A harness should fit comfortably but make sure you can pass two fingers between harness and body. Check carefully under the harness for redness or hair loss caused by an ill-fitting harness. Remember that puppies grow fast and their harness will need adjusting regularly and eventually replacing. WARNING: When using liquid flea treatments on your dog, remove their collar and harness as the chemical may react with the material and buckle. Please ensure you remove your dog's collar and harness before placing them into a pet crate. This harness should only be worn under supervision. Please examine this item for wear and tear, removing it if damage occurs. WARNING: CHOKING HAZARD. Pets can chew items unexpectedly. If that happens, please remove immediately, especially if the item is torn or damaged. Please seek veterinary attention if any material is ingested. Intended for dogs only.