Objective—To compare secretory responses to prostaglandin (PG) E2 in mucosa obtained from the proximal and distal portions of the colon of dogs.
Sample—Colonic mucosa from cadavers of 18 clinically normal adult dogs.
Procedures—Short-circuit current (ISC) and maximum change in ISC (ΔIsc) in response to administration of 1μM PGE2 were measured across mucosa obtained from the proximal and distal portions of the colon. Responses were evaluated in mucosa (n = 6 dogs) incubated in Ussing chambers with or without 1 mM amiloride or without chloride in the Ringer's bathing solution. Responses were also evaluated in mucosa (n = 9 dogs) incubated with or without pretreatment with 1 μM indomethacin, with or without amiloride in the subsequent bathing solution. Histologic changes in mucosa from 3 dogs were assessed over time.
Results—ISC and ΔISC were significantly reduced when chloride was removed from, but not when amiloride was added to, the bathing solution and were significantly reduced after pretreatment with indomethacin. The ΔISC was significantly greater in mucosa from the distal portion of the colon than in the proximal portion of the colon. Histologic changes after incubation for 3 hours were minimal.
Conclusions and Clinical Relevance—ISC and ΔISC resulted from electrogenic chloride secretion. Chloride secretion was reduced when release of PGs was prevented by indomethacin and was induced by administration of PGE2. Chloride secretion in response to PGE2 was greater in mucosa from the distal portion of the colon than in mucosa from the proximal portion of the colon.
Objective—To determine whether mild restriction of
food intake affects clinicopathologic variables, body
composition, and performance of dogs undertaking
intense sprint exercise.
Animals—9 trained healthy adult Greyhounds.
Procedure—Dogs were offered food free choice
once daily for 9 weeks until body weight and food
intake stabilized. Dogs were then randomly assigned
to be fed either 85% or 100% of this quantity of food
in a crossover study (duration of each diet treatment
period, 9 weeks). Dogs raced a distance of 500 m
twice weekly. Clinicopathologic variables were
assessed before and 5 minutes after racing; food
intake, weight, body composition, body condition
score, and race times were compared at the end of
each diet period.
Results—Compared with values associated with
unrestricted access to food, there were significant
decreases in mean body weight (by 6%) and median
body condition score (from 3.75 to 3.5 on a 9-point
scale) and the mean speed of the dogs was significantly
faster (by 0.7 km/h) when food intake was
restricted. Body composition and most clinicopathologic
variables were unaffected by diet treatment, but
dogs given restricted access to food had slightly
fewer neutrophils, compared with values determined
when food intake was unrestricted.
Conclusions and Clinical Relevance—Results indicate
that the common practice among Greyhound
trainers of mildly restricting food intake of racing dogs
to reduce body weight does improve sprint performance.
A body condition score of approximately 3.5
on a 9-point scale is normal for a trained Greyhound in
racing condition. (Am J Vet Res 2005;66:1065–1070)
Objective—To determine effects of increased dietary
protein and decreased dietary carbohydrate on hematologic
variables, body composition, and racing performance
Animals—8 adult Greyhounds.
Procedure—Dogs were fed a high-protein (HP; 37%
metabolizable-energy [ME] protein, 33% ME fat, 30%
ME carbohydrate) or moderate-protein (MP; 24% ME
protein, 33% ME fat, 43% ME carbohydrate) extruded
diet for 11 weeks. Dogs subsequently were fed
the other diet for 11 weeks (crossover design). Dogs
raced a distance of 500 m twice weekly. Rectal temperature,
hematologic variables before and after racing,
plasma volume, total body water, body weight,
average weekly food intake, and race times were
measured at the end of each diet period.
Results—When dogs were fed the MP diet, compared
with the HP diet, values (mean ± SD) differed
significantly for race time (32.43 ± 0.48 vs 32.61 ±
0.50 seconds), body weight (32.8 ± 2.5 vs 32.2 ± 2.9
kg), Hct before (56 ± 4 vs 54 ± 6%) and after (67 ± 3
vs 64 ± 8%) racing, and glucose (131 ± 16 vs 151 ±
27 mg/dl) and triglyceride (128 ± 17 vs 104 ± 28
mg/dl) concentrations after racing.
Conclusions and Clinical Relevance—Greyhounds
were 0.18 seconds slower (equivalent to 0.08 m/s or
2.6 m) over a distance of 500 m when fed a diet with
increased protein and decreased carbohydrate.
Improved performance attributed to feeding meat to
racing Greyhounds apparently is not attributable to
increased dietary protein and decreased dietary carbohydrate.
(Am J Vet Res 2001;62:440–447)