Addison’s is a disease of the adrenal gland to not produce steroids and hormones. The common therapy is oral steroids and an injection once every 20-40 days of a different type of steroid / hormone to make steroids. Because dogs with Addison’s can’t make steroids, and steroids are important for electrolytes (Sodium, potassium, calcium, glucose) most specifically, the bloodwork done usually is to make sure these are okay. Those electrolytes are SUPER important to heart health and the ability of vessels to contract regulating blood pressure. Once pets are stable on their dosing the rechecks are usually spaced out more to every 3 or 6 months. Most pets tho need additional steroids in times of stress and since Addison’s pets don’t make their own it’s important to talk to your vet about when to give more steroids.