Chapter 4 The Role of Nutrition in Canine Performance and Rehabilitation 77variability in terrain and incline versus decline.
Treadmill exercise reveals that there is a loss of
efficiency in energy utilization with increased
incline due to the need for vertical rise increas-
ing overall kcal expenditure. Larger dogs need
to exert more energy to break the fall that occurs
on decline (Taylor et al., 1972; Ordway et al.,
1984; Schmidt‐Nielsen, 1984). Uneven footing
or poor footing (snow and sand), as well as load
bearing result in increased energy expenditure
(Taylor, 1957).
Field studies examining energy expenditure
of working Greyhounds have shown that the
average 32–35‐kg Greyhound expends approxi-
mately 2050 to 2160 kcal per day. These studies
take into account the typical training regimen
for a racing Greyhound, which includes being
penned or caged with daily sprint training in
enclosed paddocks for approximately 30 min-
utes and two races a week (Hill et al., 1999,
2000). These findings translate to approxi-
mately 150–160 kcal/kg0.75. This relatively high
MER may be a reflection of the increased mus-
cle mass in Greyhounds. One would expect that
average agility dogs would have similar kilo-
calorie requirements for their proposed activi-
ties. However, recent evidence suggests that the
average competitive agility dog consumes
approximately 106 kcal/kg0.75 to maintain a
body condition of 4/5 out of 9 (J. Wakshlag,
unpublished findings).
Interestingly studies by Hill and colleagues
suggested that feed restriction during racing
from the normal of approximately 155 kcal/
kg0.75 body‐weight (BW) down to a restricted
regimen of only 137 kcal/kg0.75 resulted in
decreased racing times making mild feed
restriction advantageous (Hill et al., 1999). There
are numerous reports of caloric intake in rac-
ing sled dogs. Decombaz and colleagues (1995)
suggested an intake of only 2100 kcal/day dur-
ing an average of 79 km a day (228 kcal/kg0.75),
while Orr (1966) suggested an intake of approx-
imately 4400 kcal when pulling a heavy load
over ice for 32 km per day (270 kcal/kg0.75).
These discrepancies appear significant and may
be related to climate, housing, and activity in
and outside of the kennel. Additionally, these
estimates did not factor in changes in lean and
fat mass during these activities.
Two studies used double‐labeled water with
deuterium and^18 O (heavy oxygen) to assess
total oxygen loss via urine versus that gener-
ated and lost through respiration as CO 2. This
technique allows calculation of relative CO 2
loss, which is a rough estimate of total kilocalories
consumed since the only route for CO 2 genera-
tion is the ETC. Dogs running an average of 79
km a day over 8 days expended approximately
438 kcal/kg0.75 BW. However, the conditions
and temperature during the field experiment
were not reported (Decombaz et al., 1995).
A second study by Hinchliff and colleagues in
extreme racing conditions with dogs running at
a speed of approximately 7 km/h approxi-
mately 14 h per day over 5 days (total 490 km)
at temperatures between −10 and −35°C sug-
gested the kcal expenditure in 18 dogs aver-
aged 1052 ± 192 kcal/kg0.75 BW per day
(Hinchcliff et al., 1997b). This study and a more
recent study examining food diaries of mushers
suggests that metabolically these dogs would
need approximately 9000–13,000 kcal per day
to maintain body‐weight (Loftus et al., 2014).
This intake is nearly impossible, and therefore
many dogs in these conditions use body
reserves to meet the caloric demands.
Most clients with performance dogs are
acutely aware of their animals’ body condition
scores (BCS) and competitive body‐weights.
The traditional body condition scoring meth-
ods use a 5‐ or 9‐point system. The 9‐point sys-
tem has been validated through comparison
with dual X‐ray absorptiometry analysis
(Laflamme, 1997) and is preferred by the author
(Purina, 2012). Typically, clients with performance
dogs keep their dogs at a 4–5/9 BCS where ribs
are easily palpable, there is an obvious abdo-
men tuck, and when viewed and felt from the
top the spinous processes can be felt, while a
waist can be visualized. In athletic dogs, par-
ticularly Greyhounds, field trial, hunting and
sprint sled dogs, it may be more desirable to
have a BCS between 3 and 4. In this paradigm,
ribs can be visualized in shorter haired dogs,
the spinous processes and wings of the ilia are
prominent, but ample paralumbar musculature
extends between the wings of the ilia so that the
sacral spinous processes can be localized, but
do not protrude. Dogs in sprinting and inter-
mediate activity (10–30 minutes) need to be
lean to achieve ideal performance (Figure 4.5),
and restricted meal feeding is common. In endur-
ance activities where speed is not as important