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- Author or Editor: Richard C. Hill x
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Abstract
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.
Abstract
Objective—To compare guaranteed and measured concentrations of nutrients in commercial pet foods.
Design—Cross-sectional study.
Sample Population—Annual inspection reports of pet food analyses from 5 states.
Procedures—Guaranteed and measured concentrations of crude protein (CP), crude fat (CF), crude fiber (CFb), moisture, and ash in pet foods were compared. The concentration difference for each nutrient was compared among types of food, target species, target life stages, manufacturers, and laboratories.
Results—The guaranteed and measured concentrations of nutrients were significantly different. For all foods, mean concentration differences were as follows: CP, 1.5%; CF, 1.0%; CFb, −0.7%; moisture, −4.0%; and ash, −0.5%. Crude protein difference for treats was significantly larger than differences for dry and canned foods. Crude fat difference for dry foods was significantly less than differences for canned foods and treats. Crude fiber and moisture differences for canned foods were significantly less than the corresponding differences for dry foods and treats. Only CFb differences differed among target species, life stages, manufacturers, or laboratories.
Conclusions and Clinical Relevance—Addition of 1.5% and 1% to the guaranteed minimums for CP and CF, respectively; subtraction of 0.7%, 4%, and 0.5% from the guaranteed maximums for CFb, moisture, and ash, respectively; and addition of 0.23 kcal/g to the asfed metabolizable energy value calculated by use of modified Atwater factors from guaranteed analyses provides a more accurate estimate of the nutrient and metabolizable energy content of commercial pet foods. Nevertheless, the actual composition of a food should be determined whenever possible.
Abstract
Objective—To measure volatile fatty acid (VFA) concentrations and pH in the gastrointestinal tracts of healthy adult cats fed a commercial dry cat food.
Animals—14 cats.
Procedure—The gastrointestinal tracts were excised immediately after euthanasia and divided into 6 sections (stomach, duodenum, jejunum, ileum, proximal portion of the colon, and distal portion of the colon). Luminal contents were collected from each segment, pH was measured, and contents were centrifuged. The supernatant was analyzed for acetate, proprionate, butyrate, isobutyrate, valerate, and isovalerate concentrations by use of gas chromatography.
Results—Mean total VFA concentrations were lowest in the stomach (20 mmol/L); increased through the duodenum, jejunum, and ileum (30, 29, and 41 mmol/L, respectively); and were greatest in the proximal and distal portions of the colon (109 and 131 mmol/L, respectively). Estimated mean total VFA amounts were low (< 600 μmol) throughout all segments of the gastrointestinal tract; pH values increased from the stomach through the ileum and subsequently decreased in the colon.
Conclusions and Clinical Relevance—Total VFA concentrations in the colon were comparable to values reported for the forestomach of ruminants and large intestines of monogastric animals, whereas values in the small intestine were higher than reported for other species. Total VFA amounts were low, consistent with the short, nonvoluminous gastrointestinal tract of carnivores. Luminal pH varied throughout the gastrointestinal tract in a pattern similar to other monogastric animals. Volatile fatty acids probably contribute minimal metabolic energy in cats but may be important in the maintenance of local mucosal health. (Am J Vet Res 2000;61:359–361)
Abstract
OBJECTIVE
To evaluate the effects of a flotation vest (FV) and water flow rate (WFR) on limb kinematics of dogs swimming against a current.
ANIMALS
7 (1 male and 6 female) healthy adult Siberian Huskies.
PROCEDURES
Dogs were habituated to swim with and without an FV beside an investigator in a continuous-flow pool against WFRs up to 2.9 km/h. During each of 4 experimental sessions in a repeated-measures study, markers were wrapped around the right carpus and tarsus, and a video was recorded while each dog swam with or without an FV for about 2 minutes at each of 7 WFRs between 0 and 2.9 km/h when the WFR was incrementally decreased or increased. Motion tracking software was used to measure stroke excursion and frequency.
RESULTS
Stroke excursion varied more than frequency among all dogs and in response to changes in experimental conditions. The male dog and 1 female dog were unable to complete the study. For the remaining 5 dogs across all experimental conditions, mean tarsus excursion was 30% that of the carpus. Mean total excursion (sum of the excursion-frequency products for the carpus and tarsus) decreased when an FV was worn and increased with WFR by 69% and 19% when WFR was incrementally increased and decreased, respectively.
CONCLUSIONS AND CLINICAL RELEVANCE
In dogs, range of motion during swimming was greater for the carpus than tarsus, when an FV was not worn, and increased more with WFR when WFR was incrementally increased. Those factors should be considered during swimming-based rehabilitation.
Abstract
Objective—To determine whether plasma concentrations of benzodiazepines (BDZ) in dogs following intranasal (IN) administration of diazepam are comparable to concentrations following IV administration.
Animals—6 (4 male, 2 female) healthy adult Greyhounds.
Procedure—Dogs were randomly assigned to 2 groups of 3 dogs in a crossover design. Diazepam (0.5 mg/kg of body weight) was administered intravenously to dogs in group 1 and intranasally to dogs in group 2. Blood was collected from the jugular vein of each dog into tubes containing lithium heparin before and 3, 6, 9, 12, 15, 20, 30, 60, 120, 240, and 480 minutes following diazepam administration. After a 4-day washout period, dogs in group 1 received diazepam intranasally, dogs in group 2 received diazepam intravenously, and blood was again collected. Plasma concentration of BDZ was determined by use of a fluorescence polarization immunoassay.
Results—Mean (± SD) peak plasma concentration of BDZ following IV administration (1316 ± 216 µg/L) was greater than that following IN administration (448 ± 41 µg/L). Time to peak concentration was ≤ 3 minutes following IV administration and 4.5 ± 1.5 minutes following IN administration. Mean bioavailability of BDZ following IN administration was 80 ± 9%.
Conclusions and Clinical Relevance—Diazepam is rapidly and efficiently absorbed following IN administration of the parenteral formulation. Plasma concentrations match or exceed the suggested therapeutic concentration (300 µg/L). Intranasal administration of diazepam may be useful for treatment of seizures in dogs by owners or when intravenous access is not readily available. (Am J Vet Res 2000;61:651–654)
Abstract
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)
Abstract
Objectives—To determine effect of α-tocopherol supplementation on serum vitamin E concentrations in Greyhounds before and after a race.
Animals—8 adult racing Greyhounds.
Procedure—Dogs were given 2 capsules of α-tocopheryl acetate (total, 680 units [0.5 g]) with food that contained ≤ 15 mg of vitamin E/kg each morning for 7 days. Dogs were exercised in a 30 × 30-m grass paddock for 15 minutes twice a day and raced for 500 m twice a week. Blood samples were collected before and 5 minutes after a race, before supplementation was begun, and after 7 days of supplementation. Blood and diet samples were analyzed for tocopherols and α-tocopheryl acetate.
Results—Before supplementation, serum α-tocopherol concentration after racing (mean ± SD, 6.7 ± 2.4 mg/L ) was significantly lower than before racing (12.2 ± 3.1 mg/L). After supplementation, α- tocopherol concentrations were significantly higher overall, although values obtained before (26.6 ± 5.2 mg/L) and after (29.8 ± 3.6 mg/L) racing were not significantly different.
Conclusions and Clinical Relevance—Supplementation with α-tocopheryl acetate increased serum α-tocopherol concentrations and eliminated the decrease in α-tocopherol concentration that was detected after a race, which may decrease oxidation during exercise and improve performance or recovery. (Am J Vet Res 2001;62:1118–1120)
Abstract
Objective—To determine effects of increased dietary protein and decreased dietary carbohydrate on hematologic variables, body composition, and racing performance in Greyhounds.
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)
Abstract
Objectives—To determine the effects of racing and training on serum thyroxine (T4), triiodothyronine (T3), and thyroid stimulating hormone (TSH) concentrations in Greyhounds.
Animals—9 adult racing Greyhounds.
Procedure—Serum thyroid hormone concentrations were measured before and 5 minutes after a race in dogs trained to race 500m twice weekly for 6 months. Resting concentrations were measured again when these dogs had been neutered and had not raced for 3 months. Postrace concentrations were adjusted relative to albumin concentration to allow for effects of hemoconcentration. Thyroid hormone concentrations were then compared with those of clinically normal dogs of non-Greyhound breeds.
Results—When adjusted for hemoconcentration, total T4 concentrations increased significantly after racing and TSH concentrations decreased; however, there was no evidence of a change in free T4 or total or free T3 concentrations. Resting total T4 concentrations increased significantly when dogs had been neutered and were not in training. There was no evidence that training and neutering affected resting TSH, total or free T3, or free T4 concentrations. Resting concentrations of T3, TSH, and autoantibodies against T4, T3, and thyroglobulin were similar to those found in other breeds; however, resting free and total T4 concentrations were lower than those found in other breeds.
Conclusions and Clinical Relevance—Except for total T4, thyroid hormone concentrations in Greyhounds are affected little by sprint racing and training. Greyhounds with low resting total and free T4 concentrations may not be hypothyroid. (Am J Vet Res 2001;62:1969–1972)
