She suffered severe ligament damage in a fall from Hello Sailor in the grand prix last month.
One of the horse’s studs penetrated her Achilles tendon.
“It’s a case of resting and trying to get the swelling down,” said Tina, who is on crutches.
“The aim is to be back before Olympia and start jumping again by early December.”
Olympia, the London International Horse Show, runs from 17-23 December