What is the symbolism behind the cat in last week's episode?

I think the cat was just a device to remind Sayid of something else in his life, in the past. Think back to that time that Kate saw the horse on the island. I think maybe it's something like that. That seems to be something the island does often. Though I'm still trying to figure out all the symbolism of all the animals we have seen on the island to far. Is the appearance of the animals supposed to represt a change in something in the character's life while still on the islane? I feel like there isn't anything that happens on this show that dosen't have some sort of greater meaning. So far we have seen a polar bear, dog (Vincent), horse, cat....an I missing anything else?