Each to their own but essentially not true.
Also. From the BBC.
What about safety? Significant changes were introduced before the 2013 race which saw the core of fences softened, the distance reduced and new procedures for loose horses. There was one equine fatality in the race last year - the first from a total of 276 runners in the past seven editions.
Yeah its a common misconception in recent years. It took far too long for them to listen to calls from the outside sadly. Its telling once they softened the fences, reduced the distance, horses stopped dying. The brutal reality is that up until 2013 those complaining about animal welfare were 100% right. The horses were tired, jumping huge obstacles, and as a result fatalities were occurring. The unfortunate thing is that the time taken to change has left a stigma attached to the race - horse racing has to accept responsibility for that. Horses do die in the course of racing. Its not nice and for some even 1 death will always be unpalatable regardless if this is what the animals are bred for.