I’m pretty sure the threats were mentioned in the interview posted by @wanderlust at https://www.youtube.com/watch?v=Szk4oSp_Rd4
Also, is it truly more common in WBs? That interview and related articles have cited rates of 38–50% in thoroughbred remains studied, though I do wonder if the samples may be biased. I haven’t seen mention of the rate in WBs.