Primates
DOI 10.1007/s10329-016-0541-3
ORIGINAL ARTICLE
A new method of walking rehabilitation using cognitive tasks
in an adult chimpanzee (Pan troglodytes) with a disability: a case
study
Yoko Sakuraba1,2 • Masaki Tomonaga1 • Misato Hayashi1
Received: 15 December 2015 / Accepted: 15 April 2016
Ó Japan Monkey Centre and Springer Japan 2016
Abstract There are few studies of long-term care and
rehabilitation of animals which acquired physical disabilities in captivity, despite their importance for welfare. An
adult male chimpanzee named Reo at the Primate Research
Institute of Kyoto University, developed acute myelitis,
inflammation of the spinal cord, which resulted in impaired
leg function. This report describes a walking rehabilitation
system set up in a rehabilitation room where he lives. The
rehabilitation apparatus consisted of a touch monitor presenting cognitive tasks and a feeder presenting food
rewards at a distance of two meters from the monitor, to
encourage him to walk between the monitor and the feeder
repeatedly. Initially, Reo did not touch the monitor,
therefore we needed adjustment of the apparatus and procedure. After the habituation to the monitor and cognitive
tasks, he started to show behaviors of saving food rewards
without walking, or stopping participation to the rehabilitation. Finally it took seven phases of the adjustment to
determine the final setting; when the monitor automatically
displayed trials in 4-h, AM (1000–1200 hours) and PM
(1400–1600 hours) sessions through a day, Reo spontaneously walked from the monitor to the feeder to receive
rewards, and returned to the monitor to perform the next
trial. Comparison of Reo’s locomotion in a no-task period
and under the final setting revealed that the total travel
distance increased from 136.7 to 506.3 m, movement patterns became multiple, and the percentage of walking
& Yoko Sakuraba
[email protected]
1
Primate Research Institute, Kyoto University, 41-2, Kanrin,
Inuyama, Aichi 484-8506, Japan
2
Japan Society for the Promotion of Science, 5-3-1,
Kojimachi, Chiyoda, Tokyo 102-0083, Japan
increased from 1.2 to 27.2 % in PM session. The findings
of this case study suggest that cognitive tasks may be a
useful way to rehabilitate physically disabled chimpanzees,
and thus improve their welfare in captivity.
Keywords Chimpanzee Physical disability Walking
rehabilitation Animal welfare Cognitive task
Introduction
The Primate Research Institute (PRI) of Kyoto University
studies chimpanzee’s cognition and perception using
computer experiments of settings (Matsuzawa 2003, 2006).
One adult male chimpanzee, named Reo, developed acute
transverse myelitis and had difficulty moving all parts of
his body except his head. The PRI staff attempted various
methods of care and massage therapy for Reo (MiyabeNishiwaki et al. 2010; Hayashi et al. 2013). As a result of
these efforts, Reo developed good arm movement and
could use hanging ropes and a bar to lift his body with his
arms, and could also move his legs a little. However, his
walking ability was impaired compared with intact chimpanzees because the bones of the hip and knee joints were
deformed during the period of intensive medical and
physical treatment of paralysis and pressure ulcers.
Good physical and psychological health are important
for the welfare of nonhuman animals in captivity (FAWC
2009; Hosey et al. 2013; Maple and Perdue 2013). In the
1970s, the Farm Animal Welfare Council (FAWC) proposed five freedoms, including freedom from pain, injury,
and disease which were accepted in many facilities
worldwide. Therefore, animals with signs or symptoms of
accidents, injuries, or diseases require medical/veterinary
care, intensive care, or euthanasia (FAWC; Hosey et al.
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Primates
2013). There has been abundant research on the methodology of medical care and euthanasia for animals (e.g.,
Leach et al. 2004; Miller and Fowler 2012). Applicable
knowledge and technical expertise are necessary for
appropriate management after the first period of intensive
care, particularly in animals that remained impaired.
Antilla et al. (2013, unpublished) and Dallaire et al. (2012)
have studied captive animals with disabilities; however,
there are few reports and little research on long-term care
and rehabilitation of disabled animals in captivity, despite
their importance for animal welfare. The World Association of Zoos and Aquariums (WAZA) argues that euthanasia should only be carried out when all other options
have been investigated and the decision is made for the
benefit of the animal (WAZA 2003). Moreover, there are
many species including chimpanzees that are on the
endangered species list and should therefore be protected to
whatever extent possible.
The CHIMPANZEE (Pan troglodytes) CARE MANUAL
which was published by the Association of Zoos and
Aquariums in association with the AZA Animal Welfare
Committee (2010) mentions ‘‘Chimpanzees should never be
housed alone for any extended period of time unless it is
deemed to be necessary for the physical or psychological
well-being of that individual’’. Thus, it can be said that the
final goal for Reo is ‘‘social reintegration’’. To achieve this
goal, we thought that the first step was to rehabilitate his
impaired hind-limbs by encouraging him to walk when
moving around his enclosure. Only using his upper body to
move can lead to health problems such as; a weakened lower
body, contracture of the muscles and joints in the legs,
overall decreased activity and obesity. Such health problems
also lead to worse psychological welfare (Rees 2011).
There have been several studies on walking rehabilitation in humans with various methods including the use of
parallel bars (e.g., Pillar et al. 1991), a treadmill (e.g.,
Hesse et al. 1999), gait orthosis (e.g., Bernardi et al. 1995),
robots (e.g., Siddiqi et al. 1994), and other combinations of
techniques (e.g., Felici et al. 1997). The effectiveness of
these methods has been evaluated using measures of
functional ambulation as indices of performance (e.g.,
Hoffer et al. 1973), walking ability, walking speed, walking distance, and cadence (e.g., Holden et al. 1984; Cunha
et al. 2002). In addition, for the rehabilitation to be successful, a self-management program (e.g., exchanging
ideas regarding problem solving, goal setting, or outcome)
is important (Jones 2014), and it is said that ‘‘improving
quality of life (QOL)’’ and ‘‘social reintegration’’ are one
of the final goals and purposes of rehabilitation (World
Health Organization 1981). In human patients with
acquired physical disabilities such as Reo, for instance,
constraint-induced therapy is one of the methods used to
encourage stroke patients to use disabled parts of the body
123
(Miltner et al. 1999). Evaluators instruct patients to walk a
specific distance as fast as possible to assess walking speed
(Cunha et al. 2002) and caregivers discuss and decide goals
and schedule to maintain the patient’s motivation (Jones
2014).
However non-human animals have many differences in
physical size, shape and strength as well as their ability to
understand and act upon verbal and/or non-verbal instruction. In addition, chimpanzees in particular, have very
strong upper bodies to support their weight when climbing
and moving through the trees (Takemoto 2004), so it is
dangerous for caretakers to interact with them directly. For
these reasons, we believe it is safer and more efficient to
encourage chimpanzees to participate in their own movement rehabilitation. In PRI, chimpanzees participate in
cognitive experiments voluntary. Reo also participated in
these experiments when he was a juvenile (Tomonaga et al.
1991; Fushimi 1994), therefore cognitive experiments
could be a good tool for rehabilitation of movement
without the use of force. In order to assess this, we focused
movement and locomotion patterns using well-established
observation methods in of both wild and captive chimpanzees. This report presents the implementation of a new
method of walking rehabilitation and evaluation in a
chimpanzee with hind-limb disability.
Methods
Chimpanzee
Reo is 1 of 13 chimpanzees (P. troglodytes) living in two
large sun rooms and one semi-natural outdoor compound
(700 m2) at the PRI (Matsuzawa 2003, 2006). He was
found lying on the ground of one of the sun rooms on the
morning of September 26, 2006; he was 24 years old. The
cause of this incident was acute transverse myelitis, which
resulted in Reo being unable to move his body below the
neck. He was isolated in a cage (130 9 80 9 150 cm) to
allow veterinary care, and received 24-h intensive care for
the first 2 months. He lost weight, and pressure ulcers
appeared (Miyabe-Nishiwaki et al. 2010). The staff provided him with medical care and massage therapy as well
as an improved bed to allow easier movement, a low-repulsion mattress to distribute his weight, and ropes and bars
to grasp, and encouraged him to change positions regularly.
Through these interventions, Reo began to move his arms.
10 months after the onset, he succeeded in raising his body
and sitting up by himself; subsequently, he was able to sit
for longer periods, and his physical functions and pressure
ulcers gradually improved. He gained weight and the
muscles of his forelimbs became strong, which made it
more difficult to provide therapy directly. However, the
Primates
encourage brachiation. Benches, which were made of
wooden logs, were attached 20 cm from the acrylic-board
wall and 30 cm above the floor. In addition, a puzzle feeder
and other feeders to support rehabilitation of the fingertips
were attached in the room. The position of these items was
regularly changed, and items were added or removed,
according to his usage. A video camera (SONY, model no.
DCR-TRV2) was set outside the rehabilitation room to
continuously record Reo’s behavior. An invisible infrared
light (model no. S8120-160-C-IR) was used for night
recording.
Reo’s daily schedule included certain routine events. At
0830 hours, a staff member came into the room, turned on
the light, and gave Reo his breakfast (approximately 400 g
of fruit and vegetables). Cleaning was conducted once in
the morning. At approximately 1200 hours, another staff
member provided lunch (approximately 600 g of fruit,
vegetables, and monkey chow with AS, by ORIENTAL
YEAST CO., LTD.). At approximately 1700 hours, another
staff member provided dinner (approximately 600 g of
fruit, vegetables, and monkey chow). There were 24–28
staff members caring for Reo, including graduate students.
Reo was exposed to other flexible scheduled events during
the day, such as food-based enrichment, playing with
humans, and training. Reo also underwent irregular
extension rehabilitation sessions wherein a caregiver and a
veterinarian performed rehabilitation by massaging his feet
and playing with him in the same room (Hayashi et al.
2013). Occasionally caregivers made opportunities that
some chimpanzees visited the room and interacted with
Reo through a mesh wall.
staff continued to provide environmental enrichment (e.g.,
toys and a touch monitor to watch video clips) and new
therapeutic measures (see Miyabe-Nishiwaki et al. 2010;
Hayashi et al. 2013). Moreover, Miyabe-Nishiwaki et al.
(2010) evaluated this process from onset to recovery from a
veterinary aspect (weight, nutrition, and method of treating
pressure ulcers), and Hayashi et al. (2013) evaluated the
recovery of regaining an upright posture from lying down
from a behavioral aspect. In 2009, Reo was moved from
the cage to a rehabilitation room.
Rehabilitation room
Human
area
Bed
a
180
Doors
Bench
180
Iron bars
Ceiling
a
280 cm
Chimpanzee
area
Swivable
partition
120
Platform
Concrete wall
Fig. 1 Final layout of the
rehabilitation room. White
represents the area used by
humans, and grey represents the
area used by the chimpanzee.
a Thin lines represent walls
made of acrylic board and iron
frames, bold lines represent
walls made of concrete, and
dotted lines represent wire grid
walls or partitions
Wire grid wall
Reo was moved from the small cage to a large rehabilitation room (Fig. 1) in April 2009 (Miyabe-Nishiwaki et al.
2010; Hayashi et al. 2013). In this room, he could hear the
loud voices of other chimpanzees and the sound of wall
drumming but could not have visual contact.
The room had three types of walls: concrete, wire grid,
and acrylic board attached to an iron frame (Fig. 1a), which
separated the humans from Reo. The floor area was
approximately 10 m2, and the distance from the floor to the
ceiling was 2.8 m. The floor was made of polyvinyl resin,
and the whole ceiling was covered with iron bars. One
platform, a quarter sector with a radius of 120 cm, which
was made of concrete, was placed at a height of 95 cm
from the floor. On the opposite side of the room, there was
a bed with a base made from polyvinyl chloride pipe,
which was covered with a low-repulsion mattress. Bars,
ropes, and rubber ropes were attached to the ceiling to
allow Reo to lift himself, to hang by his arms, and to
Acrylic board
40
cm
80
Iron frame
60
60
30
Drain
Basement
Floor
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Primates
Apparatus
Observations
On November 4, 2009, we installed the experimental
apparatus, a touch monitor and a feeder, in a corner of the
rehabilitation room (Fig. 2). The touch monitor (model no.
LCD-AD172F2-T supplied by IO-DATA, Ishikawa) was
used to present cognitive tasks. We fitted the monitor in an
acrylic case (40 9 42 9 20 cm; Fig. 2a) and attached it to
an acrylic board at a height of 60 cm above the floor. The
universal feeder (model no. BUF-310 supplied by Bio
Medica, Osaka) to present food rewards was installed
approximately 200 cm from the monitor. The feeder
deposited the food rewards into a food box (Fig. 2b), which
was attached to an acrylic board at a height of 30 cm above
the floor. The maximum number of food pieces placed in
the feeder was 100. The food (apple, carrot, sweet potato,
and monkey chow) was cut into pieces of approximately
two grams each to fit into a slot on the round feeder.
We adopted a visual search task to encourage self-motivation because he already experienced the task. In this
cognitive task, Reo was initially required to touch the start
key, which would call up the search display containing
three or four images. One of these images was called a
target stimulus, and was different from the other stimuli
(cf., Tomonaga 2001, 2008). If Reo touched the target
stimulus (correct response), a chime sounded and one piece
of food fell from the feeder. If he selected another stimulus
(incorrect response), a buzzer sounded, and food did not
fall into the food box. In setting up the apparatus and the
cognitive task, we intended Reo to walk to the feeder to get
a reward after a correct response, then return to the monitor
to perform the next trial, and repeat this process without
human encouragement.
We attempted to evaluate his movement, focusing on
distance and pattern, by examining the 24-h video
recordings. The observation method we used was time
sampling (Martin and Bateson 2007) per 10 s. Walking
distance was calculated as the sum of the distance that
Reo moved in horizontal and vertical directions in 10 s.
Movement pattern was classified into two major categories: use of hind limbs to provide primary locomotion
(‘‘walking’’) and use of the upper body, such as arms and
mouth (‘‘activity of the upper extremity’’). We further
defined three patterns under ‘‘walking’’—walking with
physical support, proto-knuckle walking, and hip-supported bipedal walking—and two patterns under ‘‘activity
of the upper extremity’’—brachiation and climbing and
descent (Table 1).
Routine care and experimental conditions used in this
study were conducted in strict accordance with animal use
guidelines recommended by the Primate Research Institute
of Kyoto University’s Guide for the Care and Use of
Laboratory Primates, Third Edition (2010). In addition, we
monitored his condition and took medical care if it was
needed.
Fig. 2 Experimental setup.
a Touch monitor in an acrylic
case attached to the wall.
b Universal feeder and food box
attached to the wall at a distance
of 200 cm from the monitor
Results
Response and feedback
Precise settings were adjusted by taking into account Reo’s
responses observed during each phase of the adjusting
process.
a
Monitor
Feeder
20
a
30
b
55
Acrylic board
and case
30 cm
Bolt
12
55 cm
40
b
13
40
55
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12
Primates
Table 1 Ethogram of locomotion
Category/pattern
Definition/detail
Walking
Walking with physical support
Walks on the floor holding ropes, grid wall, or benches with the hands or arms to support the weight
Proto-knuckle walking
Walks on the floor using arms to move and support the weight like a crutch
Hip-supported bipedal walking
Walks on the floor by swinging the body using only hind limbs and hips without the support of the arms
Activity of upper extremity
Brachiation
Moves horizontally in the space by hanging from ropes and bars attached to the ceiling and swinging
only using the arms
Climbing and descent
Moves vertically in the space by hanging onto ropes and grid walls using the arms
Phase 1
Phase 2
Phase 3
Phases
4, 5
On the first day we introduced the setting Reo
could not touch the monitor easily, and he
seemed fearful of the device. We simplified the
task from visual searching to touching one
image only and actively encouraged him
through verbal and gestural instruction to
touch it. This habituation took 7 days, and he
walked to the food box after every trial
Subsequently Reo began to save rewards in the
food box by performing several trials
consecutively without moving toward the food
box. We increased the interval time between
each trial from 5 to 20 s to encourage food
retrieval after every delivery, and this behavior
decreased as a result
We judged that the task—touching an image
once—had become easy for Reo and changed
the task to touching images twice displayed on
the monitor until he had sufficiently adapted to
this phase
On the evening of November 26, the task was
changed to visual searching. We also set that
the inter-trial interval (ITI) at 10 s (Phase 4)/
15 s (Phase 5) (after a correct response) and at
5 s (after an incorrect response)
The cognitive tasks were presented throughout
the day to promote walking, and we provided
food rewards on the feeder constantly. At
times, Reo stopped participating in the
rehabilitation program even though the food
rewards were still available, and sometimes his
legs or feet seemed to hurt or grow tired.
Considering this situation, we limited the time
of the rehabilitation sessions.
Phase 6
Phase 7
These adjustments took 5 days during which
time Reo did not receive any tasks. We set the
computer and touch monitor to automatically
start and stop displaying tasks at two
designated times during the day. The start and
end of the cognitive tasks were signaled by
music, and the sessions took place for 2 h
during the morning (1000–1200 hours, AM
session) and afternoon (1400–1600 hours, PM
session) between his meals. The maximum
number of food rewards was 100 per session
After the adjustment Reo began to participate
spontaneously in the rehabilitation without
human intervention when the music signaled
the start of the session. During rehabilitation
sessions, he walked 200 cm to obtain a food
reward after a correct response in a trial and
200 cm back to select a response in the next
trial (Fig. 3)
In sum, the final settings and schedule for the rehabilitation program were as follows: The cognitive task was a
visual search task, the interval between correct trials was
15 s, and the rehabilitation sessions took place at
1000–1200 and 1400–1600 hours every day. These final
settings and adjustments lead him to behave as we had
intended. The phases and process of adjustments are shown
in Table 2.
Movement analysis
We analyzed the recorded footage during the 5 days of
Phase 6 (non-task period of 16–20 December) and Phase 7
(second to sixth day of the final task setting, 22–26
123
Primates
Fig. 3 Photographs taken during a single trial. a Reo touched the
monitor and responded to the task. b If the response was correct, a
piece of food fell into the food box and he walked to obtain the food.
c He took the food. d He travelled back to the monitor. e He waited
until the monitor showed the next task and repeated the steps from
(a) to (d)
December) (Table 2), considering the relation of time
passage. We compared total distance walked and the
locomotion patterns between Phase 6 and Phase 7 during
1400–1600 hours. Total distance walked had increased
from 136.7 (Phase 6) to 506.3 m (Phase 7) (Mann–Whitney
U test; p \ 0.01; Fig. 4). Regarding locomotion patterns
(Fig. 5), ‘‘walking’’ increased significantly from 1.2 (Phase
6) to 27.2 % (Phase 7) (Mann–Whitney U test; p \ 0.01,
U = 0), and all three patterns of walking increased significantly; ‘‘walking with physical support’’ increased from
0.4 to 4.1 % (Mann–Whitney U test; p \ 0.01, U = 0),
‘‘proto-knuckle walking’’ from 0.8 to 2.7 % (Mann–
Whitney U test; p \ 0.05, U = 2), and ‘‘hip-supported
Table 2 Process of adjustment
123
Phase
Period
Task
ITI(s)
Rehabilitation
hours
One touch
5
Every time
1
11/4–11/21
2
11/21–11/23
3
11/23–11/26
Two touch
4
11/26–12/11
Visual search
5
12/12–12/15
15
6
12/16–12/20
(No rehabilitation)
7
12/21– (ongoing)
Visual search
20
10
15
Limited 4 h in a
day
bipedal walking’’ from 0.0 to 20.4 % (Mann–Whitney
U test; p \ 0.01, U = 0). On the other hand, ‘‘activity of
the upper extremity’’ showed no significant difference
(from 13.7 to 8.5 %, Mann–Whitney U test; ns, U = 5).
Neither individual pattern showed a significant difference
either: ‘‘brachiation’’ changed from 12.2 (Phase 6) to 7.4 %
(Phase 7) (Mann–Whitney U test; ns, U = 4), and
‘‘climbing and descent’’ changed from 1.6 (Phase 6) to
1.1 % (Phase 7) (Mann–Whitney U test; ns, U = 7).
Discussion
Apparatus
100
300
200
100
20
0
Phase 6
0
Phase 7
**
Walking
15
Phase
10
6
Phase
**
7
5
*
0.0
0
Brachiation
Climbing &
descent
With support Proto-knuckle Hip-supported
bipedal
Fig. 5 Locomotion pattern in 5 days of ‘‘Phase 6’’ (non-task period
of 16–20 December) and ‘‘Phase 7’’ (second to sixth day of the final
task setting, 22–26 December) of walking rehabilitation. Error bars
are standard error. **p \ 0.01; *p \ 0.05 (Mann–Whitney U test)
Motivation
400
**
Activity of
upper extremity
500
**
40
20
600
80
60
25
addition, Tomonaga (2010) published a column discussing
Reo’s personality, and Inoue-Murayama et al. (2006) categorized his personality according to questionnaire results
and gene analysis and determined that he is of a nervous
disposition. It is said that animals show different explorative personality traits and responses to novel experiences
(e.g., environmental enrichment) depending on age, sex,
genetics, and individual variation (Mench 1998). The
above mentioned factors might have contributed to the fear
that Reo showed toward the apparatus in the initial phase.
Fortunately, we were able to adjust the settings so that we
could still train him. This result suggests that we have to
carefully consider the present needs of each individual
animal when constructing testing apparatuses or study
formats, regardless of previous experience.
Total travel distance (m)
Percentage of average of locomotion (%)
The PRI has established fundamental principles regarding
use of a computer and touch monitor to study cognition in
chimpanzees (Matsuzawa 2003), and Reo had already
undergone cognitive experiments in the studies of
Tomonaga et al. (1991) and Fushimi (1994) when he was a
juvenile. Because of this past experiences, we had initially
predicted that it would be easy for him to perform the
rehabilitation, however he seemed to fear touching the
monitor. This might have been due to (a) the long gap of
time since his first experience with the system, and (b) the
influence of his personality. He had experienced the cognitive experiment approximately 20 years prior (Fushimi
1994). Beran et al. (2000), and Ueda and Tomonaga (2012)
have reported that some chimpanzees have long-term
retention capabilities for approximately 20 years. In
Percentage of average of locomotion (%)
Primates
-100
Fig. 4 Percentage and distance travelled in 5 days of ‘‘Phase 6’’
(non-task period of 16–20 December) and ‘‘Phase 7’’ (second to sixth
day of the final task setting, 22–26 December) of walking rehabilitation. The bar graph shows the percentages of locomotion (left yaxis, %), and the line graph shows total distance travelled (right yaxis, m). Error bars are standard error. **p \ 0.01 (Mann–Whitney
U test)
In humans, it is reported that the use of games and virtual
reality has led to high levels of motivation (Reid 2002;
Bryanton et al. 2006; Betker et al. 2007), and in chimpanzees, it is reported that cognitive experiments can be
used for environmental enrichment (Morimura 2006; Clark
2011; Yamanashi and Hayashi 2011). In the present study,
Reo participated voluntarily in the rehabilitation sessions
without human interference after the final adjustment.
Therefore, we reasoned that the use of cognitive tasks with
explicit feedback would be successful for maintaining his
motivation, and could be useful for long-term care. Yet, it
is difficult to infer his emotional state during rehabilitation.
In the first day of the 5 days analyzed in Phase 7, Reo
started the rehabilitation task 13 minutes after the signaling
the start of the rehabilitation task was played. This may be
explained by an initial failure to associate the music with
the start of the cognitive tasks (on subsequent days he
123
Primates
started after 1 to 2 minutes of the music being played). On
the other hand, this initial delay may also have reflected his
emotional state. In addition, he sometimes vocalized
excitedly upon hearing the starting music. In the future, this
will be evaluated further along with research into the social
aspects of his motivation and welfare.
During the adjustment period, we attempted to encourage Reo walk as much as possible by adding food
throughout the day and sometimes vocal instruction. It is
possible that these prolonged rehabilitation sessions could
have led to boredom or excessive strain, or having had too
much food might have been a contributing factor. The time
limits applied in the present study enabled him to concentrate on the task at hand as well as to maintain a certain
level of physical strain as training. However, we have to
maintain his motivation for a long period, therefore we
have plans to control and evaluate his behavior in terms of
cognitive enrichment in the future such as changing the
difficulty of tasks and quality of food rewards.
Walking practice
We considered that this rehabilitation method encouraged
Reo to practice walking because his locomotion pattern and
distance moved improved during the rehabilitation sessions. At times when no rehabilitation was being performed, Reo moved using mainly his upper body because
of the impaired function of his legs and the recovery of his
arm muscles. In human cases, constraint-induced therapy is
one of the methods used to encourage stroke patients to use
disabled parts of the body by binding or restricting the
intact body parts (e.g., Miltner et al. 1999). This rehabilitation method could be used in this study to successfully
circumvent the ethical and welfare issues associated with
forcing non-human animals not to use their intact body
parts.
Regarding Reo’s locomotion pattern using the hind
limbs, hip-supported bipedal walking increased, but protoknuckle walking was not predominant, as is the case in
intact chimpanzees. Reo’s flat back as a result of being
bedridden in the small cage may have also been a factor
in the predominance of hip-supported bipedal walking
because it was difficult for him to flex his back and put
his hands to the floor. Nevertheless, proto-knuckle walking did start to appear after introduction of the rehabilitation sessions. We also observed a dramatic increase in
total distance moved. Before the last adjustment of the
rehabilitation protocol, Reo moved only 100 m in 2 h, but
after the adjustment, this distance increased to approximately 500 m. Thus, with this rehabilitation method, Reo
was encouraged to voluntarily partake in functional
rehabilitation and to increase the amount of walking
practice.
123
Conclusion and future vision
This study successfully applied a new method of walking
rehabilitation using cognitive tasks to a chimpanzee with
hind-limb disabilities. In particular, total distance walked
increased, and the chimpanzee voluntarily participated in
the process. Though Reo initially appeared fearful of the
touch monitor and stopped several times during the walking rehabilitation sessions, careful adjustments resolved
this problem, leading to the conclusion that personality and
physical condition need to be considered when designing
and adjusting a rehabilitation program. In addition, this was
the first successful rehabilitation method to encourage
walking and customized for a chimpanzee, Reo. In the
future, we will need to continue rehabilitation exercises,
and discuss goals for his continued improvement and wellbeing.
Chimpanzees are an endangered species (Oates et al.
2008), and they are important for research and education
because they are one of the species most closely related to
humans (The Chimpanzee Sequencing and Analysis Consortium, 2005). The method presented in this research can
also be used to help other disabled chimpanzees in captivity. Furthermore, if we adopt one of the main purposes
and goals in human rehabilitation—improving QOL and
social integration (WHO 1981)—the novel rehabilitation
program described here may be one way of improving
QOL, and the first step towards the social reintegration of
animals with disabilities. Although the present report is a
case study, cross-species rehabilitation research, including
on humans, may lead to other methods for improving
animal welfare in the future.
Acknowledgments We would like to thank Prof. Testuro Matsuzawa
for supervising and financially supporting the present study, as well as
the Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology (Nos. 20002001,
24000001). We are also grateful to Kiyonori Kumazaki, Akino
Watanabe, Akihisa Kaneko, Shohei Watanabe, Takako MiyabeNishiwaki, and Norihiko Maeda for taking initiative in Reo’s daily
care and medical treatments, and for offering continuous support
throughout this study. Special thanks are owed to the following
people who also participated in Reo’s daily care, and provided us with
invaluable advice and information: Masayuki Tanaka, Tomoko Imura,
Ikuma Adachi, Shinya Yamamoto, Gaku Ohashi, Yuko Hattori,
Tomomi Ochiai, Toyomi Matsuno, Makiko Uchikoshi, Tomoko
Takashima, Etsuko Ichino, Koshiro Watanuki, Akemi Hirakuri, Sana
Inoue, Laura Martinez, Takahisa Matsusaka, Fumito Kawakami,
Chloe Gonseth, Tadatoshi Ogura, Yoshiaki Sato, Takaaki Kaneko,
Fumihiro Kano, Christopher Martin, Etsuko Nogami, Suzuka Hori,
Yasuyo Ito, Mai Nakashima, Yumi Yamanashi, Yena Kim, Mari
Hirosawa, Akiho Muramatsu, Lira Yu, Sou Ueda, Yoshiki Kurosawa,
Duncan Willson, Gao Jie, Hirohisa Hirai, Munehiro Okamoto,
Kiyoaki Matsubayashi, Takashi Kageyama, Juri Suzuki, Koki
Nishiwaki, Atsushi Yamanaka, Akiyo Ishigami, Yoshiroh Kamanaka,
Masamitsu Abe, Mayumi Morimoto, Naoko Suda, Takayoshi Natsume, Seitaro Aisu, Rui Hirokawa, Hanako Sasaki, Sakiko Kuramoto,
Yasushi Furuhashi, Yui Fujimori, Shizuka Godjali, and Kogami
Primates
Takase from the PRI; Koji Ohata from the Graduate School of
Medicine of Kyoto University; Keisuke Hirami of Kawamura Gishi
Corp.; and Mitsuo Tagami of Osaka Rosai Hospital. Support for this
study was provided by the Primate Research Institute of Kyoto
University, a Grants-in-Aid for Scientific Research from the Ministry
of Education, Culture, Sports, Science and Technology (No.
23220006, 26540063 and 15H05709 to MT, No. 19700245, 23700313
and 15K00204 to MH); Benesse Corporation; and Research Fellowships of the Japan Society for the Promotion of Science for Young
Scientists (No. 13J00801 to YS).
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