Just for future readers - as @Jealoushe says, this thread has been pretty carefully cultivated over several years at this point - it’s important to clarify that while sad, this wouldn’t have been a career ending injury but for the horse’s age and history.
Shammie is unfortunately a historically difficult horse to keep sound (as evidenced by some very careful management since WEG in 2014), and now at the age of 16 there just isn’t any point bringing him back from this to the top level when it’s clear his body struggles to keep up with his heart. A strained tendon, no matter how rare the location, can be season-ending but is unlikely to be career ending in most other circumstances.
The good news, of course, is that he should be very able to enjoy a long and comfortable retirement I wish the same could be said for every horse that left the box on Saturday.