Hector was Muddy's dog that accompanied them on the travels through the Eye of the Forest. He was able to detect strange occurences, such as when the other large animals attacked and when he noticed something strange about Zadie Eloko (of course this could just be him randomly barking about Zotz). However, Muddy was upset with him when he chewed holes in the tent, allowing them to get wet by the rain, weakening their Neshamah.
Eventually he plays a crucial role as John was able to find out what happened to Philippa and the others by accessing the memories of Hector. Prior to the second Indian attack by the Xuanaci, Hector had strayed from the group where John finds him.
As Hector, he was able to sneak into the Indian village unnoticed. As the Indian tribe was about to kill the second jaguar that Nimrod had be transubstantiated in John was able to intervene.
After reclaiming his own body, Hector returned to his normal state and started licking John while showing suspicion for the rival Prozuanaci Indian tribe. Meanwhile, the Indians had begun throwing rocks at him when he had got to close.