I can't find it but there was some more research done on 2011/2012 which monitored tendon heat under the support type wraps and showed it reached dangerous levels.
Well thats what lots of vets said anyway, I can't find the artice though.
Raf you're right they don't ride bikes nor do they swim (although I did have one horse who loved to go swimming) so it must be the running in thermals that does it!