Taste as a tool

Pet food trends may come and go, but one timeless factor is taste. If a pet won’t eat the food, it doesn’t matter how healthy or novel the recipe is.

This is why veterinary researchers have spent decades gathering data about food palatability and investigating why pets have certain taste preferences.

Results from this research are helping veterinarians ensure their patients eat and enjoy their food, even those with dietary restrictions, food sensitivities, and health conditions that affect appetite.

Factors in palatability

“Whether a dog or cat likes a food primarily depends on the smell as a first hurdle,” said Timothy J. Bowser, PhD, a food process engineer in the Biosystems and Agriculture Engineering Department at the Oklahoma State University R.M. Kerr Food and Agriculture Products Center.

The center is dedicated to discovering, developing, and delivering technical and business information that supports the growth of value-added food and agricultural products and processing, including pet food.

“If the way the food was processed negatively impacts the odor, then pets will not favor it as highly as other products,” Bowser said. "They probably won't even try it.”

Hill's Pet Nutrition’s scientists serve as a human sensory panel to describe aromatic attributes to compare different aroma profiles. Descriptors such as “fatty” and “meaty” are used to create an aroma profile called the aromagram. Each aromagram acts as a unique aroma identifier for a particular pet food. Hill’s then conducts preference testing with animals at its Pet Nutrition Center (PNC) to compare these profiles and better understand which ones are liked or disliked by dogs and cats.

Olfaction and taste in cats and dogs are different from those in people because animals are far more sensitive, said Dr. Joseph Wakshlag, a nutritionist and professor in the Department of Clinical Sciences at Cornell University College of Veterinary Medicine.

Palatability, however, is about more than just smell and taste, says Dr. Karen Shenoy, U.S. chief veterinary officer at Hill’s, as some pets prefer certain forms, textures, or flavors.

Aesthetics can impact how easily dogs and cats pick up and chew food. Research has shown that dogs and cats have different preferences for kibble size, shape, and texture, and this research was used to develop Hill’s Prescription Diet ON-Care/ONC Care Canine and Feline kibble.

The data shows that cats prefer kibble that is crispy and made into shapes such as discs and triangles. In comparison, dogs prefer larger kibble as well as kibble with a chewier texture or wet food that has been warmed up.

According to a 2022 AFB International study, flat disc and cross or star shapes had the best palatability scores for cats. The flat disc shape also has more surface area, which can assist with palatability and adherence of palatants. These are additives added to pet food to make it more appealing.

Dr. Wakshlag explained that a pet’s enjoyment of a food is directly related to palatants, which comprise about 1%-3% of the pet’s diet. The natural flavorings added to many pet foods have a liquid or dry palatant from fermented ingredients.

Digestibility is another factor in pet food preference.

“Digestibility depends on many factors, but the food must be primarily composed of elements that can be broken down by the activity of the animal’s digestive system,” Bowser said. “That includes physical and chemical treatments such as chewing, enzymes, temperature, liquid, and mixing.”

The quality of ingredients, fiber content, and processing can all affect digestibility, according to Dr. Wakshlag. He explained that because humans, dogs, and cats are monogastrics, they can get appropriate nutrition from a variety of sources such as grains and meat. However, dogs and cats have different protein requirements.

“Dogs are omnivores with great metabolic plasticity like humans, while cats are considered carnivorous due to their metabolism,” Dr. Wakshlag said.

Determining a pet’s preference

As learning more about taste preferences among pets has taken on greater importance, research efforts have similarly advanced. For example, the Science of Taste is Hill’s proprietary, evidence-based approach to taste technology that helps ensure pets enjoy the form, flavor, aroma, and consistency of their food.

Much of the work in this area is done at Hill’s Pet Nutrition Center (PNC), a 176-acre nutritional research and product development campus in Topeka, Kansas, that includes the Small Paws Innovation Center—a $30 million, 25,000-square-foot facility, which opened in late 2021.

In all, the PNC is home to more than 1,000 animals and their foremost job is, well, eating food. About 150 dogs and 150 cats at the center regularly participate in preference tests for different formulas.

For example, using a two-bowl testing method, proprietary feeders automatically measure the amount of food each dog or cat consumes at every meal. Intake amounts are statistically analyzed at a 95% confidence level to determine which food the pets prefer.

The two-bowl test is excellent for determining which food pets prefer, however, it does not explain what may be driving that choice.

In response, Hill’s scientists developed behavior lexicons to identify what pets do when they are eating. These lexicons cover the interactions such as the approach to the bowl, the food selection process, and the types of bites a pet takes. Based on pet behaviors, scientists can rate the level of arousal, enthusiasm, and pleasure or displeasure regarding the food.

Pet food for health concerns

“Taste takes on additional importance in dietetic or therapeutic foods, as many clinical conditions can lead to reduced appetite, emphasizing the urgency to provide foods the pet will readily consume to support health,” said Melissa Vanchina, director of product design at Hill’s.

Hill’s Prescription Diet pet foods have species-specific nutrition customized for digestive issues, weight management, food and environmental sensitivities, dermatology issues, urinary challenges, kidney disease, and joint concerns.

When a pet owner chooses not to feed commercial diets, veterinary professionals can design home-prepared diets for pet ailments. Dr. Wakshlag explained that many nutritionists use formulation software packages to control nutrients for a variety of clinical indications. “That is the bread and butter for most clinical nutritionists that I know,” Dr. Wakshlag said.

“One of the most important assumptions for pet foods is that they should be a complete, balanced diet that meets all of the pet's needs, like energy, vitamins, minerals and fiber,” said Oklahoma State’s Bowser. “It is extremely important that this assumption is met, since the sole, or main, diet of many pets is the commercial pet food that they receive.”