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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)

Full access
in American Journal of Veterinary Research

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)

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in American Journal of Veterinary Research

Abstract

Objectives—To determine maintenance energy requirements and effect of diet on performance of racing Greyhounds.

Animals—7 adult racing Greyhounds.

Procedure—Dogs were fed a higher fat and protein (HFP) or a lower fat and protein (LFP) diet for 8 weeks in a crossover design. Dogs were exercised for 15 minutes twice daily in a paddock and raced 500 m twice weekly. Blood gas, hematologic, and serum biochemical analyses were performed before and after racing, and race times were compared at the end of each diet period.

Results—Mean race time was significantly shorter (32.81± 0.65 seconds vs 33.05 ± 0.71 seconds), and mean racing speed over 500 m was significantly faster (15.25 ± 0.30 vs 15.13 ± 0.30 m·s–1) when dogs were fed the HFP diet than when they were fed the LFP diet. Diet had little or no effect on results of blood gas, hematologic, and serum biochemical analyses, except that Hct was 4% greater before and after racing when the HFP diet was fed than when the LFP diet was fed. Mean SD metabolizable energy intake from weeks 1 through 16 was 155 ± 9 kcal·kg–0.75·d–1.

Conclusions and Clinical Relevance—Racing Greyhounds ran faster when fed a diet containing higher fat and protein and lower carbohydrate contents. Their maintenance metabolizable energy requirement was slightly higher than that of moderately active dogs. (Am J Vet Res 2000;61:1566–1573)

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in American Journal of Veterinary Research

Abstract

Objective

To determine whether healthy dogs given high doses of methylprednisolone sodium succinate (MPSS) develop gastrointestinal tract ulcers and hemorrhage.

Animals

19 healthy male hound-type dogs.

Procedure

Dogs were assigned randomly to intravenously receive high doses of MPSS (30 mg/kg of body weight, initially, then 15 mg/kg 2 and 6 hours later, and, subsequently, every 6 hours for a total of 48 hours; n = 10) or an equal volume of saline (0.9% NaCl) solution (9). Gastroduodenoscopy was performed before and after treatment. Endoscopic evidence of gross hemorrhage in the cardia, fundus, antrum, and duodenum of each dog was graded from none (0) to severe (3), and a total stomach score was calculated as the sum of the regional gastric scores. Number of ulcers were recorded. The pH of gastric fluid and evidence of occult gastric and fecal blood were measured. Food retention was recorded.

Results

Gastric hemorrhage was evident in all dogs after MPSS administration and was severe in 9 of 10 dogs but not visible in any dog after saline treatment. Occult gastric blood was detected more commonly (9/10 vs 2/9), median gastric acidity was greater (pH 1 vs pH 3), and food was retained more commonly (7/10 vs 1/9) in the stomach of MPSS-treated dogs.

Conclusions and Clinical Relevance

High doses of MPSS cause gastric hemorrhage in dogs. All dogs treated with high doses of MPSS should be treated with mucosal protectants or antacids to prevent gastric hemorrhage. (Am J Vet Res 1999;60:977–981)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine whether administration of misoprostol prevents gastric hemorrhage in healthy dogs treated with high doses of methylprednisolone sodium succinate (MPSS).

Animals

18 healthy hound-type dogs of both sexes.

Procedure

All dogs were given high doses of MPSS (30 mg/kg of body weight, initially, then 15 mg/kg 2 and 6 hours later, and, subsequently, q 6 h for a total of 48 hours) IV. Dogs were assigned randomly to receive concurrent treatment with misoprostol (4 to 6 μg/kg, PO, q 8 h; n = 9) or an empty gelatin capsule (9). Gastroduodenoscopy was performed before and after treatment. Hemorrhage was graded from none (0) to severe (3) for each cardia, fundus, antrum, and duodenum. A total stomach score was calculated as the sum of the regional stomach scores. Food retention was recorded, and pH of gastric fluid was determined. Gastric and fecal occult blood was measured.

Results

Gastric hemorrhage was evident in all dogs after MPSS administration, and its severity was similar in both groups. Median total stomach score was 6 for misoprostol-treated dogs and 5.5 for dogs given the gelatin capsule. Difference in gastric acidity, frequency of food retention, and incidence of occult blood in gastric fluid and feces was not apparent between the 2 groups.

Conclusions and Clinical Relevance

Administration of misoprostol (4 to 6 μg/kg, PO, q 8 h) does not prevent gastric hemorrhage caused by high doses of MPSS. Alternative prophylactic treatment should be considered. (Am J Vet Res 1999;60:982–985)

Free access
in American Journal of Veterinary Research