Addison’s disease (hypoadrenocorticism) is generally considered an uncommon disease in dogs and very rare in cats. Despite this, many veterinary practices have at least one or two Addisonian patients under management and we regularly diagnose cases at our hospital. The perceived prevalence is likely affected by improving veterinary knowledge and awareness of the condition.
Classic hypoadrenocorticism involves failure of the adrenal cortex to produce both mineralocorticoids and glucocorticoids. Mineralocorticoids (e.g. aldosterone) control the sodium and potassium concentrations. Glucocorticoids are essential for many metabolic actions such as gluconeogenesis, vascular tone and maintenance of gastrointestinal mucosa
Until now, Addisonian dogs in the UK have been managed with oral fludrocortisone acetate (Florinef) and usually additional prednisolone, particularly in times of stress. Florinef has now been discontinued and so it is in short supply. A generic form of fludrocortisone is available but it is several times more expensive and has unproven bioavailability.
Dechra have recently licensed an injectable mineralocorticoid – Zycortal (deoxycortisone pivolate). This drug is given by subcutaneous injection and has approximately 21 – 28 days’ duration of action.
It is crucial to be aware that Zycortal has only mineralocorticoid action. This means that even patients that were managed solely with Florinef will need additional glucocorticoids to keep them stable. Without the addition of prednisolone, Addisonian patients on Zycortal would be at risk of life-threatening Addisonian crisis.
The transition period to injectable DOCP therefore represents a potential risk for decompensation if not carefully managed. We have sadly already heard of patients decompensating during the transition, including one fatality. To help you to manage your patients in the longer-term we are offering internal medicine consultations specifically for managing the transition to injectable therapy. In addition to starting the injectable treatment, we will provide clear instructions for the client and referring vet on managing and monitoring the transition. After a smooth transition the patient would then remain under the primary vet’s care for ongoing treatment.
We hope that this service will reassure and benefit referring vets, clients and Addisonian patients alike.
If you would like to refer an Addisonian patient please complete the referral form as usual, marking the form as “Start Zycortal”.
This blog was written by Ben Harris, RCVS & European Veterinary Specialist in Internal Medicine.