The Feeding Behavior of Dogs Correlates with their Responses to Commands

Abstract

Motivation is one of the most important factors in dog training. To generate motivation, people use various reinforcer mechanisms. In particular, many pet owners use food because it is simple and convenient. The aim of this study was to investigate the association between dogs' level of interest in food and their responsiveness to commands. Thirty-four dogs were divided into three groups based on their feeding patterns (Fast, Slow, and Leftover). The fast group (n=15) had the highest interest in food and showed a high response to commands when food was used as a reinforcer, rather than praise/stroking. The leftover group (n=6) showed the least interest in food and had a low reaction to commands, regardless of the reinforcer. In contrast, the slow group (n=13) had modest interest in food and maintained the same response to commands regardless of the reinforcer. Results of this study indicate that dogs' feeding patterns are indicative of their level of interest in food, and may be useful in determining the optimal training reinforcer. This can help dog owners improve their relationships with their dogs.

Full text

FULL PAPER Ethology
The Feeding Behavior of Dogs Correlates with their Responses to Commands
Yuta OKAMOTO1), Nobuyo OHTANI2), Hidehiko UCHIYAMA2) and Mitsuaki OHTA2)
1)Animal Life Solutions Co., Ltd., 16–6 Ibukino, Midoriku, Yokohama, Kanagawa 226–0028 and 2)Department of Animal Science and
Biotechnology, Azabu University School of Veterinary Medicine, 1–17–71 Fuchinobe, Sagamihara, Kanagawa 229–8501, Japan
(Received 19 January 2009/Accepted 25 August 2009)
ABSTRACT. Motivation is one of the most important factors in dog training. To generate motivation, people use various reinforcer mech-
anisms. In particular, many pet owners use food because it is simple and convenient. The aim of this study was to investigate the asso-
ciation between dogs’ level of interest in food and their responsiveness to commands. Thirty-four dogs were divided into three groups
based on their feeding patterns (Fast, Slow, and Leftover). The fast group (n=15) had the highest interest in food and showed a high
response to commands when food was used as a reinforcer, rather than praise/stroking. The leftover group (n=6) showed the least interest
in food and had a low reaction to commands, regardless of the reinforcer. In contrast, the slow group (n=13) had modest interest in food
and maintained the same response to commands regardless of the reinforcer. Results of this study indicate that dogs’ feeding patterns
are indicative of their level of interest in food, and may be useful in determining the optimal training reinforcer. This can help dog own-
ers improve their relationships with their dogs.
KEY WORDS: behavior, canine, commands, feeding, reinforcer.
J. Vet. Med. Sci. 71(12): 1617–1621, 2009
Operant conditioning has been popularly used in dog
training to teach an animal that its response to a command
has consequences [8]. The observation that the conse-
quences of a behavior can determine whether the behavior
will occur again led Thorndike to the ‘Law of Effect’ which
states that if a consequence is pleasant, the preceding behav-
ior becomes more likely. If a consequence is unpleasant, the
preceding behavior becomes less likely [11]. For example,
if a dog sits in response to the command ‘sit’ and then
receives a treat, and then this sequence is repeated, the dog
will establish a link between the command, the response,
and the treat. In this case, the dog’s response to the com-
mand has been positively reinforced by the treat [8]. There
are many types of reinforcer for dogs such as food, toys and
praise. Many dog owners have used food as reinforcer
because of its convenience.
When learning, motivation is one of the most important
factors that influences learned behavior. In other words,
learning might not occur without motivation [8]. Once a
behavior has been learned, it may not be performed unless
the animal is motivated to respond. A reinforcer serves to
provide motivation. There is variation among individuals in
the effectiveness of a reinforcer; for instance, some dogs are
motivated to learn with food, while others would prefer
toys.
The dog origin from wolves is well established from
genetic as well as behavioral and morphological data [2, 14,
15]. The digestive tract of wolf is specialized and able to
handle large quantities of food in a single meal — a distinct
advantage in a competitive feeding situation [12]. Although
the domestication process has altered the feeding behavior
of dog, some breeds still demonstrate a remarkable agility to
gorge, and will eat exceptionally large quantities of food
whenever it is available [12]. This characteristic may also
be influenced by gender, age, breed and dietary factors.
Several breeds of dogs have a reputation for being able to
consume large meals very rapidly, and it is possible that this
is the result of competitive feeding in the wolves from which
they were domesticated [1]. Certain breeds that have a high
propensity to gain weight, such as Cocker Spaniel, Labrador
Retriever, Dalmatian, Dachshund, Golden Retriever, and
Shetland Sheepdog may have a particularly high interest in
food [4, 7]. A dog has high interest in food and which has
been trained using food as a reinforcer, has difficulty in
switching to secondary reinforcer. Such dog sometimes
rejects the owner’s command when it knows its owner
doesn’t have food. While food is the convenient reinforcer,
it is difficult to build good relationship with the dog and
control it if the owner doesn’t understand his/her dog’s level
of interest in food.
The aim of this study was to examine the relationship
between dogs’ level of interest in food and their response to
the commands, as related to feeding pattern. Such a correla-
tion would suggest that identification of a dog’s feeding pat-
tern may contribute to the selection of a suitable reinforcer
and training strategy.
MATERIALS AND METHODS
Subjects: The subjects were 34 healthy dogs of 21 differ-
ent breeds (18 males and 16 females): 23 dogs were studied
at the World Ranch in Osaka, Japan, and 11 dogs were stud-
ied at the Murase Dogs Training Center in Kanagawa, Japan
(Table 1). All of the dogs were sexually intact and 12–96
months of age (mean 50.7  4.4 months, excepting one dog
*CORRESPONDENCE TO: OHTANI, N., Laboratory of Effective Ani-
mals for Human Health, Azabu University School of Veterinary
Medicine, 1–17–71 Fuchinobe, Sagamihara, Kanagawa 229–
8501, Japan.
e-mail: ohtani@azabu-u.ac.jp

Y. OKAMOTO, N. OHTANI, H. UCHIYAMA AND M. OHTA
1618
whose age was unknown). They were housed in individual
metal cages and provided with commercial dog food (Adult
Maintenance, Nutro Products Inc., CA, U.S.A.), according
to the industrial recommendation. Although their back-
ground (place of their birth, duration until they came to
facility, etc.) varied, all of them were kept at each facility for
at least one year. All dogs had been taught basic commands,
such as “sit” and “down”, by the staff at each facility using
the positive reinforcement technique [3, 9, 10, 13] and their
own food as the primary reinforcer and praise/stroking as
the secondary reinforcer. All of the procedures were
approved by the Animal Experiments Ethics Committee of
Azabu University.
Classification of the dogs according to their feeding pat-
tern: To classify the dogs, we recorded their normal feeding
behavior for ten minutes using a digital video camera (GSC-
R60, Toshiba, Japan). By measuring weight of food and
duration of feeding, the feeding speed (g/sec) and the
amount of food consumed per mouthful (g/chew) were cal-
culated. All dogs were divided into 2 groups; those who
consumed their food completely and those who only par-
tially consumed their food (Leftover). The dogs who com-
pletely consumed their food were then divided into 2 groups
according to whether they chewed every mouthful more
than once (Slow) or not (Fast). The dogs were therefore
divided into the three groups according to feeding pattern,
Leftover, Slow and Fast.
Experimental procedure: The outline of the experiment is
shown in Fig. 1. Dogs were presented the command of “sit”
every 5 sec for 5 min. Sessions were repeated 3 times with
3 min resting periods between each session. In Experiment
1, the dog’s daily food was used as the reinforcer. In Exper-
iment 2, praise/stroking were used as the reinforcer. The
praise was a verbal “good” while stroking the dog’s back
gently. Experiment 1 was conducted on all dogs first, then
after 2 to 3 weeks, Experiment 2 was performed. The exper-
iments were conducted in the dog’s familiar exercise yard
by a handler (male, 29 years, and accustomed to working
with dogs). The handler was not a stranger to any of the
dogs, but only made contact with dogs during the experi-
ments. When a dog responded to a command correctly, the
handler gave the dog a reinforcer immediately. When the
dog reacted incorrectly or did not show any response, the
handler did nothing until next command.
Behavioral evaluation: Whole sessions were recorded
using a digital video camera (GSC-R60, Toshiba, Japan).
The number of serial operant sequences of administration of
the command, response to the command and delivery of
reinforcer were counted as the frequency of correct
responses to the command. The period (seconds) during
which each dog gazed at the handler, which indicated dog’s
concentration, was also measured.
Statistical analysis: The correlation between the fre-
quency of correct responses to the commands and the length
of time spent gazing at the handler was calculated using the
Pearson product-moment correlation coefficient or the
Table 1. Profile of the subjects
Breed Sex Age Weight
(months)
Fast group
Brittany Male 18 15
Brittany Male 18 15
Dalmatian Male 95 29
Dobermann Female 72 31
Golden Retriever Female 60 27
Golden Retriever Male 38 22.5
Labrador Retriever Male 36 29
Labrador Retriever Male 36 31
Labrador Retriever Female 96 23
Labrador Retriever Female 12 23
Labrador Retriever Male 71 31
Labrador Retriever Male 46 25.5
Labrador Retriever Male 39 24
Newfoundland Female 66 36
Standard Poodle Male 13 21
Slow group
American Cocker Spaniel Female 53 10
Australian Shepherd Dog Male UN 17
Basset Hound Female 48 20
Border Collie Female 38 16
Clumber Spaniel Female 55 19
Flat-coated Retriever Male 78 24
Flat-coated Retriever Female 41 21
German Shepherd Dog Female 60 26
German Shepherd Dog Female 72 25
German Shepherd Dog Male 19 28
Golden Retriever Female 37 22
Rough Collie Male 19 25
Weimaraner Female 91 21
Leftover group
American Cocker Spaniel Male 77 8
English Cocker Spaniel Male 58 9
Greyhound Female 96 23
Jack Russell Terrier Male 17 5.5
Pyrenean Mountain Dog Female 46 23.5
Vizsla Male 52 21
UN;Unknown n=34
Fig. 1. Experimental procedure. Dogs were given the command to sit every five seconds for five minutes.
In Experiment 1, food was used as a reinforcer. In Experiment 2, praise/stroking was used as a rein-
forcer.

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FEEDING BEHAVIOR AND RESPONSE IN DOGS
Spearman rank correlation coefficient. The differences
among sessions in each group were analyzed using Bonfer-
oni/Dunn test in one-way factorial ANOVA. The differ-
ences between reinforcers were analyzed by Student’s t test
and p values <0.05 were considered significant using the
average of three sessions. Results are expressed as means 
SE.
RESULTS
According to feeding patterns, the thirty-four dogs were
divided into three groups: Fast (n=15), Slow (n=13) and
Leftover (n=6). There was no distribution bias according to
the facilities (data not shown). Feeding speed did not corre-
late significantly with the body size, in other words, with the
length and depth of the muzzle of the dog (data not shown).
Relationships between the feeding speed and the amount of
food per mouthful for each dog were shown in Fig. 2. There
was a significant positive correlation between them (rs=0.8,
p<0.05). Figure 3 shows the comparison of the frequency of
correct responses to the commands and the length of time
spent gazing at the handler in Session 1 using food (Experi-
ment 1, Fig. 3-a) or praise/stroking (Experiment 2, Fig. 3-b)
as the reinforcer. There were significant positive correla-
tions between the frequency of correct responses and the
length of time spent gazing at the handler (rs=0.9 (a) and 0.8
(b), p<0.05).
The comparison among groups in each session for Exper-
iment 1 is shown in Fig. 4. Over all of the sessions, the Fast
group showed significantly longer periods of gazing at the
handler than the Slow and Leftover groups (p<0.05). Dur-
ing Sessions 1 and 3, the Slow group exhibited a longer
duration of gazing at handler than the Leftover group
(p<0.01). The Fast and Slow groups correctly responded to
the command more frequently than the Leftover group
throughout the sessions (p<0.05).
The results of Experiment 2, using praise/stroking as the
reinforcer, are shown in Fig. 5. The Slow group showed sig-
nificantly longer periods of gazing at the handler than the
Leftover group (p<0.05). The frequency of correct
responses to the command in the Slow group was signifi-
cantly higher than that for the Leftover group (p<0.05).
In the Fast and the Leftover groups, the average period of
gazing (sec) at the handler of all sessions showed significant
differences between reinforcers [food vs. praise/stroking:
253.1  1.9 vs. 121.7  21.7, p<0.01 (Fast group); 99.5 
12.9 vs. 35.2  19.7, p<0.05 (Leftover group)]. The fre-
quency of correct responses (number) to the commands also
differed significantly between reinforcers [food vs. praise/
stroking: 54.5  0.4 vs. 26.1  4.4, p<0.01 (Fast group); 21.3
 2.2 vs. 6.5  3.0, p<0.05 (Leftover group)]. The Slow
group did not show significant differences between rein-
Fig. 3. The comparison between the frequency of correct
responses to the commands and the length of time spent gazing
at the handler during Session 1: a) food was used as a reinforcer
(Pearson product moment correlation coefficient: rank correla-
tion=0.9, p<0.05), b) praise/stroking was used as a reinforcer
(Spearman rank correlation coefficient: rank correlation=0.8,
p<0.05). Circles: Fast group; triangles: Slow group; squares:
Leftover group.
Fig. 2. Relationships between the feeding speed and the amount
of food per mouthful for each dog. There was a significant posi-
tive correlation between them (Spearman rank correlation coef-
ficient: rank correlation=0.8, p<0.05). Circles: Fast group;
triangles: Slow group; squares: Leftover group.

Y. OKAMOTO, N. OHTANI, H. UCHIYAMA AND M. OHTA
1620
forcers on the period (sec) (food vs. praise/stroking: 191.3 
4.1 vs. 174.4  24.7) and the frequency (number) (food vs.
praise/stroking: 50.0  0.9 vs. 40.6  3.2).
DISCUSSION
The present study demonstrates a correlation between
dogs’ responses to commands and their feeding patterns. As
shown in Table 1, the feeding speed (g/sec) and the amount
of food consumed per mouthful did not depend on sex, age,
or the dogs’ body size. On the whole, there was a significant
positive correlation between the frequency of correct
response to the command and the length of time that a dog
spent gazing at the handler, regardless of the reinforcer. In
Experiment 1, dogs in the Fast group, which did not chew
every mouthful, maintained high scores, even when the ses-
sion was repeated. This suggests that the Fast group could
maintain the operant response to the command when food
was used as reinforcer. On the other hand, it also suggests
that Fast group did not associate the primary reinforcer
(food) with the secondary reinforcer (praise/stroking), since
these dogs showed significantly lower scores when using
praise/stroking. In Experiment 2, their responses were
reduced from Session 1 to Sessions 2 and 3. Ten out of fif-
teen in this group were breeds that are vulnerable to obesity
[4, 7]. These data suggest that owners of these breeds
should be cautious about using food as the reinforcer in
training because of their high level of interest in food and
the excess intake of calories.
The Slow group, which achieved almost the same scores
as the Fast group with respect to the frequency of correct
response to the command, did not show any difference when
praise/stroking was used as reinforcer. This group sustained
appropriate responses to the command when praise/stroking
was used as the reinforcer. This result suggests that the
Slow group could take food as the primary reinforcer and
then associate that food with praise/stroking as the second-
ary reinforcer. Furthermore, it is suggested that this group
may be able to connect the reward to the work with the han-
dler, and consider this work to be pleasant. A scheme for
motivation of the Slow dogs is proposed to be ‘com-
mand=food=handler’. Therefore, we suggest that the Slow
group can be motivated by a wide variety of stimuli during
training with positive reinforcement. We predict that these
dogs would be easy to handle for the typical dog owner.
The Leftover group showed consistently low responses to
food and praise/stroking, and these reinforcers could not
motivate these dogs. Therefore, this study found that food
Fig. 4. The comparison among groups in each session of the length of time spent gazing at the handler (a) and
the frequency of correct responses to the command (b) in Experiment 1. * p<0.05 by Bonferoni/Dunn test in
one-way factorial ANOVA.
Fig. 5. The comparison among groups in each session of the length of time spent gazing at the handler (a) and the
frequency of correct responses to the command (b) in Experiment 2. * p<0.05 by Bonferoni/Dunn test in one-way
factorial ANOVA.

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FEEDING BEHAVIOR AND RESPONSE IN DOGS
might not be an adequate reward for this group. These dogs
appear to have difficulty connecting the reward with the sec-
ondary reinforcer. The Leftover group consisted of three
ancient breeds, Greyhound, Pyrenean Mountain Dog, and
Vizla. Although further studies are required, the process of
living with humans might have affected the feeding pattern
and interest in food of these dogs. Concerning the analyses
of training methods used on working dogs, Haverbeke et al.
[5] suggested that motivationally equivalent rewards might
need to be identified and given to dogs instead of food (e.g.
tug and retrieve games). Furthermore, Reid [8] insisted that
in any training situation, one must consider the motivational
state of the animal as well as the learning contingencies, and
the potential for competing motivations.
Even though there were some differences, all groups
showed lower scores for praise/stroking than those for food.
Secondary reinforcement is acquired through experience
[6], therefore all groups showed low responses to praise/
stroking. But perhaps we would have gotten different
results if the experiments were conducted by facility staff or
repeated by us. Although there might be the possibility that
the breed difference such as trainability, friendliness to
human, and sensitivity to stimuli affect dog’s responses to
commands, the further research would be needed in more
numbers of individual breeds.
In this study, identification of a dog’s feeding pattern was
a simple and effective way to evaluate its level of interest in
food. This may contribute to the selection of the optimum
reinforcer for each dog. Using the optimum reinforcer
should lead to better results in training and consequently a
better relationship between the dog and its owner.
ACKNOWLEDGMENT. This study was partially sup-
ported by a project grant (Creative Research Project, 2008)
awarded by the Azabu University Research Services Divi-
sion.
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