Poisons and other hazards.
Your puppy can be injured or poisoned. Of course, remove all the usual suspects, cleaners, chemicals, pesticides, insecticides, ELECTRIC CORDS! (block his access when removal is not possible) etc. Some things you may not think about, some house and yard plants are toxic. Charcoal briquettes that are self lighting are very toxic. Paints, varnishes, as well as fuels, oils, lubricants, antifreeze, waxes, and other automotive chemicals are hazardous.
More details here:
If your puppy eats or is exposed to something questionable, you can call The ASPCA Animal Poison Control Center which operates a hotline 24 hours a day, seven days a week at (888) 426-4435 for a fee of $50 per case. If you call, be prepared with the following information: the name of the poison your animal was exposed to and its amount and how long ago; the species, breed, age, sex and weight of your pet; and the pet's symptoms. You'll also be asked to provide your name, address, phone number, and credit card information. Their website is here http://www.aspca.org/site/PageServer?pagename=apcc
If you are the outdoors type of person you may have to deal with Poison Ivy or Poison Oak.