Sprocker is tracking white lines

[Sprockermum]

Does anyone know why our sprocker follows the white lines on sport fields?
Does anyone elses dog do this?
He follows the white lines, nose down at full tilt....he looks like he's been sniffing a line of coke.
Thoughts welcome.

Sounds like he's just tracking whatever it is in the line (chalk/paint?). Probably quite a distinct smell for a dog. Unless something else walks along it and he's scenting that. Maybe the machine leaves a trace.

My sprocker has some neurotic tendencies too. She loves getting under our van, she comes out with her head covered in grease. Maybe it's a mineral thing with the machines that they like ? On the plus side I guess all the time your dog is following the lines he's not trying to sniff out real game, which has its advantages!