In the majority of dogs with primary hypoadrenocorticism (PH), the disease is characterized by an absolute deficiency of glucocorticoids and mineralocorticoids. Consequently, those patients require life-long replacement of both hormones. Since application of the respective drugs do not restore physiological hormone levels and biorhythm, overdose may be possible during long-term management. Unlikely to glucocorticoid excess, overdose of mineralocorticoids may go clinically unnoticed. Due to their role as key mediators for renal damage and progression of kidney disease, mineralocorticoid overdose represents a matter of concern.

The aim of the study was to investigate kidney function by means of SDMA and creatinine (Cr) in dogs with PH during long-term mineralocorticoid therapy.

Twenty-seven client-owned dogs with PH receiving either desoxycorticosterone pivalate (DOCP) or fludrocortisone acetate (FC) for a minimum of 12 months were included in the study. Concentrations of Cr had been measured during regular re-evaluations and were retrieved from the medical records retrospectively. SDMA was measured using the validated immunoassay at the reference laboratory (IDEXX Diavet).

Treatment time ranged from 12–146 months (median 47). Nine dogs had been treated with FC, 8 dogs with DOCP and in 10 dogs FC had been changed to DOCP because of poor response or adverse effects. At the time of diagnosis 3 dogs had elevated SDMA whereas Cr was elevated in 8 dogs, both parameters normalized after starting therapy. Two dogs developed persistent elevated SDMA 18 and 32 months after starting therapy with FC and DOCP respectively, followed by an elevated Cr 14 and 4 months later. Clinical signs and further work up were consistent with chronic kidney disease (CKD) in both dogs. Although SDMA was within the reference interval in all other dogs, 3 dogs showed an elevated Cr, being permanent in one of them. A significant correlation between SDMA and Cr was demonstrated (r=0.35; p=0.0013). There was no statistical evidence of any differences in Cr or SDMA between the FC and the DOCP groups.

In conclusion, selected dogs may develop CKD during long-term mineralocorticoid therapy. The prevalence of CKD in PH might be higher than in the general dog population, however this has to be verified in a larger number of dogs. The significance of an elevated Cr with normal SDMA is unclear, possibly reflecting prerenal azotemia or early kidney dysfunction.

Disclosures

Disclosures to report:

CR was consultant for Boehringer Ingelheim and Novartis Animal Health and is currently consultant for Dechra Limited. She has received financial support for her endocrine research from various companies such as Nestlé Purina, Hills, Provet, Antlia SA, Glycemicon and from the clinical studies fund of the ECVIM-CA and from the Society of Comparative Endocrinology. NSR has been member of the Vetoryl novel monitoring meeting 2017 organized by Dechra Veterinary Products Ltd.