Effects of racing and nontraining on plasma thyroid hormone concentrations in sled dogs

OBJECTIVE: To determine the effects of racing and nontraining on plasma thyroxine (T4), free thyroxine (fT4), thyroid-stimulating hormone (TSH), and thyroglobulin autoantibody (TgAA) concentrations in sled dogs and compare results with reference ranges established for dogs of other breeds. DESIGN: Cross-sectional study. ANIMALS: 122 sled dogs. PROCEDURE: Plasma thyroid hormone concentrations were measured before dogs began and after they finished or were removed from the Iditarod Trail Sled Dog Race in Alaska and approximately 3 months after the race. RESULTS: Concentrations of T4 and fT4 before the race were less than the reference range for nonsled dogs in 26% and 18% of sled dogs, respectively. Immediately after racing, 92% of sled dogs had plasma T4 concentrations less than the reference range. Three months after the race, 25% of sled dogs had plasma T4 concentrations less than the reference range. For T4, fT4, TSH, and TgAA, significant differences were not detected in samples collected before the race versus 3 months later. CONCLUSIONS AND CLINICAL RELEVANCE: Plasma T4, fT4, and TSH concentrations decreased in dogs that complete a long distance sled dog race. Many clinically normal sled dogs have plasma T4 and fT4 values that are lower than the reference range for nonsled dogs. We suggest that the reference ranges for sled dogs are 5.3 to 40.3 nmol/L and 3.0 to 24.0 pmol/L for plasmaT4 and fT4 concentrations, respectively, and 8.0 to 370 mU/L for TSH.     

Evaluation of plasma inflammatory cytokine concentrations in racing sled dogs

In human athletes significant changes in cytokine concentrations secondary to exercise have been observed. This prospective study evaluated the effect of a multi-day stage sled dog race on plasma concentrations of monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-α), interleukin-2 (IL-2), interleukin-6 (IL-6), interleukin-8 (IL-8), and interleukin-10 (IL-10). Samples from 20 dogs were harvested prior to and on days 2 and 8 of an 8-day race. Exercise resulted in significantly decreased TNF-α and IL-8 as well as increases of MCP-1, IL-6, and IL-10 concentrations (P-value between 0.01 and < 0.0001 for all parameters). The proportion of values for IL-2 that were below the detection limit increased from 40% on day 0 to 75% on day 2 and decreased on day 8 to 40% (P = 0.04). Racing sled dogs show cytokine-concentration changes that are different from those in humans.     

Plasma thyroid hormone concentrations in dogs competing in a long-distance sled dog race

Plasma thyroxine (T4), 3,5,3'-triiodothyronine (T3), total protein, and albumin concentrations were measured in 15 dogs both before and after completion, and in an additional 16 dogs before and 24 dogs after completion, of a long-distance sled dog race. The plasma T4 concentration (mean +/- SD) decreased significantly from 18.2 +/- 5.4 nmol/L before to 14.3 +/- 3.5 nmol/L after the race in dogs evaluated at both times and decreased significantly from 21.8 +/- 10.5 nmol/L before to 15.8 +/- 4.9 nmol/L after the race in dogs sampled only before or only after the race. The mean plasma T3 concentrations in dogs measured twice decreased significantly from 1.20 +/- 0.48 nmol/L before to 0.74 +/- 0.42 nmol/L after the race, as well as in dogs measured either before (1.28 +/- 0.36 nmol/L) or after (0.69 +/- 0.28 nmol/L) the race, respectively. Plasma total protein and albumin concentrations decreased significantly after completion of the race. No significant change was noted in 4 control dogs that did not compete in the race and were tested during a similar time period. The plasma concentrations of T4 and T3 were lower than the normal reference range established for this laboratory in 23 and 39%, respectively, of Alaskan sled dogs tested before the race. Plasma thyroid hormone concentrations frequently are below normal in conditioned Alaskan sled dogs and are further reduced after prolonged submaximal exercise.     

Hypogammaglobulinemia in Racing Alaskan Sled Dogs

Background: Serum immunoglobulin dynamics have not been studied in racing sled dogs, despite hypoglobulinemia having been reported during racing events.
Hypothesis/Objectives: Hypoglobulinemia in racing sled dogs is associated with decreases in serum IgA, IgE, IgG, and IgM concentrations during prolonged exercise.
Animals: One hundred and fifty-seven Alaskan sled dogs that successfully completed a 1,000 mile race.
Methods: Serum was obtained from 118 sled dogs within 1 month before the race and within 12 hours after completing the race. Serum also was obtained after 4 months of rest from 51 dogs that successfully completed the race, including 12 previously sampled dogs. Serum total protein ([TP]), albumin, and globulin ([Gl]) were measured, and serum IgA, IgE, IgG, and IgM were quantified by ELISA.
Results: The proportion of dogs with [Gl] ≤ 2.2 g/dL was significantly greater immediately after racing (38 of 118 dogs, 32.2%) than before racing (21 of 118 dogs, 17.8%, P = .005). Four months after racing, [Gl] was ≤ 2.2 g/dL in 23.5% (12 of 51) of dogs. [IgG] was significantly lower before (8.21 ± 4.95 mg/mL) and immediately after (7.97 ± 5.62) racing compared with 4 months after racing (18.88 ± 5.76). Serum [IgM] and [IgE] were higher and [IgA] was lower before racing compared with immediately after racing.
Conclusions and Clinical Importance: Sled dogs participating in long-distance racing have substantial decreases in [IgG] in addition to decreases in [IgM] and [IgE]. The pronounced hypogammaglobulinemia observed in a large proportion of racing sled dogs might predispose them to infectious disease.     

Exercise induced hypercoagulability,increased von Willebrand factor and decreased thyroid hormone concentrations in sled dogs

Background

Sled dogs performing endurance races have been reported to have a high incidence of gastric erosions or ulcerations and an increased risk of gastro intestinal bleeding leading to death in some cases. In addition, these dogs also become hypothyroid during training and exercise. Canine hypothyroidism has been shown to correlate with decreased von Willebrand factor antigen and potentially increased bleeding tendency. Whether increased gastro intestinal bleeding risk is exacerbated due to changes in the hemostatic balance is unknown. The aim of this study was to investigate the hemostatic balance in sled dogs before and after exercise and in addition evaluate any correlation to thyroid status. Twenty sled dogs have been assessed in untrained and trained condition and immediately after exercise. The first sample was collected in the autumn following a resting period, and subsequently the dogs were exposed to increased intensity of training. After four months the peak of physical condition was reached and a 68 km long sled pulling exercise was performed. Samples were collected before and immediately after the exercise. Evaluated parameters were: plasma thromboelastographic (TEG) R, SP, α and MA, activated partial thromboplastin time (aPTT), prothrombin time (PT), fibrinogen, von Willebrand factor (vWf), D-dimer, platelet number, thyroid hormones, hematocrit and C-reactive protein (CRP).

Results

Exercise induced an overall hypercoagulable state characterized by significant decreases of TEG R and SP and an increase of α, increased concentrations of plasma vWf and decreased aPTT. In addition, a proinflammatory status was seen by a significant increase of serum CRP concentrations. Thyroid status was confirmed to be hypothyroid as training and exercise induced significant decrease of thyroxin (T4), free thyroxin (fT4) and thyroxin stimulating hormone (TSH) concentrations. Fibrinogen decreased significantly and PT increased. The training-induced changes showed correlation between T4, fT4 and aPTT and correlation between TSH and fibrinogen. Exercise-induced changes showed correlation between T4 and PT.

Conclusions

Exercise was associated with a hypercoagulable state and an increase of vWf concentration in this group of sled dogs. Decreased thyroid hormone concentrations after training and exercise were confirmed, but were associated with increased and not decreased vWf in this group of sled dogs.     

Assessment of alterations in triglyceride and glycogen concentrations in muscle tissue of Alaskan sled dogs during repetitive prolonged exercise

OBJECTIVE: To assess changes in muscle glycogen (MG) and triglyceride (MT) concentrations in aerobically conditioned sled dogs during prolonged exercise. ANIMALS: 54 Alaskan sled dogs fed a high-fat diet. PROCEDURES: 48 dogs ran 140-km distances on 4 consecutive days (cumulative distance, up to 560 km); 6 dogs remained as nonexercising control animals. Muscle biopsies were performed immediately after running 140, 420, or 560 km (6 dogs each) and subsequently after feeding and 7 hours of rest. Single muscle biopsies were performed during recovery at 28 hours in 7 dogs that completed 560 km and at 50 and 98 hours in 7 and 6 dogs that completed 510 km, respectively. Tissue samples were analyzed for MG and MT concentrations. RESULTS: In control dogs, mean +/- SD MG and MT concentrations were 375 +/- 37 mmol/kg of dry weight (kgDW) and 25.9 +/- 10.3 mmol/kgDW, respectively. Compared with control values, MG concentration was lower after dogs completed 140 and 420 km (137 +/- 36 mmol/kgDW and 203 +/- 30 mmol/kgDW, respectively); MT concentration was lower after dogs completed 140, 420, and 560 km (7.4 +/- 5.4 mmol/kgDW; 9.6 +/- 6.9 mmol/kgDW, and 6.3 +/- 4.9 mmol/kgDW, respectively). Depletion rates during the first run exceeded rates during the final run. Replenishment rates during recovery periods were not different, regardless of distance; only MG concentration at 50 hours was significantly greater than the control value. CONCLUSIONS AND CLINICAL RELEVANCE: Concentration of MG progressively increased in sled dogs undergoing prolonged exercise as a result of attenuated depletion.     

Effect of exercise on the mobilization of retinol and retinyl esters in plasma of sled dogs

Fasting dogs do transport vitamin A (VA) in plasma not only as retinol but predominantly as retinyl esters. Contrary to retinol, nothing is known concerning the effects of athletic performance on plasma retinyl ester concentrations. The aim of this study was therefore to examine whether physical stress because of exercise and modification of the oxidative stress by supplementation of alpha-tocopherol influences the concentrations of retinol and retinyl esters in plasma of sled dogs. The study was carried out on 41 trained adult sled dogs, which were randomly assigned into two groups. One group (19 dogs) was daily substituted with 50 mg dl-alpha-tocopheryl acetate per kilogram body weight and the control group (22 dogs) was maintained on a basal diet during 3 months prior to exercise. The plasma concentrations of retinol, retinyl esters, alpha-tocopherol and triglycerides were measured immediately before, directly after and 24 h after exercise. The supplementation of alpha-tocopheryl acetate had no effect on plasma retinol and retinyl ester concentrations at any measurement time point. However, retinyl ester levels doubled in the non-supplemented group immediately after the race (p < 0.001), whereas in the supplemented group similar high levels were observed not until 24 h post-racing (p < 0.001). The high levels of retinyl esters were paralleled to some extent by an increase in plasma triglyceride concentrations, which were significantly higher 24 h post-racing than immediately before (p < 0.001) and after exercise (p < 0.001) in both groups. The increase in retinyl ester concentrations might be indicative of their mobilization from liver and adipose tissue. Whether plasma retinyl esters can be used as an indicator for the extent of nutrient mobilization during and post-exercise in sled dogs remains to be elucidated.     

Toxicokinetics of mercury in blood compartments and hair of fish-fed sled dogs

Background

Understanding mercury (Hg) distribution in blood and the importance of hair as an excretory pathway is critical for evaluating risk from long term dietary Hg exposure. The major objective of this study was to characterize changes in total Hg concentrations in specific blood compartments and hair over time due to long term piscivory.

Methods

Eight sled dogs (Canis lupus familiaris) were fed either a fish and kibble diet (n = 4), or a fish-free control diet (n = 4) for 12 weeks. Concentrations of Hg were monitored throughout the exposure period, and for 10 weeks post exposure, until Hg concentrations in all blood compartments of one of the exposed dogs dropped below detection limit. Additionally, foreleg hair was sampled during acclimation and weeks 0 and 12.

Results

Hg was detected primarily in whole blood and packed cells, although it was sporadically detected at low concentrations in plasma and serum in two of the fish fed dogs. Dogs ingested an estimated average of 13.4 ± 0.58 μg Hg per kg body weight per day. Hg was detectable in whole blood and packed cells within a week of exposure. Detected concentrations continued to rise until plateauing at approximately 3-6 weeks of exposure at a mean of 9.2 ± 1.97 ng/g (ppb) in whole blood. Hg concentration decreased post exposure following 1st order elimination. The mean half-life (t_1/2) in whole blood for Hg was 7 weeks. Mean Hg in hair for the fish-fed dogs at week 12 was 540 ± 111 ppb and was significantly greater (about 7-fold) than the Hg hair concentration for the control dogs. The hair to blood ratio for Hg in fish-fed dogs was 59.0 ± 7.6:1.

Conclusions

This study found the sled dog model to be an effective method for investigating and characterizing blood Hg distribution (whole blood, serum, plasma, packed cells) and toxicokinetics associated with a piscivorous diet, especially for Hg-exposed fur bearing mammals (such as polar bears). Although hair excretion and hair to blood Hg ratios were not similar to human concentrations and ratios, the sled dog toxicokinetics of Hg in blood, was more similar to that of humans than traditional laboratory animals (such as the rat).     

Effect of transportation and weaning on humoral immune responses of calves

Transportation exposes cattle to stress and results in increased morbidity and mortality. An investigation was made of the effects of transport and another important stressor, weaning, on the immune function of calves by determining Immoral immune responses to keyhole limpet haemocyanin (KLH). In a 2 × 2 factorial designed experiment, suckled calves were either (1) weaned at housing (day 0) and not transported, (2) weaned at housing and transported, (3) weaned while still at pasture nine to 13 days prior to housing and not transported or (4) weaned at pasture and transported. All calves were immunized with KLH at housing (day 0) and serum samples were collected subsequently to determine class and subclass anti-KLH antibody responses (IgG₁, IgG₂, IgA and IgM) by direct elisa. Increased anti-KLH IgG₁ and IgG₂ concentrations were shown in calves that were weaned prior to housing and transported on day 10 (P<0·05 and P<0·01 respectively). Transported calves had increased IgGI concentrations on day 20 (P<0·05) compared with calves that were not transported. However, calves weaned at housing and not transported had increased IgA and IgM responses on day 30 compared with the other groups of calves (P<0·05). This study shows that transportation and weaning affect the Immoral immune responses of suckler calves and that the effects persist for several weeks. However, the effects of the treatments were not consistent for all antibody classes measured.     

Oxidant stress in sled dogs subjected to repetitive endurance exercise

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 ? = 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.     

Ultrasonic observations on the turnover of ovarian follicular cysts and associated changes of plasma LH, FSH, progesterone and oestradiol-17β in cows

Changes in the diameters of individual follicular structures on ovaries were measured by transrectal ultrasonography for 29 to 40 days and the plasma concentrations of luteinising hormone (LH), follicle-stimulating hormone (FSH), progesterone and oestradiol 17β were determined in four cows with ovarian cysts. When these structures decreased in size, new follicular structures appeared and developed into cysts. Progesterone concentrations in plasma were below 1·0 ng ml⁻¹ during the experimental periods. Plasma concentrations of oestradiol-17β fluctuated. The mean concentration of oestradiol-17β in plasma differed (P<0·01) depending on the stage of the cyst. No preovulatory surges of LH were detected during the developmental stage of the cysts.     

Sustained strenuous exercise increases intestinal permeability in racing Alaskan sled dogs

We assessed gastric and intestinal permeability and performed gastroscopy to evaluate the effects of sustained strenuous exercise on the gastrointestinal tract in racing sled dogs. Three teams of racing Alaskan sled dogs were examined approximately 1 week before and 24 hours after the 2003 Iditarod sled dog race (1,100 miles in 10 days). Each examination consisted of the administration of a solution of sucrose, lactulose, and rhamnose to evaluate gastric and intestinal permeability, as well as gastroscopy to visually inspect the gastric mucosa. Of the 54 dogs examined before the race, 16 completed the course and contributed data to the analysis. Sustained strenuous exercise was associated with an increased frequency of gastric erosions or ulcerations seen endoscopically (0% prerace versus 61% postrace). A significant postrace increase occurred in the median lactulose to rhamnose ratio in both serum and urine (0.11 versus 0.165, P = .0363; 0.11 versus 0.165, P = .0090, respectively). No significant differences were found in median serum or urinary sucrose concentrations when pre- and postrace values were compared. No correlation was found between visible gastric lesions and the concentration of sucrose in serum or urine samples obtained 4-5 hours after administration of the sugar solutions. We conclude that sustained strenuous exercise is associated with increased intestinal permeability, but the sucrose permeability test as we performed it did not correlate with visible gastric lesions.     

Plasma Vitamin D Metabolites and C‐Reactive Protein in Stage‐Stop Racing Endurance Sled Dogs

Background

Dogs are a unique model for examining the effects of exercise on vitamin D status because of their lack of vitamin D synthesis by UV exposure. In addition, the inflammatory response may be associated with hypovitaminosis D.

Objectives

To investigate the effects of several days of endurance exercise on plasma vitamin D (25‐(OH)D₃, 24,25‐(OH)D₃ and 1,25(OH)D₃) and serum C‐reactive protein (CRP) concentrations in stage‐stop racing sled dogs.

Animals

12 racing sled dogs and 8 control dogs.

Methods

Blood was collected before the race and immediately after racing on days 2 and 8. Plasma vitamin D metabolites and serum CRP concentrations were measured.

Results

Racing dogs showed a significant increase in 25(OH)D₃ on day 2 (P = .027) and day 8 of the race (P < .001), whereas no increases were observed in control dogs. The plasma concentration of 24,25(OH)D₃ showed a significant increase by day 8 (P < .001). There were no significant changes in 1,25(OH) D₃ concentrations across all time points and groups. Racing dogs had significantly increased CRP concentrations by day 2 (39.3 ± 30.1 μg/mL; P < .001).

Conclusions and Clinical Importance

Increases in vitamin D metabolites as well as increases in CRP concentrations were observed in racing sled dogs. This finding was contrary to the hypothesis that decreases in vitamin D status in athletes may be related to the acute phase inflammatory response during exercise. In addition, the increased 24,25(OH)D₃ concentrations compared to what is observed in other species suggests metabolic variations in dogs that lead to enhanced disposal of vitamin D.     

Blood flow measurement to the duodenum,jejunum, ileum and caecum of conscious goats

Blood flow rates in ml/100 g tissue/minute to the duodenum, jejunum, ileum and caecum of conscious goats have been measured using radioactive microspheres (15±5 m diameter). The blood flow rates to these various sections of the intestine were significantly higher (P<0·001) under normal conditions than during epinephrine or norepinephrine infusions. Blood flow to the jejunum was also higher than that to the duodenum, ileum or caecum under normal conditions. The differences were found to be significant for duodenum and ileum (P<0·001), while non-significant for caecum (P>0·10).     

The Influence of High‐Intensity Moderate Duration Exercise on Cardiac Troponin I and C‐Reactive Protein in Sled Dogs

Background: C‐reactive protein (CRP) and cardiac troponin I (cTnI) are biomarkers of systemic inflammation and cardiac damage, respectively. Objective: To investigate the effects of short‐duration high‐intensity exercise on plasma cTnI and serum CRP concentrations in sprint racing sled dogs. Animals: Twenty‐two Alaskan sled dogs of 2 different teams participating in a 2‐day racing event. Methods: In this prospective field study, cephalic venipuncture was performed on all dogs before racing and immediately after racing on 2 consecutive days. Plasma cTnI and serum CRP concentrations were evaluated at each time point. Results: There was a mild, significant rise (P < .01) in median cTnI concentrations from resting (0.02 ng/mL; 0.0–0.12 ng/mL) on both days after racing (day 1 = 0.06, 0.02–0.2 ng/mL; day 2 = 0.07, 0.02–0.21 ng/mL). Serum CRP concentrations showed a mild significant increase (P < .01) on day 2 after racing mean (9.2 ± 4.6 μg/mL) as compared with resting (6.5 + 4.3 μg/mL) and day 1 after racing (5.0 + 2.9 μg/mL). Neither cTnI or CRP concentrations exceeded the upper reference range for healthy dogs. Conclusions and Clinical Relevance: Strenuous exercise of short duration did not result in cTnI concentrations above the reference range for healthy dogs. Although increased after 2 days of short‐duration strenuous exercise, CRP did not reach concentrations suggestive of inflammation, as reported previously in the endurance sled dogs. Therefore, we surmise that moderate exercise does not present a confounding variable in the interpretation of cTnI and CRP concentrations in normal dogs.     

Plasma‐Free Metanephrine and Free Normetanephrine Measurement for the Diagnosis of Pheochromocytoma in Dogs

Background

Measurement of plasma‐free metanephrines is the test of choice to identify pheochromocytoma in human patients.

Objectives

To establish the sensitivity and specificity of plasma‐free metanephrine (fMN) and free normetanephrine (fNMN) concentrations to diagnose pheochromocytoma in dogs.

Animals

Forty‐five client‐owned dogs (8 dogs with pheochromocytoma, 11 dogs with adrenocortical tumors, 15 dogs with nonadrenal disease, and 11 healthy dogs.)

Methods

A prospective study. EDTA plasma was collected from diseased and healthy dogs and submitted for fMN and fNMN measurement by liquid chromatography‐tandem mass spectrometry (LC‐MS/MS).

Results

Free MN concentration (median [range]) was significantly higher in dogs with pheochromocytoma (8.15 [1.73–175.23] nmol/L) than in healthy dogs (0.95 [0.68–3.08] nmol/L; P < .01) and dogs with adrenocortical tumors (0.92 [0.25–2.51] nmol/L; P < .001), but was not different from dogs with nonadrenal disease (1.91 [0.41–6.57] nmol/L; P ≥ .05). Free NMN concentration was significantly higher in dogs with pheochromocytoma (63.89 [10.19–190.31] nmol/L) than in healthy dogs (2.54 [1.59–4.17] nmol/L; P < .001), dogs with nonadrenal disease (3.30 [1.30–10.10] nmol/L; P < .001), and dogs with adrenocortical tumors (2.96 [1.92–5.01] nmol/L); P < 0.01). When used to diagnose pheochromocytoma, a fMN concentration of 4.18 nmol/L had a sensitivity of 62.5% and specificity of 97.3%, and a fNMN concentration of 5.52 nmol/L had a sensitivity of 100% and specificity of 97.6%.

Conclusions and Clinical Importance

Plasma fNMN concentration has excellent sensitivity and specificity for the diagnosis of pheochromocytoma in dogs, whereas fMN concentration has moderate sensitivity and excellent specificity. Measurement of plasma‐free metanephrines provides an effective, noninvasive, means of identifying dogs with pheochromocytoma.     

Serum Adipokine Concentrations in Dogs with Acute Pancreatitis

Background

Limited information is available about the role of adipokines in the development and progression of acute pancreatitis (AP) in dogs.

Objectives

To determine whether the circulating concentrations of adipokines differed between healthy dogs and dogs with AP, and whether the circulating concentrations differed between AP survivors and AP nonsurvivors.

Animals

Twenty‐eight healthy dogs and 25 client‐owned dogs with AP.

Methods

Prospective observational cohort study of 25 client‐owned dogs with newly diagnosed AP and 28 otherwise healthy dogs with similar body condition scores. The serum concentrations of leptin, adiponectin, resistin, visfatin, interleukin (IL)‐1β, IL‐6, IL‐10, IL‐18, and tumor necrosis factor (TNF)‐α were measured.

Results

The serum concentrations of leptin (P = .0021), resistin (P = .0010), visfatin (P < .0001), IL‐1β (P < .0001), IL‐6 (P = .0002), IL‐10 (P < .0001), and IL‐18 (P < .0001) were significantly higher in dogs with AP than healthy dogs, whereas the adiponectin concentration (P = .0011) was significantly lower. There were significant differences in the serum concentrations of leptin (P = .028) and adiponectin (P = .046) in survivors and nonsurvivors. After the disappearance of clinical signs, the concentrations of resistin (P = .037) and IL‐1β (P = .027) decreased significantly, whereas the serum concentrations of leptin (P > .999), adiponectin (P = .11), visfatin (P = .83), IL‐6 (P = .82), IL‐10 (P = .82), IL‐18 (P = .56), and TNF‐α (P = .94) did not differ significantly.

Conclusion and Clinical Importance

This study showed that dysregulation of adipokines might be involved in the pathogenesis of AP. In addition, leptin and adiponectin are likely to be associated with mortality rate in AP.     

Effects of dietary antioxidant supplementation on oxidative damage and resistance to oxidative damage during prolonged exercise in sled dogs

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 alpha-tocopherol acetate, 3 mg of beta-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 alpha-tocopherol, beta-carotene, and lutein. Plasma concentration of alpha-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.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

Immunolocalization of INSL3 in dog foetal Leydig cells and the LGR8 receptor in the gubernaculum testis

Oxidative stress parameters; thiobarbituric acid reaction substances (RBC-TBARS), catalase (RBC-CAT) and reduced glutathione (RBC-GSH)) and the intraerythrocytic concentrations of electrolytes; sodium and potassium (RBC-Na and RBC-K) were determined in 18 well- controlled (WC) and 22 poorly-controlled diabetic mellitus (DM). Dogs with DM had significant higher blood glucose concentration (P < 0.001), haemoglobin A1c (P < 0.01) and fructosamine (P < 0.001) compared to normal healthy dogs (n = 19). Diabetic dogs in both groups had higher RBC-CAT (P < 0.05) while RBC-TBARS were higher significantly only in poorly-controlled DM group (P < 0.05). The RBC-K was significantly higher in both DM groups (P < 0.001). No changes in RBC-GSH and RBC-Na were found between DM and control healthy dogs. By linear regression analysis, the relationship were found between degree of diabetic mellitus and RBC-CAT, RBC-TBARS, RBC-Na and RBC-K. The relationship was also found between oxidative stress parameters and intraerythrocytic K⁺. The results suggest that in diabetic dogs, oxidative stress occurs which related to the severity of disease and may affect potassium homeostasis.