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

Abstract

BackgroundDogs 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.ObjectivesTo 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.Animals12 racing sled dogs and 8 control dogs.MethodsBlood was collected before the race and immediately after racing on days 2 and 8. Plasma vitamin D metabolites and serum CRP concentrations were measured.ResultsRacing 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 ImportanceIncreases 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.

Influence of Various Factors on Circulating 25(OH) Vitamin D Concentrations in Dogs with Cancer and Healthy Dogs

“…This may be true for all dogs, but studies confirming this finding in other breeds are needed. Additionally, 24,25(OH) 2 D concentrations in dogs appear to be much higher than those reported in humans and other species . This observation is most likely a consequence of higher dietary vitamin D intake in dogs through the consumption of commercial dog foods fortified with vitamin D. The relationship between dietary vitamin D intake and plasma 25(OH)D may be harder to quantify in dogs that are receiving amounts of vitamin D over intake requirements.…”

“…Factors shown to influence blood 25(OH)D concentrations in humans include the following: sex, sex hormone concentrations, age, race, body condition score (BCS), muscle condition score (MCS), dietary vitamin D intake, blood ionized calcium concentrations (ICa), and blood parathyroid hormone concentrations (PTH) . Additionally, blood concentrations of another vitamin D metabolite, 24,25(OH) 2 D, have been reported to be much higher in dogs than in other species . Thus, activity of the 25‐hydroxyvitamin D‐24‐hydroxylase enzyme (CYP24A1), which is responsible for converting 25(OH)D to 24,25(OH) 2 D, may be an important factor determining blood 25(OH)D concentrations.…”

Beyond the skeleton: the role of vitamin D in companion animal health

“…A recent study has found that plasma concentrations of 24,25(OH)D 3 , an excretory metabolite of 25(OH)D, were higher in dogs than in humans, pigs and rodents indicating that the metabolism of 25(OH)D may be different between dogs and other species (Spoo et al . ). The nuclear VDR is the ligand‐dependent transcription factor that mediates the action of its natural ligand 1,25(OH) 2 D (Vanherwegen et al .…”

“…, Spoo et al . ). There is a need to further clarify whether vitamin D deficiency is a cause or consequence of inflammation in companion animals.…”

“…2013 ). A recent study has found that plasma concentrations of 24,25(OH)D 3 , an excretory metabolite of 25(OH)D, were higher in dogs than in humans, pigs and rodents indicating that the metabolism of 25(OH)D may be different between dogs and other species (Spoo et al . 2015 ).…”