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  • Author or Editor: Richard A. Swenson x
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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

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

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

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 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

Objectives—To determine effects of dietary antioxidant supplementation on plasma concentrations of antioxidants, exercise-induced oxidative damage, and resistance to oxidative damage during exercise in Alaskan sled dogs.

Animals—62 Alaskan sled dogs.

Procedure—Dogs were matched for age, sex, and ability and assigned to 1 of 3 groups: sedentary and nonsupplemented (control [C]; n = 21), exercised and supplemented (S; 22), and exercised and nonsupplemented (N; 19). Dogs in group S were given 400 units of α- tocopherol acetate, 3 mg of β-carotene, and 20 mg of lutein orally per day for 1 month, then dogs in groups S and N completed 3 days of exercise. Blood samples were collected before and after 1 and 3 days of exercise and after 3 days of rest. Plasma antioxidant concentrations were determined, and oxidative damage to DNA (plasma 7,8 dihydro-8-oxo-2'deoxyguanosine [8-oxodG] concentration) and membrane lipids (plasma hydroperoxide concentration) and resistance of plasma lipoproteins to oxidation were assessed.

Results—Supplementation increased plasma concentrations of α-tocopherol, β-carotene, and lutein. Plasma concentration of α-tocopherol increased and concentration of lutein decreased in group S with exercise. Concentration of 8-oxodG decreased in group S but increased in group N during and after exercise. Lag time of in vitro oxidation of lipoprotein particles increased with exercise in group S only.

Conclusions and Clinical Relevance—Dietary supplementation with antioxidants resulted in increased plasma concentrations of antioxidants. Moreover, supplementation decreased DNA oxidation and increased resistance of lipoprotein particles to in vitro oxidation. Antioxidant supplementation of sled dogs may attenuate exercise-induced oxidative damage. (Am J Vet Res 2000;61:886–891)

Full access
in American Journal of Veterinary Research

Summary

Feline leukemia virus status and antibody titer to feline oncornavirus-associated cell membrane antigen (focma) were determined on plasma from 183 outpatient cats and 61 cats from 2 closed, FeLV-positive, multiple-cat households. Cats with focma antibody titer had a significantly (P < 0.02) higher prevalence of history of disease than did cats without focma antibody. Diseases included upper respiratory tract infections, abscesses, ear infections, lower urinary tract infections, gastrointestinal disease, pneumonia, uterine infection, lymphadenopathy, fever of unknown origin, and bacterial infections. The focma antibody titer was determined by use of an indirect fluorescent antibody test; titer ≥ 1:16 was considered to be positive results. Lower mean focma antibody titer was observed in young cats with history of disease (P < 0.05) than in young cats without history of disease or in older cats with or without history of disease. Prevalence of focma antibody titer was identical (38%) in young and adult cats, indicating cats likely were exposed to FeLV as kittens because a higher prevalence of focma antibody titer in older cats would otherwise be expected.

Free access
in Journal of the American Veterinary Medical Association