Treatment of a non-responsive eosinophilic vasculitis in a dog with low-dose radiotherapy and Oclacitinib : a case report

An eosinophilic vasculitis is an inflammatory process in the vessel wall that leads to bleeding, ischemia, and necrosis in the surrounding tissue. For the treatment of eosinophilic diseases, it is necessary to identify and eliminate the underlying cause. If no cause can be found, symptomatic treatment with immunosuppressants such as glucocorticoids, cyclosporine, and azathioprine is administered. However, eosinophilic lesions often do not respond to therapy or recur after treatment has ended. In this case report, eosinophilic vasculitis was diagnosed in the caudal oral cavity of a six-year-old spayed female mixed-breed dog. Various treatment approaches using different immunosuppressants, antibiotics, and NSAIDs only led to temporary improvements in the clinical condition. Therefore, low-dose anti-inflammatory radiotherapy was proposed, as it can achieve immunomodulatory and anti-inflammatory effects and has already shown success in the irradiation of other chronic inflammatory diseases in small animals, such as canine osteoarthritis. In human medicine as well, low-dose radiation therapy is an established method for treating chronic inflammatory diseases. The anti-inflammatory radiotherapy was administered at a total dose of 12 Gy over four days, with a single fraction dose of 3 Gy. In addition to radiotherapy, the patient was treated with oclacitinib for three months. The combination therapy led to a rapid clinical improvement with regression of the intraoral eosinophilic lesions. This clinical remission persisted over an observation period of eight years without recurrence. Anti-inflammatory radiotherapy in combination with oclacitinib represents a promising approach for the treatment of therapy-resistant eosinophilic vasculitis. Further studies are warranted to confirm the therapeutic outcome and to evaluate whether radiotherapy or oclacitinib as monotherapy can achieve a comparable therapeutic effect to their combination.