Each creature in the wilderness boasted a unique, often challenging, bonding ritual. Take the Tiaks, for instance, where one had to forcefully mount its back to establish a 'tame' it and form a partnership with the beast.
Adrian had accomplished that part. Unfortunately, the Tiak still refused to acknowledge him as its master and got heavily injured in the process. Adrian might have been safe, but Huruk wasn't.
While Suhi rushed towards 'Milka' to check on his son, Skaha did the same for Huruk. The beast was alive but had severely injured itself. It had a massive dent on its forehead, and its neck was slightly swollen.
It wasn't something Skaha couldn't deal with in time and help Huruk heal, but he was confident that the beast would never be the same. As such, he had no use for Huruk.
"...forgive me for this," Skaha mumbled, getting up and placing the edge of his staff on Huruk's neck before twisting it with all his weight.