What did we want to find out?
Much research within the field of canine cognition is based upon the assumption that dogs favour certain food rewards over others. Previously reported methods of assessing such preferences involve measuring:
- The amount of food consumed within a set time period by an individual (it is generally accepted that the food consumed in the greatest quantity is preferred by the individual).
- How hard an animal is prepared to work in order to access a food reward (it is generally accepted that the harder an animal is prepared to work, the more they prefer the reward on offer).
However, both of these methods are limited in terms of their application. There is the potential for animals to become satiated and/or get bored of the task, and some tasks require extensive training before the animal is able to complete them. As a food preference test is often used prior to starting a study, animals that are full or tired are problematic as they are less likely to perform optimally during testing.
We were interested in developing a new method of assessing food preference that aimed to overcome these problems; thus developing a test that was both quick to carry out and reliable, and that did not involve feeding dogs large amounts of food.
How did we do this?
A variety of breeds and ages of dog were represented both across owned pet and rescue populations. Twenty owned pet dogs, recruited from the dog database “PetsCanDo” (9 male, 11 female; mean age 6.35 years), and 24 rescue dogs, available for re-homing at the North Lincolnshire Centre of Jerry Green Dog Rescue, UK (19 male, 5 female; mean age 4.40 years) completed the study.
Each dog sampled 10 ml of two food types; one considered “high” value and one “low” value, based on the nutritional com-position of the foods. Immediately afterwards, 20 ml of each food type was placed in two separate, but identical, bowls inaccessible to the dogs (see pictures).
Dogs were given one minute off lead to explore, and the amount of time that they spent investigating each of the inaccessible food bowls was recorded.
The order of initial sampling of food (high or low value) and location of the food in relation to the dog during preference testing (left or right) were pseudo randomized. Owned dogs, only, received a repetition of the test with the position of the foods swapped, to assess the influence of side bias and test consistency within subjects
What did we find?
Regardless of test order or food position, owned dogs spent significantly more time investigating the high value food in comparison to the low (F1,19= 32.236, p<0.001). Likewise rescue dogs spent significantly more time investigating the high value food (t= 3.225, df=23, p=0.004).
Our results suggest that this is a quick, reliable and robust method of determining a preference between foods in both res-cue and owned dogs that does not require any training and avoids both fatigue and satiation.