I've seen some in real as well while driving through an industrial area. I believe it's the effect of chemical hue and temporary. It's not serious for dogs. Also it's not from inside but because dogs go and sit ihe water that's flowing out of copper factories. Not dangerous for animals.

Coinsreporter

No! This is more interesting. 
Edit: Oh, it's also as a result of chemical pollution? 

siggy47

Dogs_And_Cats

Experts Baffled By Blue Dogs

Thanks for sharing. 
Have you not listened that Blue Dogs are not very rare in India.
https://youtu.be/Y69ri7_TiZQ?si=66SHTle_yRqQ_5zQ