All horses have a line they'll refuse to cross - and I suspect that means more bad news awaits Shishkin

I once had a horse who refused to go near pigs. No amount of patience or cajoling over the years could ever convince him those mud-covered monsters were anything but hellbent on hunting him down and taking him out, even when separated by hundreds of metres and extensive fencing. Once it was in his head, the matter was settled and pigs were forever public enemy number one.

Nearly every rider will have a tale of their own about a red line their horse refused to cross, be it a particular object, noise or even those pesky farm animals to bring out the dreaded stubbornness of their ride. Thankfully pigs are easy enough to avoid, but the doggedness of horses can present itself in significantly more inconvenient ways, as seen by Shishkin's exploits at Ascot last week.

He is not the first racehorse – and will certainly not be the last – whose refusal to run has come seemingly out of the blue. As he planted his feet and swung his head to watch the 1965 Chase field set off to do what he would not, Shishkin joined a notorious list of runners to have made headlines for entirely the wrong reasons – and history tells us we might not have seen the last of his troublesome behaviour.