Altered vitamin D status in liver tissue and blood plasma from Greenland sledge dogs (Canis familiaris) dietary exposed to organohalogen contaminated minke whale (Balaenoptera acuterostrata) blubber

• We conducted a controlled OHC exposure study on Greenland sledge dogs.
• We analyzed vitamin D in blood and liver tissue.
• Vitamin 25OHD3 was significantly lowest in liver tissue from exposed dogs.
• This may suggest OHC effects on immunity and reproduction in Arctic wildlife in general.

This study compared vitamin D3 (vitD3) and 25-OH vitamin D3 (25OHD3) status in Greenland sledge dogs (Canis familiaris) given either minke whale (Balaenoptera acuterostrata) blubber high in organohalogen contaminants (OHCs) or clean porcine (Suis scrofa) fat for up to 636 days. A group of six exposed and six control sister bitches (maternal generation) and their three exposed and four control pups, respectively, were daily fed 112 g whale blubber (193 µg ∑PCB/day) or porcine fat (0.17 µg ∑PCB/day). Mean level of ∑PCB in adipose tissue of exposed bitches and their pups was 3106 and 2670 ng/g lw, respectively, which was significantly higher than the mean concentration of 53 ng/g lw for all controls (p<0.001). The vitamin analyses showed that 25OHD3 in liver of maternal exposed bitches were significantly lower than in controls (p=0.004) while vitD3 was significantly highest in liver of exposed pups (p<0.003). Regarding blood plasma concentrations, exposed F generation pups had significantly higher concentrations of 25OHD3 than controls (p=0.009). Correlation analyses showed that blood 25OHD3 decreased significantly with increased adipose tissue concentrations of ∑PCB in exposed dogs (R2=0.64, p=0.005) and a similar trend was found for liver 25OHD3 (R2=0.32, p=0.08). The results indicate that the homeostasis and metabolism of vitamin D compounds may respond differently to the dietary composition of fatty acids and OHC exposure. It is unknown if the lower level of 25OHD3 in the liver of exposed dogs would have any negative effects on immunity and reproduction and more focus should be conducted on this compound in Arctic wildlife.