In order to understand a little more about what ozone therapy is, you need to start with ozone itself. Ozone is simply a molecule that’s made up of three oxygen atoms – so it’s O3. The normal oxygen we breathe is O2, meaning ozone is just oxygen with an extra atom. Ozone has been used to treat conditions in humans for over 100 years, but more recently it’s being tried out as a therapy for pets, with great success.