Two-pan and operant lever-press tests of dogs' preference for various foods

A comparison of paired- and multiple-stimulus-without-replacement preference assessments to identify reinforcers for dog behavior

Dogs may be relinquished to shelters and are unlikely to be adopted if they engage in problem behavior. A successful way to eliminate problem behavior is through training techniques based on behavioral principles. Obedience training with the use of positive reinforcement has been successful in treating problematic behavior by dogs. In order for this method to work, it is essential that the stimuli selected function as reinforcers. Preference assessments can be used to identify these potential reinforcers. A preference assessment is a systematic method used to identify stimuli that may serve as possible reinforcers by yielding preference hierarchies. Although preference and reinforcer assessments have been successfully used with humans, research with nonhuman animals is limited. Therefore, the purpose of the study was to compare the efficacy and efficiency of paired-stimulus preference assessment with a multiple-stimulus preference assessment. The results suggested that the results of both preference assessments corresponded with reinforcer assessments but that the paired-stimulus method was the most efficient.

How Dog Behavior Influences Pet Owner's Perceptions of Dog Preference for Dental Chews

American pet owners spend billions of dollars on food and treats so it is important to understand what products they want and what they think their dog would enjoy. This study analyzed video recordings of dogs engaging in dental chews in their home environment and compared the observed appetitive behaviors to owner preference and owner-reported dog preference. Overall, appetitive behavior differed significantly between some dental chews. Owner preference for the chews correlated significantly with dog appetitive behavior, but the effect was small (r (702) = 0.22, p = 0.001), whereas owner-reported dog preference correlated significantly with dog appetitive behavior and showed a moderate effect size (r (702) = 0.43, p = 0.001)-similar in magnitude to findings when parents are asked to report on their children's behavior. By merging objective behavioral observation of owner-recorded videos with their survey responses, we were able to preliminarily parse out what factors owners may use to assess preference and encourage the future use of in-home video recordings to better understand dog and owner engagement and interaction with pet products.

Food and Food-Odor Preferences in Dogs: A Pilot Study

Evaluation of food palatability and preference is of great importance to the pet food industry. One common technique for evaluating palatability is a 2-bowl test in which 2 products are offered simultaneously and food consumption is measured. This yields clear results with dogs trained to routinely conduct such comparisons, but it is less clear how this extends to untrained pet dogs. In addition, prior research indicates that olfaction is important in food preference, but methods for evaluating odor preference in canines are currently lacking. In this study, we developed a modified 2-bowl test for evaluation of food preferences in pet dogs with minimal training, and an olfactometer technique for the evaluation of odor preferences. In our 2-bowl procedure, we observed clear preferences among 4 commercial food products in 6 pet dogs. Across repeated testing, preferences strengthened, but the first evaluation accurately estimated the direction and significance of preference. In addition, dogs typically (89% of the time) consumed more of the food they chose first, suggesting they did not need to taste each food to choose. Our odor preference olfactometer assessment, however, did not reveal odor preferences other than that dogs preferred to sniff a food odor over clean air. Further work will be needed to identify methods of measuring odor preferences amongst food odors for dogs, but the modified 2-bowl test shows promise for further testing in pet dogs.

Assessing Food Preferences in Dogs and Cats: A Review of the Current Methods

Food is a major aspect of pet care; therefore, ensuring that pet foods are not only healthful but attractive to companion animals and their owners is essential. The petfood market remains active and requires ongoing evaluation of the adaptation and efficiency of the new products. Palatability-foods' characteristics enticing animals and leading them to consumption-is therefore a key element to look at. Based on the type of information needed, different pet populations (expert or naïve) can be tested to access their preference and acceptance for different food products. Classical techniques are the one-bowl and two-bowl tests, but complementary (i.e., operant conditioning) and novel (i.e., exploratory behavior) approaches are available to gather more information on the evaluation of petfood palatability.

Pet Food Palatability Evaluation: A Review of Standard Assay Techniques and Interpretation of Results with a Primary Focus on Limitations

Simple Summary

Palatability of pet foods is typically measured using a single-bowl or a two-bowl test. While these tests give a general understanding of the liking or preference of one food over another, opportunities exist for further method development.

Abstract

The pet food industry continues to grow steadily as a result of new innovative products. Quality control and product development tests for pet foods are typically conducted through palatability testing with dogs and cats. Palatability is the measure of intake of a food that indicates acceptance or the measure of preference of one food over another. Pet food palatability is most commonly measured using a single-bowl or a two-bowl assay. While these tests answer some questions about the animals’ perception of the food, there are many limitations as well. This review addresses some of these limitations and indicates opportunities for future research.

Assessing preference and reinforcer effectiveness in dogs

The paired-stimulus (PS) preference assessment has been shown to be effective in assessing preference with animal subjects, including dogs; however, evaluations on whether preferred stimuli would also function as reinforcers are lacking. The purpose of the current study was to evaluate the use of the PS preference assessment as a predictor of reinforcer effectiveness in eight dogs. The assessment was followed by concurrent and progressive ratio schedules to evaluate the reinforcer efficacy of food items. Results showed that the preference assessment predicted reinforcer efficacy for all subjects. Benefits of using this assessment with dogs are discussed.

A novel cognitive palatability assessment protocol for dogs1

Assessment of canine palatability is important for both the pet food and pharmaceutical industries; however, the current palatability assessment protocols are limited in their utility. The most common technique, the two-pan test, does not control for the satiating effects of food and may not be useful for long-term palatability analysis because nutritional or caloric characteristics of the diets may interfere with the results. Furthermore, the large quantities of foods consumed may be detrimental to the health of animals that do not self-limit their food intake. The purpose of this study was to determine whether a cognitive protocol could be used to determine food palatability in dogs. Five beagle dogs were trained on a three-choice object-discrimination learning task. After establishing object preferences, the preferred object was associated with no reward, a second object was associated with the dog's normal laboratory diet (Purina Agribrands Canine Lab Chow No. 5006; Agribrands Purina Canada, Inc., Woodstock, ON, Canada), and the third object was associated with a commercial (Hill's P/D; Hill's Pet Nutrition Inc., Topeka, KS) diet. In the discrimination-training phase, dogs were trained until they learned to avoid the no-reward object. They were subsequently given an additional 20 test sessions, which were used to determine food preference. In the reversal phase, which involved reversal learning, the object-food associations were modified, such that the object that was previously associated with Hill's P/D diet was now associated with the normal laboratory diet and vice versa. Once the dogs learned to avoid the no-reward object, they were tested for an additional 20 sessions. All subjects learned to avoid the no-reward object during the initial learning, and the number of choices to the object associated with the Hill's P/D diet was greater than the number of choices to the objects associated with the dry laboratory diet (P < 0.05) and no reward (P < 0.05), indicating a strong preference for the Hill's P/D diet. The object preferences were reversed in only three of five dogs when the food-choice associations were reversed, although the two phases did not differ significantly from one another. The protocol in the present study provides a robust measure of food palatability and circumvents many of the limitations associated with other palatability assessment techniques. The present protocol should be useful as a replacement or adjunct to other tests of palatability, but requires further validation by comparing the assessment of more similar and novel foods directly with other palatability tests.

An apparatus for studying operant activity of captive coyotes

We describe a portable apparatus designed to examine the free-operant food preferences of captive coyotes in their home kennels. Because lever-pressing for food access was the dependent variable, we measured food preference independently of food ingestion. Using successive approximation, we trained 8 out of 19 coyotes (42%) to use the apparatus. This percentage is similar to training rates for dogs. We used fixed and variable ratio schedules of reinforcement to further test 4 of the trained coyotes. All 4 produced response curves similar to those of other species on similar schedules of reinforcement.

Use of innate behaviors to evaluate sensory function in the dog

The need to evaluate sensory function in the dog is discussed. A group of techniques that use innate behaviors (species-typical behaviors) and are effective in the evaluation of sensory function of domestic animals are described. Techniques to measure olfactory, gustatory, auditory, and visual function are included.

Operant conditioning methodology in the assessment of food preferences: introductory comments

This paper provides a general introduction to the methodology used in the next three papers of this monograph to test dogs' food preferences. This "operant conditioning" methodology was developed in behavioral laboratories concerned with learning in animals. The logic of the methodology is described, some technical and practical aspects of the methodology are summarized, and its application in the hedonic-scaling of qualitatively different foods is discussed. The relation between this new methodology and the traditional two-bowl preference test is reviewed.

Studies in canine olfaction, taste and feeding: a summing up and some comments on the academic-industrial relationship

The authors discuss two principal points. First, what appear to be contradictory findings in the feeding studies in this monograph can be resolved by clarifying two terms: palatability and preference. Second, some of the work in the monograph resulted from an academic and industrial relationship. This relationship was judged mutually beneficial and productive. The primary benefits are discussed along with what are considered the key ingredients for a successful joint venture.

Demonstration of basic concurrent-schedules effects with dogs: choice between different amounts of food

Two experiments studied the ways dogs perform on concurrent operant schedules when choosing between different amounts of food. Experiment 1 allowed six dogs to choose between obtaining different amounts of food available for responding on two levers. Across phases of the experiment, the food amounts were available in four different weight-to-weight ratios, 1:1, 2:1, 3:1, and 4:1. The operant schedule was concurrent VI 60 sec VI 60 sec. The results showed that the dogs "undermatch" when the ratio of their responses on the two levers is plotted against the ratios of the amounts of food they produced by responding on those levers. When the response ratios were recomputed to include only those lever-presses that occurred outside the change-over delay (C.O.D.) period, the severity of undermatching was reduced, and the data averaged across all six dogs showed a matching function. Experiment 2 studied the effect of varying the duration of the C.O.D. when the dogs chose between food-amounts in a 3:1 weight-to-weight ratio. The number of times the dogs alternated between responding on the two levers per session was inversely related to the duration of the C.O.D., but the approximation to matching seems little affected.