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■ABSTRACT
Astudy was conducted to evaluate the influ-
ence of diet on hunting performance of English
pointers during the quail-hunting season in
southwest Georgia. Twenty-three trained dogs
were assigned to two commercially available di-
ets (i.e., Diet A = Eukanuba®Premium Perfor-
mance Formula, The Iams Company, Lewis-
burg, OH; Diet B = Diamond®Premium Adult
Dog Food, Diamond Pet Foods, Meta, MO).
Results showed that dogs fed Diet A main-
tained or gained weight and body condition
throughout the hunting season while dogs fed
Diet B lost body weight and body condition (P
<.05). Dogs fed Diet A demonstrated superior
hunting performance (P<.05) compared with
those fed Diet B based on total finds per hunt
and on the number of birds located per hour of
hunting. All blood variables were within nor-
mal ranges for adult healthy dogs throughout
the season. These results imply that diet can af-
fect the overall performance of hunting dogs
and should provide useful information to train-
ers, handlers, and clinicians who areconcerned
with promoting the best performance and
health in hunting dogs and other canine ath-
letes.
■INTRODUCTION
Hunting with dogs for sport or in competi-
tive events is a popular pastime in the United
States. The breed or type of dog that is used
varies with the type of game that is hunted as
well as the terrain and distances that are cov-
ered. Regardless of these differences, most
hunting workinvolves several hours of en-
durance activity interrupted with short periods
of intense running or sprinting. If a dog is
hunted often during a season, the major nutri-
tional concerns are feeding to promote optimal
performance and providing enough calories to
maintain body weight (BW). Weight loss is
common in dogs that are hunted daily, espe-
cially if weather conditions are harsh.1In addi-
tion, warm and humid weather conditions in
some areas of the country can significantly im-
pact a hunting dog’s ability to work and may
adversely affect food intake and the ability to
fulfill energy requirements.1
The nutrient needs of canine athletes have
received increased attention in recent years, re-
sulting in improved understanding of the
changes associated with athletic conditioning
in this species. The majority of published re-
ports havestudied racing greyhounds, endur-
Effect of Diet on Hunting Performance
of English Pointers
Gary M. Davenport, PhD
Russell L. Kelley, MS
Eric K. Altom, PhD
Allan J. Lepine, PhD
Research and Development Division
The Iams Company
PO Box 189
Lewisburg, OH 45338
Veterinary Therapeutics •Vol. 2, No. 1, Winter 2001
ance sled dogs, or dogs exercising on treadmills
in a laboratory setting. 2–5 Much less is known
about the nutritional needs of other types of
working dogs, which include, but are not lim-
ited to, dogs used for hunting, herding, obedi-
ence competitions, agility events and tracking
tests, and helping the disabled. For each of
these categories, the intensity of training and
amount of physical work that the dog is re-
quired to do can vary considerably. Regardless,
working dogs typically have increased energy
needs compared with normal adult dog main-
tenance requirements.1The magnitude of this
increase and the best way to supply both ener-
gy and other essential nutrients to working
dogs arenot known. To examine the influence
of diet on hunting performance, a study was
conducted with a group of trained English
pointers fed two commercial dog foods during
an entirequail-hunting season.
■MATERIALS AND METHODS
T
wenty-three adult English pointers housed
at a hunting plantation in southwest Georgia
were selected for the study. The dogs were al-
lotted into two experimental groups based on
age and gender. Group A comprised 6 females
and 4 males, with a mean age of 5.3 years
(range: 1.3 to 11.0 years); group B comprised
9females and 4 males, with a mean age of 5.1
years (range: 1.1 to 10.7 years). No littermates
were used in this study. Furthermore, no infor-
mation on the previous hunting performance
of these dogs was available to allocate them to
the respectiveexperimental groups. Therefore
allocation based on overall hunting perform-
ance was considered completely randomized.
The dogs weresubsequently assigned to two
professional handlers who wereemployed by
the plantation. These handlers were responsi-
ble for the daily careand management of the
dogs throughout the study. Handler 1 was re-
sponsible for a total of 14 dogs representing
both groups, while handler 2 was responsible
for a total of 9 dogs. These handlers were
blinded to the specific diet each dog received
during the season. Each dog was housed in an
individual 6 ft ×20 ft run and had continuous
access to water.
Groups A and B were assigned to be fed one
of two commercial diets.1The major ingredi-
ents, nutrient content, and caloric distribu-
G. M. Davenport, R. L. Kelley, E. K. Altom, and A. J. Lepine
11
TABLE 1. Major Dietary Ingredients of Commercial Diets Fed to
English Pointers During the Quail-Hunting Season
Diet A Diet B
Chicken Chicken byproduct meal
Chicken byproduct meal Ground corn
Cornmeal Wheat flour
Ground grain sorghum Chicken fat (preserved with mixed tocopherols)
Fishmeal Brewer’s rice
Chicken fat (preserved with mixed tocopherols) Beet pulp
Ground whole grain barley Fish meal
Dried beet pulp Egg product
Natural chicken flavor Flaxseed
Dried egg product Poultry digest
Brewer’s dried yeast Brewer’s dried yeast
Flax meal Minerals and vitamins
Minerals and vitamins
12
tions of each dog food are reported in Tables 1
and 2. The nutrient content of each diet re-
flects results from laboratory analyses conduct-
ed on representative samples of each diet using
Association of Official Analytical Chemists
procedures.6These diets were fed exclusively to
the dogs for 8 weeks before the start and then
throughout the quail-hunting season. The
dogs were fed once daily during the study and
did not receive any additional supplements or
treats at any time. Total aldehyde levels within
each diet were monitored throughout the study
to assess diet quality and possible changes due
to oxidative rancidity. Results showed that no
oxidation occurred, implying that the quality
of both diets was maintained throughout the
hunting season. All dogs had been fed Diet B
for two consecutive years beforethe initiation
of this study.
Dogs were initially offered amounts of food
calculated to maintain BWand body condition
based on the National Research
Council recommendation for esti-
mating daily metabolizable energy
(ME) requirements (ME = 200
BW0.67)where BW is expressed in
kilograms and 200 is an activity
constant for very active dogs.1,7
Handlers were instructed to adjust
the food allotment of individual
dogs as needed to maintain BW
and body condition during the
hunting season. The decision to
adjust the food allotment was at
the sole discretion of the handler.
Although individual food intake
could not be measured during this
study, food consumption was
monitored for each group on a
monthly basis based on the num-
ber of 40-lb bags of food con-
sumed during that period. Visual
observations by the handlers re-
vealed that daily food refusals were negligible
during the hunting season, which would not af-
fect the food consumption estimates.
All dogs weresubjected to the normal train-
ing and hunting program of the plantation as
shown in Figure 1. In southwest Georgia, the
quail-hunting season extends from mid-No-
vember through Februaryand is usually pre-
ceded by2months of individual training and
physical conditioning. During each hunting
session, a total of 8 dogs were typically used on
arotating basis (4 braces of 2 dogs each) to en-
sure that rested dogs were hunting. This stan-
dardapproach used by handlers during the
hunting session maximizes the number of
finds, or points, indicating the presence of
quail. In this study, the selection of the dogs
for hunting and the amount of time they were
allowed to hunt were based on the discretion of
the two handlers. Throughout the season, the
handlers, who were blinded to the dietary
Veterinary Therapeutics •Vol. 2, No. 1, Winter 2001
TABLE 2. Nutrient Content and Caloric Distribution
of Commercial Diets Fed to English Pointers During
the Quail-Hunting Season*
Nutrient Diet A Diet B
Protein (%) 31.2 26.1
Fat (%) 21.4 17.2
Crude fiber (%) 2.1 3.7
Moisture (%) 6.7 8.3
Ash (%) 6.6 6.7
Carbohydrate (%) 31.9 38.0
Calcium (%) 1.19 1.5
Phosphorus (%) 0.97 1.07
Calcium:Phosphorus 1.23 1.40
Gross energy (kcal/kg) 5120 4660
Metabolizable energy (ME, kcal/kg)†4470 4210
Protein (% of ME Calories)†28.1 25.4
Fat (% of ME Calories)†43.1 37.6
Carbohydrate (% of ME Calories)†28.8 37.0
*Nutrient content was determined by laboratory analyses and is ex-
pressed on an as-fed basis.
†Metabolizable energy content (ME) and caloric distribution were calcu-
lated using the protein, carbohydrate, and fat content and the modified
Atwater factors 3.8 kcal/kg, 3.8 kcal/kg, and 8.5 kcal/kg, respectively.
treatments, recorded the following informa-
tion for individual dogs: dates and total time
hunted, number of finds, number of flushes,
general attitude of the dog, and reasons for ces-
sation of hunting (e.g., fatigue, lack of interest,
injury). These data were used to calculate the
overall hunting performance of each dog by ex-
pressing their total number of finds per total
hours hunted during the hunting season. All
hunting was suspended from December 18th
through December 31st.
Licensed veterinarians, who were also blind-
ed to the dietary treatments, collected blood
samples and conducted physical examinations
at the initiation of the training period before
dogs were switched to the test diets (Septem-
ber) and at the initiation (November) and ter-
mination (March) of the hunting season.
Blood samples werealso collected beforeand af-
ter a simulated hunt in November and March
to evaluate metabolic responses during a con-
trolled 40-minute exercise period. Blood sam-
ples were obtained via jugular puncture using a
1.5-inch, 22-gauge needle fitted with a splash-
guard. Samples werecollected into appropriate
venous blood collection tubes for subsequent
hematology, serum chemistry, and thyroid
analyses. Blood samples (excluding the hema-
tology tube) were separated by centrifugation
(1600 ×gfor 15 min) within 30 minutes of
collection. The resulting serum and plasma
werestored in labeled microcentrifuge tubes at
4oCfor overnight shipment to a commercial
diagnostic laboratory(Antec Diagnostics, Inc)2
for analysis. All samples weresubjected to stan-
dard veterinarydiagnostic assays at the labora-
tory.
Body weights and subjective stool scores
werealso obtained weekly. Subjectivestool
scoring was conducted using a 5-point scale: 1
=liquid; 2 = soft, no shape; 3 = soft with shape;
4=firm (ideal); 5 = extremely dry. Body con-
dition and skin and coat health were subjec-
tively evaluated in September, November, and
March to coincide with the initiation of the
training and hunting seasons and the termina-
tion of the hunting season, respectively. Body
condition was scored using a 5-point scale: 1 =
thin; 2 = underweight; 3 = ideal; 4 = over-
weight; 5 = obese. Skin and coat evaluations
G. M. Davenport, R. L. Kelley, E. K. Altom, and A. J. Lepine
13
Figure 1. Schedule of activities during the training, conditioning, and hunting periods.
Baseline Samples
• Physical examination
• Body condition
• Skin and coat evaluation
• Blood sample
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May
Preseason Samples
• Physical examination
• Body condition
• Skin and coat evaluation
• Simulated hunt with
pre- and posthunt blood
samples
Postseason Samples
• Physical examination
• Body condition
• Skin and coat evaluation
• Simulated hunt with
pre- and posthunt blood
samples
Training and
Conditioning
Quail-Hunting
Season
14
included subjective assessments of skin dander
and epilation and coat shedding, shine, unifor-
mity, density, and softness. Individuals blinded
to the specific dietary assignments conducted
the subjective evaluations for body condition
and skin and coat health.
Because performance in a warm and humid
environment is an important consideration for
hunting dogs in the southern United States, a
temperature–humidity index was computed
for each day using weather data obtained from
alocal television station. This index was calcu-
lated using the day’s high temperature and rel-
ative humidity to provide an indication of po-
tential heat stress. The formula for computing
this index has been previously reported.8For
the purposes of this study, mild, high, and se-
vere levels of heat stress were represented by the
values 23.5 to 26, 26.0 to 29.0, and >29.0, re-
spectively.
All statistical analyses were conducted using
the general linear model procedure of the Sta-
tistical Analysis System.9For statistical analysis
of BW, body condition, and hunting perform-
ance data, the hunting season was divided into
six 2-week hunting periods. Total times and
duration of hunting, number of finds, and
finds per hour were calculated on an individual
dog basis for each 2-week period because all
dogs were not hunted equally during each pe-
riod. Despite unequal usage during the hunt-
ing season, each dog was allowed to hunt at
least one time during each 2-week period.
These performance data were subsequently an-
alyzed using a statistical model that included
the main effects for diet and hunting period
and their interaction. A significant period ef-
fect (P<.01) for total times hunted and total
hours hunted reflected the unequal usage of
dogs during the hunting season. Despite the
period-specific differences, the diet ×period
interaction was not statistically different for
any variable. Therefore, only diet effects arere-
ported for each period and as an overall mean
for the entire hunting season. For the blood
components, the main effects of exercise
(hunting) and diet, and their interaction, were
evaluated on serum metabolites in the blood
samples collected before and after the simulat-
ed hunts. These hunts were conducted at the
pre- and postseason time points. Pre- and post-
season results were not compared directly to
determine possible seasonal changes in the
serum metabolites. For all performance and
blood variables, differences among treatment
means were assessed by least-squares mean sep-
aration when the respective F-test for the Type
III sums of squares was significant (P< .10).
For all variables, arithmetic means and their re-
spective standard deviations are reported for
each treatment group.
■RESULTS
All dogs in the study remained healthy and
consumed typical amounts of food throughout
the hunting season. No differences in daily
food consumption wereobserved throughout
the season with daily consumption ranging
from 22.8 to 31.2 g/kg for dogs fed Diet A and
23.8 to 30.5 g/kg for dogs fed Diet B. For the
season, daily food consumption of dogs fed
Diet A and Diet B averaged 27.3 and 26.4 g/kg
of body weight, respectively. Dogs fed Diet A
maintained or gained weight and body condi-
tion throughout the hunting season, while
dogs fed Diet B lost BW and body condition
(P<.05; Figures 2 and 3). As a result, BW and
body condition scores at the conclusion of the
hunting season werehigher (P<.05) for dogs
fed Diet A compared with those fed Diet B.
Dogs fed Diet A demonstrated superior
hunting performance (P<.05) compared with
that of dogs fed Diet B based on total finds per
hunt and the number of birds located per hour
of hunting (Figures 4 and 5). These significant
differences in hunting performance (P< .05)
Veterinary Therapeutics •Vol. 2, No. 1, Winter 2001
werenot caused byincreased hunting frequen-
cy or longer hunting duration. Hunting fre-
quency during each 2-week period of the sea-
son averaged 3.9 and 3.6 hunts for dogs fed
Diet A and Diet B. The most frequent use oc-
curred during the last 2 weeks of the season
when both groups hunted an average of 6.7
times within 14 days. The dura-
tion of hunting was equal for both
groups, averaging 3.0 hours over
all of the 2-week periods, with
ranges of 1.7 to 5.1 hours/period
for Diet A and 2.0 to 5.6
hours/period for Diet B. Dogs
spent more total time hunting
during the final 2-week period of
the season (5.1 and 5.6 hours for
Diet A and Diet B, respectively).
The heat index was rated as high
or severe based on the tempera-
ture–humidity index for 9 days
during the hunting season (Figure
6). On each of these days, dogs fed
Diet A maintained their superior
performance based on more finds
per hour compared with dogs fed
Diet B. Similar performance re-
sponses were also observed during
periods of mild heat stress.
Chemical profile and complete
blood cell count results indicated
no major diet-induced changes in
the health status of the dogs dur-
ing the hunting season. The values
for all blood variables were within
the range considered to be normal
for adult healthy dogs throughout
the study. However, several statisti-
cally significant differences oc-
curred that might have physiologic
significance for hunting dogs. Re-
gardless of diet, the 40-minute
bout of hunting during the presea-
son period resulted in significant increases in
triglycerides, aspartate aminotransferase (AST),
osmolality, blood urea nitrogen (BUN), hema-
tocrit, and thyroxine; and decreases in serum
values for phosphorus and chloride (P< .10;
Tables 3 and 4). A significant (P<.10) inter-
action between diet and exercise (hunting) oc-
G. M. Davenport, R. L. Kelley, E. K. Altom, and A. J. Lepine
15
Figure 3. Body condition scores of English pointers fed two commercial
diets during the quail-hunting season.
*diet effect, P<.05.
Figure2. Body weight of English pointers fed two commercial diets dur-
ing the quail-hunting season.
*diet effect, P<.05.
Baseline Preseason Postseason
11/20–12/4 12/5–12/18 1/1–1/15 1/16–1/29 1/30–2/12 2/13–2/16 Overall
Mean
***
**
16
curred for several parameters in the preseason
period. Dogs fed Diet A had significantly re-
duced values for γ-glutamyl transferase (GGT)
and fibrinogen in response to hunting. Con-
versely, hunting was associated with reductions
in serum calcium and mean corpuscular hemo-
globin concentration (MCHC) in dogs fed
Diet B and an increase in serum
levels of total protein, creatinine,
BUN:creatinine, sodium, hemo-
globin, red blood cells, and triio-
dothyronine. Although fewer dif-
ferences were recorded during the
postseason period, a main effect (P
<.10) of hunting was seen in
MCHC and mean corpuscular
volume (MCV), and a significant
(P<.10) main effect of diet was
measured for serum albumin and
MCV. Significant (P<.10) inter-
actions between diet and hunting
during the postseason were ob-
served for red blood cells, serum
osmolality, and AST levels.
No significant differences were
seen in fecal stool scores despite the
tendency for stools to be slightly
softer for dogs fed Diet B compared
with those fed Diet A. Most meas-
ures of skin and coat health were
not different, with the exception of
the postseason period in which
dogs fed Diet A werejudged to
havesignificantly shinier and softer
coats compared with those fed Diet
B (P<.05; data not shown).
■DISCUSSION
Assessment of performance in
working dogs is by nature context
specific. The evaluative criteria
that are selected may reflect a dog’s
success rate in the chosen event,
relative level of fitness, or metabolic response
to training and exercise. Laboratory studies
have measured canine fitness in terms of run-
ning speed or time to exhaustion on a tread-
mill, while field studies of sled dogs have used
racing success, biochemical parameters, or sus-
ceptibility to injury as indicators of endurance
Veterinary Therapeutics •Vol. 2, No. 1, Winter 2001
Figure 5. Hunting performance (finds/hour) of English pointers fed two
commercial diets during the quail-hunting season.
*diet effect, P<.05.
Figure 4. Total finds per hunting period of English pointers fed two com-
mercial diets during the quail-hunting season.
*diet effect, P<.05.
**
Total Finds
11/20–12/4 12/5–12/18 1/1–1/15 1/16–1/29 1/30–2/12 2/13–2/26 Overall
Mean
11/20–12/4 12/5–12/18 1/1–1/15 1/16–1/29 1/30–2/12 2/13–2/26 Overall
Mean
****
performance.2,3,10–12 Studies of greyhound rac-
ers typically assess running speed, heat toler-
ance, or blood biochemistry values as a meas-
ure of performance.4,5 In the study reported
here, working ability was measured using both
apractical response criterion (hunting per-
formance) as well as overall biochemical re-
sponses (complete blood chemistry and blood
count data). In terms of the number of points
or birds found during a hunting session, dogs
fed Diet A performed better than did those fed
Diet B. The criteria of number of finds and
time hunting provide a rough, yet practical
measure of each dog’s hunting performance.
Although such assessments are not easily stan-
dardized in a field setting, the two handlers
were blinded to the dietary treatments. This
control allowed comparisons to be made prin-
cipally on each dog’s hunting success during
the season when the only different manage-
ment procedure for each group was the diet
that was fed.
In the study reported here, food intake dur-
ing the hunting season did not change signifi-
cantly in either group of dogs, but dogs fed
Diet A maintained BW and body condition
while those fed Diet B lost weight and condi-
tion. This difference cannot be explained by
increased work frequency in dogs fed Diet B
because there were no differences between
groups in the total time selected to hunt or to-
tal number of hours hunted during the season.
Several dietary factors may have influenced
the hunting ability and body condition of the
dogs in this study. English pointers are highly
activeand do not typically carryadditional
body fat. Furthermore, these dogs typically
lose a considerable amount of condition as the
hunting season progresses. Weight loss, even
when moderate, always comprises both fat and
G. M. Davenport, R. L. Kelley, E. K. Altom, and A. J. Lepine
17
Figure 6. Hunting performance (finds/hour) of English pointers during periods of mild to severeheat stress.
Nov 24 Nov 25 Jan 2 Jan 3 Jan 4 Jan 10 Jan 11 Jan 12 Jan 16 Feb 18 Feb 23 Feb 24 Feb 25 Feb 26
Temperature–Humidity Index (mild = 23.5–26; high = 26–29; severe >29)
Temperature–Humidity Index
Day
Veterinary Therapeutics •Vol. 2, No. 1, Winter 2001
18
TABLE 3. Effect of Diet and Exercise (40-minute simulated hunt) on Selected Blood
Values in Hunting Dogs Fed Two Commercial Diets During Preseason Hunting
Diet A Diet B
Before Hunt After Hunt Before Hunt After Hunt Reference
Variable Mean ± SD Mean ± SD Mean ± SD Mean ± SD Range*
Triglyceride (mg/dL)†27.1 ± 5.5 38.0 ± 8.1 23.5 ± 5.5 39.5 ± 11.3 29–291
Total protein (g/dL)§6.0 ± 0.3 6.3 ± .03 5.9 ± 0.3 6.1 ± 0.4 5.0–7.4
Albumin (g/dL) 3.4 ± 0.2 3.5 ± 0.3 3.3 ± 0.2 3.4 ± 0.2 2.7–4.4
Hematocrit (%)†47.5 ± 5.2 50.6 ± 5.3 45.9 ± 2.6 51.2 ± 3.3 36–60
Hemoglobin (g/dL)§15.2 ± 1.8 16.0 ± 1.6 14.9 ± 1.0 16.2 ± 1.5 12.1–20.3
Red blood cells (×106/µL)§6.3 ± 0.8 6.6 ± 0.8 6.2 ± 0.4 6.8 ± 0.5 4.8–9.3
MCHC (%)§32.0 ± 0.6 31.7 ± 0.3 32.4 ± 0.5 31.6 ± 1.5 30–38
MCV (fL)‡75.8 ± 3.5 77.3 ± 2.8 73.8 ± 2.3 75.2 ± 3.1 58–79
BUN (mg/dL)†17.2 ± 5.9 20.5 ± 3.9 13.2 ± 2.7 18.9 ± 4.1 6–25
Creatinine (mg/dL)§1.2 ± 0.2 1.3 ± 0.2 1.2 ± 0.1 1.3 ± 0.2 0.5–1.6
BUN:Creatinine§13.8 ± 3.6 15.3 ± 3.0 11.4 ± 2.1 14.3 ± 2.6 4–27
AST (U/L)†37.8 ± 14.2 47.9 ± 12.3 32.0 ± 8.7 43.9 ± 10.0 15–66
GGT (U/L)§8.4 ± 1.3 5.3 ± 2.3 6.6 ± 2.6 5.3 ± 2.3 1–12
T4 (µg/dL)†,‡ 1.8 ± 0.9 2.3 ± 0.6 1.2 ± 0.6 1.8 ± 0.5 1.0–4.0
T3 (ng/dL)§88.8 ± 20.2 92.0 ± 27.4 72.1 ± 16.8 93.4 ± 26.5 45–150
Osmolality (mOsm/L)†296.2 ± 2.5 299.4 ± 3.8 292.3 ± 2.8 298.8 ± 3.7 277–311
White blood cells‡7.5 ± 2.1 8.5 ± 1.7 5.9 ± 1.0 6.4 ± 1.5 4.0–15.5
Phosphorus (mg/dL)†4.1 ± 1.2 3.4 ± 0.8 4.3 ± 0.6 3.1 ± 1.0 2.5–6.0
Chloride (mg/dL)†115.1 ± 2.8 112.4 ± 3.3 115.3 ± 3.4 112.5 ± 3.2 102–120
Sodium (mEq/L)§149.1 ± 1.1 149.9 ± 2.0 147.8 ± 1.6 150.2 ± 1.6 139–154
Calcium (mg/dL)§9.6 ± 0.5 9.3 ± 0.4 9.5 ± 0.4 9.2 ± 0.4 8.9–11.4
Fibrinogen (mg/dL)§266.7 ± 102.1 204.8 ± 49.3 206.7 ± 36.4 174.2 ± 46.4 150–400
*Veterinarydiagnostic analyses conducted by Antec Diagnostics (Farmingdale, NY 11735) using accepted commercial
procedures.
†Significant exercise effect (P< .10).
‡Significant diet effect (P< .10).
§Significant diet ×exercise interaction (P< .10).
AST = aspartate aminotransferase; BUN = blood urea nitrogen; GGT = γ-glutamyl transferase; MCHC = mean cor-
puscular hemoglobin concentration; MCV = mean corpuscular volume; SD = standard deviation; T3 = triiodothyronine;
T4 = thyroxine.
lean body tissue.1,13,14 Aloss of lean tissue in
dogs that were not overweight would be ex-
pected to negatively impact body condition
and possibly stamina. Although body compo-
sition data were not collected in this study, pre-
vious research conducted by these investigators
showed that the effect of treadmill exercise on
body composition can be significantly affected
bylevel of dietary fat.15 Both lean body mass
and body fat increased in exercising pointers
fed a diet containing 17% fat, while dogs fed a
diet containing 13% fat lost lean body mass
and body fat in response to treadmill exercise.15
Inthe study reported here, the weight loss of
dogs fed Diet B may be explained bydiffer-
ences in the energy density and caloric distri-
bution of the two foods. The calculated ME
content of Diet A was 4470 kcal/kg compared
with 4210 kcal/kg in Diet B (Table 2). The
slight increase in energy supplied to dogs con-
suming Diet A may havebeen sufficient to
support both weight and body condition de-
spite increased energy needs during periods of
hardwork. The energy density of a food di-
rectly affects the quantity of food that must be
fed to meet an animal’s energy requirement. If
the ME content of a food is too low to support
increased work, the quantity of food that must
be consumed may exceed the physical capacity
of the gastrointestinal tract. In addition, the
consumption of an excessive quantity of food
can lead to an increased rate of passage through
G. M. Davenport, R. L. Kelley, E. K. Altom, and A. J. Lepine
19
TABLE 4. Effect of Diet and Exercise (40-minute simulated hunt) on Selected Blood
Values in Hunting Dogs Fed Two Commercial Diets During Postseason Hunting
Diet A Diet B
Before Hunt After Hunt Before Hunt After Hunt Reference
Variable Mean ± SD Mean ± SD Mean ± SD Mean ± SD Range*
Triglyceride (mg/dL) 38.7 ± 13.6 41.0 ± 7.1 39.0 ± 23.0 45.7 ± 10.8 29–291
Total protein (g/dL) 6.6 ± 0.4 6.6 ± 0.4 6.5 ± 0.4 6.4 ± 0.5 5.0–7.4
Albumin (g/dL)‡3.5 ± 0.2 3.4 ± 0.2 3.3 ± 0.2 3.2 ± 0.2 2.7–4.4
Hematocrit (%) 52.3 ± 4.3 52.0 ± 5.5 49.6 ± 4.8 50.3 ± 3.2 36–60
Hemoglobin (g/dL) 15.8 ± 1.4 16.3 ± 1.8 15.2 ± 1.2 15.9 ± 1.0 12.1–20.3
Red blood cells (×106/µL)§6.3 ± 0.6 6.6 ± 0.7 6.2 ± 0.6 6.7 ± 0.5 4.8–9.3
MCHC (%)†30.1 ± 0.6 31.3 ± 0.6 30.7 ± 1.6 31.6 ± 0.7 30–38
MCV (fL) †,‡ 82.8 ± 3.4 79.3 ± 3.2 79.5 ± 3.2 75.5 ± 3.2 58–79
BUN (mg/dL) 19.5 ± 3.5 20.1 ± 4.8 18.3 ± 4.3 19.3 ± 3.2 6–25
Creatinine (mg/dL) 1.3 ± 0.3 1.2 ± 0.2 1.2 ± 0.3 1.2 ± 0.2 0.5–1.6
BUN:Creatinine 15.5 ± 4.1 17.2 ± 4.2 15.5 ± 2.4 16.8 ± 2.3 4–27
AST (U/L)§32.7 ± 9.2 54.8 ± 32.9 32.5 ± 10.0 42.2 ± 12.3 15–66
GGT (U/L) 5.8 ± 6.8 6.9 ± 8.7 7.0 ± 7.4 4.0 ± 2.7 1–12
T4 (µg/dL) 2.6 ± 0.9 2.8 ± 1.3 2.0 ± 0.7 2.2 ± 0.9 1.0–4.0
T3 (ng/dL) 106.6 ± 25.9 116.7 ± 37.9 101.6 ± 19.6 95.2 ± 19.5 45–150
Osmolality (mOsm/L)§296.1 ± 2.5 302.2 ± 4.9 295.0 ± 3.2 299.0 ± 4.0 277–311
White blood cells 8.1 ± 1.8 8.3 ± 1.8 7.6 ± 1.6 8.0 ± 1.9 4.0–15.5
Phosphorus (mg/dL) 6.0 ± 2.2 3.3 ± 0.9 5.9 ± 1.8 3.1 ± 0.9 2.5–6.0
Chloride (mg/dL) 115.9 ± 5.2 116.2 ± 2.1 115.8 ± 3.2 115.5 ± 4.1 102–120
Calcium (mg/dL) 10.0 ± 0.3 9.6 ± 0.4 9.7 ± 0.4 9.3 ± 0.3 8.9–11.4
Sodium (mEq/L) 148.4 ± 1.5 151.3 ± 2.1 148.2 ± 1.9 149.9 ± 2.4 139–154
Fibrinogen (mg/dL) 221.5 ± 79.3 242.0 ± 97.7 199.2 ± 86.4 170.4 ± 55.5 150–400
*Veterinarydiagnostic analyses conducted by Antech Diagnostics (Farmingdale, NY 11735) using accepted commercial
procedures.
†Significant exercise effect (P< .10).
‡Significant diet effect (P< .10).
§Significant diet ×exercise interaction (P< .10).
AST = aspartate aminotransferase; BUN = blood urea nitrogen; GGT = γ-glutamyl transferase; MCHC = mean cor-
puscular hemoglobin concentration; MCV = mean corpuscular volume; SD = standard deviation; T3 = triiodothyronine;
T4 = thyroxine.
20
the gastrointestinal tract and decreased di-
gestibility, further exacerbating an energy
deficit.
Because fat is a highly available energy
source, an increase in the fat content of the diet
increases both energy density and diet di-
gestibility. The apparent digestibility of the fats
that are included in most pet foods is usually
higher than the digestibility coefficients of the
dietary protein or carbohydrate fractions.16,17
The two foods in this study differed substan-
tially in fat content. Diet A contained 21.4%
fat compared with 17.2% in Diet B (Table 2).
Caloric distribution provides a more accurate
estimate of the proportion of ME supplied by
carbohydrate, protein, and fat. Forty-three per-
cent of the ME of Diet A was provided as fat
compared with 37.6% of ME calories in Diet
B. The higher proportion of fat in Diet A and
greater energy density may explain the differ-
ence in BW in the dogs in this study. The low-
er energy density of Diet B coupled with a low-
er proportion of dietary fat may have possibly
caused this food to be morebulk-limiting as
the energy needs of the dogs gradually in-
creased during the hunting season. If gut fill
were attained before energy needs were met,
Diet B would cause a gradual loss of weight if
it continued to be consumed throughout the
hunting season.
The availability of fat as a metabolic fuel may
also affect performance during strenuous work.
Dogs are efficient aerobic athletes, performing
best when fed a diet that supplies a large pro-
portion of its energy as fat. An early study
showed that when working sled dogs were fed a
high-carbohydrate diet, they performed poorly
and developed signs of injury while racing.2
When the dogs wereswitched to a diet con-
taining increased levels of fat and protein, per-
formance improved and the lameness resolved.
These results were corroborated by recent stud-
ies showing that feeding a high-fat diet to sled
dogs before and during athletic training en-
hanced their ability to mobilize and use fat as a
fuel and improved their aerobic work capaci-
ty.18,19 Controlled studies of dogs running on
treadmills have also shown that endurance per-
formance and olfactory sensitivity are positive-
ly correlated with intake of dietary fat and diet
digestibility.10,15 Because the dogs fed Diet A in
this study were consuming a higher percentage
of calories as fat, Diet A was assumed to have
supplied the extra fuel that was needed for
physical work for these dogs and contributed to
their enhanced performance.
Dietary protein is also an important consid-
eration for canine athletes. Current evidence
indicates that aerobic training imposes an in-
creased need for dietary protein in dogs.3,20 In
all animals, athletic conditioning results in
adaptive physiologic changes that facilitate ef-
ficient delivery of oxygen and nutrients to
working muscles. These changes include in-
creases in blood volume, red blood cell mass,
capillary density, and mitochondrial volume
and occur in the activity and total mass of
metabolic enzymes.21,22 This increased tissue
mass and the need for gluconeogenic amino
acids during exercise necessitate increased pro-
tein intake. Inthe study reported here, protein
contributed 28% of ME calories in Diet A and
25.4% of calories in Diet B. Although both of
these foods exceed the American Association of
Feed Control Officials minimum protein re-
quirement for adult dogs at maintenance, Diet
Bmay have been marginal or limiting in pro-
tein for dogs undergoing physical training.23
The protein content of the diet may also im-
pact the capacity of the blood to oxygenate tis-
sue and transport energy-containing nutrients
needed by working muscles. When fed a diet
containing 28% of ME calories as protein, rac-
ing sled dogs developed anemia and reduced
hematocrit levels compared with those of dogs
fed 32% or more protein.21 More recently, a
Veterinary Therapeutics •Vol. 2, No. 1, Winter 2001
study showed that when fed 35% of calories as
protein, sled dogs maintained a larger plasma
volume and red blood cell mass during training
compared with those of dogs fed diets contain-
ing less than 35% protein.12Dogs fed lower
amounts of protein were also more susceptible
to leg and foot-pad injuries. Although not as
high as the protein content used in studies of
endurance-trained sled dogs, the slightly high-
er proportion of protein in Diet A of the study
reported here compared with that in Diet B
may have been sufficient for these hunting
dogs. Although all values were within the nor-
mal range for healthy dogs, a slight reduction
may become significant during periods of in-
creased physical activity based on increased
needs for oxygen and nutrient transport.
Afinal consideration when selecting the
most appropriate diet for hunting dogs is the
impact of extreme weather conditions. Unlike
sled dogs, which typically run in very cold cli-
mates, hunting dogs may experience high and
low extremes in temperature and humidity. Al-
though the quail-hunting season in Georgia
occurs during the late fall and winter, it can
still be quite warm and humid as evidenced by
the 14 days of mild to severe heat stress during
the season (Figure 6). Despite the increased en-
vironmental temperature and relative humidi-
ty, dogs fed Diet A had more finds per hour
compared with dogs fed Diet B on these days.
Exercise and exposure to high ambient tem-
peratures and humidity all cause an increase in
the amount of energy that must be used to cool
the body.24 Dogs rely primarily on respiratory
evaporation to dissipate excess body heat and
maintain normal body temperature. As a species,
the dog is especially vulnerable to heat stress
and hyperthermia because evaporative cooling
is limited to evaporation from respiration
(panting). Working dogs in humid environ-
ments experience slight increases in energy
needs yet, paradoxically,often exhibit a reduc-
tion in appetite.25Common folklore among
trainers and breeders of hunting dogs is that
feeding a high-fat diet can predispose dogs to
heat stress. However, this belief was not sup-
ported by the performance data in the study
reported here. The increased fat in Diet A did
not negatively affect working ability or stami-
na under the warm and humid conditions.
These results are supported by previous work
showing that feeding a diet containing 13% fat
produced higher rectal temperatures in dogs
after 1 hour of treadmill exercise compared
with the rectal temperature of dogs fed a diet
containing 17% fat.15 These data suggest that
an increased level of dietary fat may benefit the
exercising dog during periods of heat stress by
lowering the corebody temperature.
All of the blood values measured in this
study remained within the normal range for
healthy adult dogs beforeand after the hunting
season. Most of the differences that were ob-
served werein response to hunting and may re-
flect normal metabolic changes associated with
exercise. However, for several parameters, exer-
cise-induced changes weresignificantly influ-
enced bythe diet. These parameters included
serum protein, hemoglobin, red blood cells,
MCHC, GGT,sodium, calcium, and fibrino-
gen during the preseason and red blood cells,
AST, and osmolality during the postseason.
Differing responses to exercise between the two
diet groups may have been caused by dietary
influences on the ability to mobilize energy-
providing nutrients, adapt to increased needs
for oxygen, or maintain acid–base balance and
hydration. Although undue emphasis should
not be placed on changes that remain within
the expected normal range, alterations in blood
chemistry and complete blood cell count pro-
files may provide veterinary practitioners with
additional information regarding the most ap-
propriate diet for working dogs during periods
of increased physical activity.
G. M. Davenport, R. L. Kelley, E. K. Altom, and A. J. Lepine
21
22
■CONCLUSION
Dogs are exceptional aerobic athletes, and
those that are trained for endurance events per-
form best when fed diets that are high in fat
and contain moderately increased protein. In
the study reported here, the food that con-
tained a higher proportion of fat and protein
supported superior hunting performance in
English pointers used to hunt bobwhite quail.
The two diets that were fed are commercially
available and commonly used by breeders,
trainers, and other dog enthusiasts.
The results of this study suggest that the
food selected for conditioned hunting dogs can
directly affect their performance. Factors that
should be considered when selecting a food in-
clude the diet’s fat and protein contents, ingre-
dient quality, energy distribution, and overall
caloric density. Although controlling a field
study to the same degree as a laboratory exper-
iment is impossible, this study provides valu-
able information to trainers, handlers, and cli-
nicians concerned with promoting the best
performance and health in their dogs. Addi-
tional studies by the authors will continue to
elucidate the influence that dietary factors may
have on the working ability, performance, and
health of other types of working dogs.
■ACKNOWLEDGMENT
The authors thank the owners and employ-
ees of the plantation for the use of their hunt-
ing kennel for this study. They also thank
Charles Lingle, DVM; Sonny Odom, DVM;
Karl Dockery, DVM; and Patty Holcomb for
veterinary support and sample collections dur-
ing the study.
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