In addition to a small quantity of your pet's regular medications, keep styptic powder, diphenhydramine, and sugar tablets in the pet first aid kit. Styptic powder stops bleeding in cases of minor cuts or torn nails; diphenhydramine (or Benadryl) is an antihistamine that can be used temporarily for mild allergic reactions; and sugar tablets can help a diabetic pet or a small pet with low blood sugar.
Hydrogen peroxide can also be kept in a dog first aid kit, as it can inducing vomiting and help get rid of ingested toxins or foreign objects. However, this should only be under the direction of a veterinarian, as some toxins or materials will cause more harm if they are vomited up. Additionally, hydrogen peroxide should never be given to a cat.