English Art/Literary Poetry & Literature

The wolf in front, obviously the leader, started to go around the sledge, making for the horse. It was some two meters away... Ivan stood up and, while holding on to the side of the sledge with his left hand, lashed the leader with his whip. It didn’t expect that, snapped at the whip with its teeth, and leaped to the side. It stumbled and fell back... The others ran into it from behind. The whole pack reassembled around their leader. It squatted on its haunches and lashed out with its fangs at first one, then another member of the pack. Then, springing forward once again, it easily caught up with the sledge. Ivan got ready and waited for his chance... He wanted to get the leader once more. But the leader began to go around the sledge at a greater distance. And another one pulled away from the pack and also started to go around the sledge – from the other side. Ivan clenched his teeth, grimaced... "This is the end. Death." He looked ahead.
"Sto-op!" He yelled. "Father!... Throw me an ax!"
Naum was whipping his horse. He glanced back, saw how the wolves were surrounding his son-in-law, and quickly turned away.
"Rob-bers! Thie-eves!"
"Slow down, we can beat ‘em back!... Slow down a little, you bastard!"
"Throw somethin’ at ‘em!" Naum shouted.
The leader came up alongside the horse, waiting for the right moment to pounce. The wolves who were bringing up the rear were very close now. The slightest pause and they would fly straight into the sledge – and that would be the end. Inan threw the small bundle of hay at them: the wolves didn’t pay any attention to it.
"Father, you sonuvabitch, slow down, throw me an ax!"
Naum turned around.
"Vanka!... Look out, I’ll throw it!"
"Slow down!"
"Look out, I’m throwing it!"
Naum tossed an ax to the side of the road.
Ivan judged the distance... He leaped out of the sledge and snatched up the ax... His jump startled the three wolves at the back of the pack, they leaped away and broke off their pursuit, intending now to rush at the man. But at that very instant, the leader, sensing a patch of packed snow beneath ***him, made his lunge.*** The horse shied to the side into a snowdrift. The sledge turned over: the shaft twisted the horse collar around, and put a stranglehold on the horse’s throat. The horse began gasping for breath, it struggled against the shafts. The wolf that had overtaken the victim from the other side sprang up under the horse and, with one swipe of its sharp-clawed paw, opened up the horse’s belly lengthwise.
The three remaining wolves rushed at the victim as well.
A moment later all five were tearing apart the flesh of the still quivering horse, dragging on to the blindingly white snow steaming tangles of bluish-purple intestines and growling. Twice the leader looked straight at the man with its yellow, round eyes.
Everything happened with such monstrous speed and ease that it all seemed more like a dream than reality. Ivan stood, ax in hand, looking in confusion at the wolves. The leader glanced at him once more... And that look – exulting, insolent – infuriated Ivan. He raised his ax, started yelling for all he was worth, and flung himself at the wolves. The reluctantly ran back a few paces and stopped, licking their bloodied chops. They did this so meticulously and with such absorption that it seemed the man with the ax didn’t interest them in the least. The leader, however, looked directly at Ivan, watchfully. Ivan cussed it out, using the most terrible words he knew. He waved the ax and took a step toward it... The leader didn’t budge. Ivan stopped as well.


Dear native English speakers!
Please help me understand why the wolf leader is first referred as "it", then as "he", and then as "it" again. What's the logic here, if any?
Thank you.