Swiffer Wet Jet products do not contain cleaning agents in large enough quantities to be a serious hazard for pets. Several years ago, an urban legend spread that it contained toxic antifreeze and killed a dog. This rumor is completely unfoundedour toxicology experts evaluated the product and determined it doesn't contain ethylene glycol from antifreeze, and is appropriate to use in homes with pets.
Like any product, however, it's important to read and follow label instructions to avoid unnecessary exposure. For Swiffer Wet Jet and other cleaning products, mild skin irritation or stomach upset may occur if pets walk through a still-wet floor or lick any spilled solution.