Having a pet is just like having a child in your home. You must take steps to ensure that your pet does not get into things. Some of these things that we see as not dangerous can be fatal to your pet.
Ensure that you do not have any strings that your animal can ingest. Also if you have a sewing kit or needles with thread make sure they are put away from your animals. It is very common for cats and dogs to ingest such things which can cause serious injury or death. If your animal ingests a string or other foreign object and you don't know and then see it coming from his anus do NOT pull it out. This could cause serious injury to your pet. If it is string or small twine, trim it with sharp scissors. If you are concerned you should call your veterinarian.
Make sure your pocket change is picked up, along with small objects that might be swallowed by your pet. Dogs are well known for swallowing balls that are too small as they play with them. Make sure if you give your dog a ball, that it is large enough that it can't swallow it. Cats have been known to swallow pocket change and other small objects. Any of these objects can cause an obstruction in the digestive tract. Intestinal obstructions are serious and have caused many deaths in animals.
Ensure that the plants you have in your home are not toxic to your pet. Many house plants are toxic to both cats and dogs and if ingested will cause death. See here for a list of some of the more common toxic plants.