sustainability, and it is used by Michelin-star chefs to add gourmet flavor, so our dog taste testers loved these treats.”

Wild Earth cultivates koji, an ancient Asian protein, in fermentation tanks, and uses proprietary technology to optimize it for nutritional content, texture and flavor. “Our mission is to help pet owners feed their dog a varied diet that meets its complete nutritional needs while reducing the need for animal meats,” says Dr. Ernie Ward, chief veterinary officer at Wild Earth. “We don’t believe broad labels such as vegan or vegetarian adequately define our products. Our goal is to create the best pet food possible utilizing biotechnology.”

New plant proteins will continue to be identified, grown and purified into safe, high-quality ingredients for use in foods for both pets and their owners. Maybe someday there will be meals strategically designed to meet the nutritional needs of both at the same time, giving new meaning to family-sized portions.

Read more about product development, ingredients and formulation.