Bitter Spray is spray used to deter puppies and dogs from chewing on inappropriate things. The spray has a bitter taste that most dogs find unpleasant. To use this type of chewing deterrent, spray on all items you wish the dog to avoid. These sprays come in many different kinds, and even come in a paste form. These products are non-toxic, but can sometimes evaporate quickly, and must be reapplied regularly. Not all dogs will be repelled by bitter sprays.