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  • Author or Editor: Gregory A. Reinhart x
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Abstract

Objective—To compare fermentation characteristics of fructooligosaccharides (FOS) and other fiber substrates that are commonly found in canine diets.

Sample Population—Fecal samples from 3 adult dogs.

Procedure—The ability of fiber substrates to be used in microbial fermentation reactions was assessed by use of an in vitro fermentation system. Dogs were fed a commercially available food, and feces were collected for use as the microbial inoculum. Substrates used were beet pulp, cellulose, soy fiber, mannanoligosaccharides (MOS), FOS, and 4 inulin products (inulin 1, 2, 3, and 4). Each substrate was incubated anaerobically with fecal inoculum and growth media for 6, 12, and 24 hours, and production of short-chain fatty acids (SCFA) was measured.

Results—Total production of SCFA was higher for fermentation of the 4 inulin products and FOS, whereas fermentation of beet pulp, MOS, and soy fiber resulted in moderate concentrations of SCFA. Fermentation of cellulose produced the lowest concentrations of total SCFA without detection of butyrate or lactate. Butyrate production was greatest for fermentation of the 4 inulin products and FOS. Total lactate production was greatest for FOS and inulin 4. As expected, production of SCFA increased for all substrates as fermentation time increased.

Conclusion and Clinical Relevance—Canine fecal microflora ferment FOS-containing substrates in a similar manner, with little fermentation of cellulosebased carbohydrates. Furthermore, results of an in vitro fermentation system indicate that fiber type affects the metabolic activity of microorganisms, thus influencing the amount and nature of the end products of fermentation. (Am J Vet Res 2001;62: 609–615)

Full access
in American Journal of Veterinary Research

Abstract

Objective

To determine effects of protein intake on blood variables, plasma volume, and maximal oxygen uptake (Vo2max) in sled dogs undergoing rigorous training.

Animals

32 Alaskan sled dogs, between 2 and 6 years old.

Procedure

Dogs were assigned to 1 of 4 groups on the basis of age, sex, and ability. Isocaloric diets containing 18% (diet A), 23% (diet B), 29% (diet C), or 35% (diet D) of energy as protein were assigned randomly to each group and fed 1 month before and during a 12-week training period. Maximal oxygen uptake was measured at 0 (before training) and 12 weeks. Body weight, protein and energy intake, plasma volume, PCV, hemoglobin concentration, and serum biochemical variables were measured at 0, 8, and 12 weeks.

Results

Serum biochemical variables, PCV, and hemoglobin concentration remained within reference ranges for all dogs. Dogs fed diet A had a decrease in Vo2max and a greater rate of soft tissue injury throughout training, compared with dogs fed the other diets. At 12 weeks, dogs fed diets C and D had greater serum sodium concentration and hemoglobin concentration than did dogs fed diet A. Dogs fed diet D also had more plasma volume at 12 weeks than did dogs of any other group.

Conclusions and Clinical Relevance

Consumption of a diet with 18% dietary protein on an energy basis (3.0 g of protein/kg of body weight) is insufficient to meet the metabolic requirements of sled dogs in training. For intense interval work, a diet with 35% dietary protein as energy (6.0 g of protein/kg) may provide a performance advantage by promoting an increase in plasma volume. (Am J Vet Res 1999;60: 789–795)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether repetitive endurance exercise in sled dogs was associated with substantial lipid peroxidation, decreases in antioxidant capacity of the serum, and skeletal muscle damage.

Animals—24 lightly trained sled dogs.

Procedure—16 dogs completed a 58-km run on each of 3 consecutive days; the other 8 dogs (control) did not exercise during the study. Blood samples were collected before the first exercise run and after the first and third exercise runs. Plasma isoprostane and serum vitamin E concentrations, total antioxidant status of plasma, and serum creatine kinase activity were measured.

Results—Plasma isoprostane concentrations in dogs in the exercise group were significantly increased after the first exercise run and further significantly increased after the third exercise run. Serum vitamin E concentration was significantly decreased after the first exercise run in dogs in the exercise group, and this change persisted after the third exercise run. There was a significant linear relationship between plasma isoprostane concentration and the logarithm of serum creatine kinase activity (adjusted r 2 = 0.84).

Conclusions and Clinical Relevance—Results demonstrate that repetitive endurance exercise in dogs is associated with lipid peroxidation and a reduction in plasma antioxidant concentrations. We interpret these results as indicating that the antioxidant mechanisms of minimally trained dogs may, in some instances, be inadequate to meet the antioxidant requirements of repetitive endurance exercise. (Am J Vet Res 2000;61:512–517)

Full access
in American Journal of Veterinary Research

SUMMARY

Objective

To measure energy expenditures of Alaskan sled dogs at rest and during racing under frigid conditions, using the doubly labeled water (DLW) technique.

Animals

18 fit Alaskan sled dogs.

Procedure

Energy expenditure was measured in 9 dogs during a 490-km sled dog race by use of the DLW technique, whereby dogs were administered water enriched with nonradioactive isotopes of hydrogen and oxygen. Energy intake was determined by dietary analysis. Changes in background abundance of the isotopes 2H and 18O were monitored in 5 dogs that did not receive isotope-enriched water.

Results

Dogs completed the 490-km race at an average speed of 7 km/h at ambient temperature of −35 to −10 C. Total energy expenditure, measured by the DLW technique, was 47,100 ± 5,900 kJ/d (4,400 ± 400 kJ·kg-0.75/d), and metabolizable energy intake was 44,600 kJ/d (4,100 kJ·kg-0.75/d) during the 70-hour race.

Conclusions

The sustained metabolic rate for these sled dogs during racing was extraordinarily high for a large mammal. This study validated use of the DLW technique in dogs with exceptionally high energy expenditure associated with prolonged exercise in the cold. (Am J Vet Res 1997;58:1457–1462)

Free access
in American Journal of Veterinary Research

Objective—

To examine the effect of participation in a long-distance race on serum electrolyte concentrations, estimated exchangeable cation content, and acid-base status of Alaskan sled dogs.

Design—

Prospective study.

Animals—

9 male and 5 female, sexually intact, physically fit Alaskan sled dogs between 18 and 48 months old.

Procedure—

Body weight was recorded, and blood samples were collected from dogs before, during, and after a 300-mile race.

Results—

Serum sodium and potassium concentrations decreased during the race, as did serum total protein, albumin, and globulin concentrations and PCV. Effects on acid-base status were minimal. Body weight and estimated total exchangeable cation content in dogs also decreased significantly during the race.

Clinical Implications—

Prolonged running is associated with decreases in serum cation concentration and estimated total exchangeable cation content in dogs, as in human beings and horses. However, the mechanism of the decrease in serum cation concentration likely differs among species. Clinical abnormalities associated with cation depletion were not observed in the dogs in this study. (J Am Vet Med Assoc 1997;210: 1615–1618)

Free access
in Journal of the American Veterinary Medical Association

Objective—

To measure and compare blood values in sled dogs before and after long-distance racing.

Design—

Prospective study.

Animals—

17 adult sled dogs in the 1991 Iditarod Trail Sled Dog Race and 21 in a simulated sled dog race.

Procedure—

Blood samples were obtained from 17 dogs 7 days before they began and after they finished (finisher group) or were eliminated from (nonfinisher group) the Iditarod Trail Sled Dog Race. Blood samples were also obtained from 21 dogs before and after a simulated sled dog race.

Results—

In finisher-group dogs, BUN and uric acid (UA) concentrations were increased after racing; nonfinisher-group dogs had significantly lower postrace BUN and UA concentrations. Significant increases in creatine kinase (CK) and aspartate transferase (AST) activities were detected in all dogs after racing, and postrace values were higher in nonfinisher-group dogs, compared with finisher-group dogs. Mean alkaline phosphate activities were significantly increased after racing in nonfinisher-group dogs only. In dogs that ran the simulated race, postrace values for serum albumin, total protein, calcium, and potassium concentrations, as well as Hct, hemoglobin concentration, and RBC count, were significantly lower than prerace values. Postrace values for alkaline phosphate, alanine transaminase, AST, lactate dehydrogenase, CK, BUN, and UA were significantly higher than prerace values.

Clinical Implications—

High CK activities are indicative of severe muscle degeneration and, in sled dogs, may represent a degree of muscle breakdown beyond which a dog cannot continue to work. Markedly high CK, and possibly AST, serum activities may be indicators of performance failure in sled dogs competing in long-distance races. (J Am Vet Med Assoc 1997; 211:175–179)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To evaluate the protective effects of dietary n-3 fatty acid supplementation versus treatment with a thromboxane synthetase inhibitor (TXSI) in dogs given high-dose gentamicin.

Design

Clinicopathologic and renal histopathologic changes induced by gentamicin (10 mg/kg of body weight, IM, q 8 h, for 8 days) were compared in dogs fed an n-3 fatty acid-supplemented diet containing a fatty acid ratio of 5.7:1 (n-6:n-3), dogs treated with CGS 12970 (a specific TXSI given at 30 mg/kg, PO, q 8 h, beginning 2 days prior to gentamicin administration), and control dogs. The TXSI-treated and control dogs were fed a diet with a fatty acid ratio of 51.5:1 (n-6:n-3). Both diets were fed beginning 42 days prior to and during the 8-day course of gentamicin administration.

Animals

Eighteen 6-month-old male Beagles, 6 in each group.

Results

After 8 days of gentamicin administration, differences existed among groups. Compared with n-3-supplemented and control dogs, TXSI-treated dogs had higher creatinine clearance. Both TXSI-treated and n-3-supplemented dogs had higher urinary prostaglandin E2 and E3 (PGE2/3) and 6-keto prostaglandin F (PGF) excretion, compared with control dogs. Urinary thromboxane B2 (TXB2) excretion was higher in n-3-supplemented and control dogs, compared with TXSI-treated dogs. Urine PGE2/3-to-TXB2 and PGF-to-TXB2 ratios were increased in TXSI-treated dogs, compared with n-3-supplemented and control dogs, and these ratios were increased in n-3-supplemented dogs, compared with control dogs. In addition, TXSI-treated and n-3-supplemented dogs had lower urinary protein excretion, compared with control dogs. Proximal tubular necrosis was less severe in TXSI-treated dogs, compared with control dogs.

Conclusion

Treatment with CGS 12970 prior to and during gentamicin administration prevented increases in urinary TXB2 excretion and reduced nephrotoxicosis.

Clinical Relevance

Increased renal production/excretion of thromboxane is important in the pathogenesis of gentamicin-induced nephrotoxicosis. (Am J Vet Res 1996;57:948–956)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether dietary antioxidants would attenuate exercise-induced increases in plasma creatine kinase (CK) activity in sled dogs.

Animals—41 trained adult sled dogs.

Procedure—Dogs, randomly assigned to 2 groups, received the same base diet throughout the study. After 8 weeks on that diet, 1 group (21 dogs) received a daily supplement containing vitamins E (457 U) and C (706 mg) and β-carotene (5.1 mg), and a control group (20 dogs) received a supplement containing minimal amounts of antioxidants. After 3 weeks, both groups performed identical endurance exercise on each of 3 days. Blood samples were collected before and 3 weeks after addition of supplements and after each day of exercise. Plasma was analyzed for vitamins E and C, retinol, uric acid, triglyceride, and cholesterol concentrations, total antioxidant status (TAS), and CK activity.

Results—Feeding supplements containing antioxidants caused a significant increase in vitamin E concentration but did not change retinol or vitamin C concentrations or TAS. Exercise caused significantly higher CK activity, but did not cause a significant difference in CK activity between groups. Exercise was associated with significantly lower vitamin E, retinol, and cholesterol concentrations and TAS but significantly higher vitamin C, triglyceride, and uric acid concentrations in both groups.

Conclusions and Clinical Relevance—Use of supplements containing the doses of antioxidants used here failed to attenuate exercise-induced increases in CK activity. Muscle damage in sled dogs, as measured by plasma CK activity, may be caused by a mechanism other than oxidant stress. (Am J Vet Res 2000;61:1438–1445)

Full access
in American Journal of Veterinary Research

SUMMARY

Objectives

To ascertain the effects of dietary omega-3 (n-3) fatty acids on biochemical and histopathologic components of the inflammatory stage of wound healing.

Animals

30 purpose-bred Beagles.

Procedure

Dogs were allotted to 5 groups of 6. Each group was fed a unique dietary fatty acid ratio of omega-6 to n-3—diet A, 5.3:1; diet B, 10.4:1; diet C, 24.1:1; diet D, 51.6:1; and diet E, 95.8:1. Dogs were fed once daily for 12 weeks, then biopsy specimens were taken from 4-day-old wounds of each dog and analyzed by gas chromatography-mass spectrometry for: prostaglandin E2 (PGE2) metabolites, and ratios of omega-6 to n-3 fatty acids, arachidonic acid (AA) to eicosapentaenoic acid (EPA), adrenic acid to docosahexaenoic acid, and PGE2 to prostaglandin E3 (PGE3) metabolites.

Results

Qualitative analysis was carried out on AA, EPA, adrenic acid, docosahexaenoic acid, and the major metabolite from the PGE2 and PGE3 pathway. These molecules were further quantified with respect to diet to determine significant differences. By analysis of the AA-to-EPA ratio, diet A was different from diets D and E and diets B and C were different from diet E (P < 0.05). By analysis of the PGE2-to-PGE3 metabolite ratio, diet A was different from diet E (P < 0.05). Though biochemical analysis indicated dietary dependence, histopathologic data indicated no significant difference with respect to diet groups.

Conclusion

The biochemical component of the inflammatory stage of wound healing can be manipulated by diet.

Clinical Relevance

Omega-3 fatty acid-enriched diets can be used to control inflammation associated with dermatologic conditions. (Am J Vet Res 1998;59:859–863)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To study the musculoskeletal development of Great Dane puppies fed various dietary concentrations of calcium (Ca) and phosphorus (P) in fixed ratio by use of dual energy x-ray absorptiometry (DEXA), determination of serum insulin-like growth factor I and parathyroid hormone concentrations, radiography, and blood chemistry analysis results.

Animals—32 purebred Great Dane puppies from 4 litters.

Procedure—At weaning, puppies were assigned randomly to 1 of 3 diets. Blood was collected for biochemical analyses and hormone assays, and radiography and DEXA were performed through 18 months of age. Changes in body weight, bone mineral content, fat tissue weight, lean mass, result of serum biochemical analyses, hormonal concentrations, and radius lengths were analyzed through 18 months of age.

Results—Bone mineral content of puppies correlated positively with Ca and P content of the diets fed. Significant differences between groups in bone mineral content, lean mass, and body fat were apparent early. The disparity among groups increased until 6 months of age and then declined until body composition was no longer different at 12 months of age. Accretion rates for skeletal mineral content, fat, and lean tissue differed from each other and by diet group.

Conclusions and Clinical Relevance—Ca and P concentrations in the diet of young Great Dane puppies are rapidly reflected in the bone mineral content of the puppies until 5 to 6 months of age, after which hormonal regulation adjusts absorption and excretion of these minerals. Appropriate Ca and P concentrations in diets are important in young puppies < 6 months of age. (Am J Vet Res 2002;63:1036–1047)

Full access
in American Journal of Veterinary Research