Cushing disease itself can cause elevated WBC, so this may not necessarily be related to an infection. Certainly a year of antibiotics should have taken care of most infections, depending on what antibiotic was used. Unusual infections or internal infections (eg, abscess in a muscle or organ) might cause a persistent elevated WBC, as might a chronic inflammatory condition. You would probably be having other symptoms, such as persistent fevers, pain, or weight loss, if that were the case. You don t say how high the WBC count is, so it is hard to assess its severity. Be sure the Cushing disease is well treated first. If you are still having elevated WBC, you might need further evaluation or need to see a hematologist to get a specific diagnosis. Hope this helps.