What evidence showed that he had sympathy for dogs The Call of the Wild?

In "The Call of the Wild," Buck's sympathy for dogs is evident when he forms a deep bond with the other sled dogs, particularly with the gentle and loyal Spitz, despite their rivalry. His instinctual connection to his canine nature is highlighted when he shows concern for weaker dogs in the pack, often sharing food and protecting them during harsh conditions. Additionally, Buck's emotional response to the suffering of dogs, especially during brutal encounters with humans, further underscores his innate empathy for his fellow canines.