As much as your dog or cat may beg for some of your Halloween candies, always remember that chocolate is deadly to them in any amount. There's a chemical that naturally occurs in chocolate that they cannot tolerate.
 

If you work in a pet store, remember that this is the time of year that can be deadly for black cats. Some sick people who play at being what they'll call a Satanist will buy them to "sacrifice" If you can, don't take any black cats or sell them during October. Many pet stores won't take them anyway, just for this reason.

The wrappers, such as tin foil, can get stuck in your pets' digestive tract and make them ill or cause death. There are plenty of recipes for making homemade dog and cat treats, you can always make them on a Halloween theme if you want to make something special for your pet.

Large dogs can have lethal tails when it comes to wagging them. I've seen a German Shepherd clear a coffee table in two seconds flat when excited. Don't leave any lighted candles or Jack-O-Lanterns where they could be knocked over by a swinging tail or by a curious cat. Not only could your pet start a fire but they could severely burn themselves in the process.

If you are going to dress your pet in a costume, keep in mind that unless the dog or cat is extremely receptive to this kind of thing, you could be causing it discomfort and stress. Some animals don't mind at all but others do not want to be bothered with this kind of thing. They'll be under enough stress with the festivities going on outside and people constantly at the door so don't cause them any more stress then you have to. You may love to dress in costume but then, you aren't a dog or a cat.

If a pet costume comes with a mask, don't use it. While some dogs will love dressing up, they usually aren't too keen on masks. If you do use a mask on your pet, make sure that it's eyes have plenty of room to see and that there is nothing covering its nose or confining it's mouth.

If you are having an indoor party, make sure that you put your dog or cat in a room where they won't be disturbed. Even if your pet is ultra friendly and doesn't mind loud noises, music and lots of people you should keep them separate for the night. Also, be careful your cat or dog doesn't dart out through the open door as you hand out candy. Best bet is to just put them in a room with some food and water for the night and check on them once in a while to let them know everything is fine.