Iatrogenic Hyperadrenocorticism in a Cat following a Short Therapeutic Course of Methylprednisolone Acetate

Abstract

Iatrogenic hyperadrenocorticism (or iatrogenic Cushing's syndrome) is an adrenal disorder that may result from long-term administration of glucocorticoids for therapeutic purposes, most often given to treat allergic or immune-mediated disorders. Prolonged treatment with synthetic glucocorticoids can suppress hypothalamic corticotrophin releasing hormone and plasma adrenocorticotrophic hormone (ACTH), thus causing a functional inactivity of the adrenal cortex. The result is a clinical syndrome of hyperadrenocorticism but with basal and ACTH-stimulated plasma cortisol concentrations that are consistent with spontaneous hypoadrenocorticism (Addison's disease). Whilst iatrogenic hyperadrenocorticism is relatively frequent in dogs, the diagnosis of iatrogenic hyperadrenocorticism in cats is very uncommon because this species has been found to be remarkably resistant to prolonged administration of glucocorticoids. To the author's knowledge, there are only two published clinical cases of feline iatrogenic Cushing's syndrome. This report describes a case of iatrogenic hyperadrenocorticism in a cat, and shows how normalisation of the adrenal function was achieved with supportive treatment and withdrawal of glucocorticoid administration.

Hyperadrenocorticism in Cats

“…A small number of privately owned cats treated with exogenous glucocorticoids had "clinical iatrogenic FCS" and were reported (Green et al, 1995;Schaer and Ginn, 1999;Ferasin, 2001;Lien et al, 2006). Among the features likely due to chronic glucocorticoid exposure were abdominal enlargement, muscle wasting, poor hair coats, and skin fragility.…”

Glucocorticoid Therapy

“…Associated signs occur most often after repeated injections of long-acting glucocorticoid preparations; however, occurrence of signs (e.g., polyphagia and weight gain) have also been reported after a single injection of methylprednisolone acetate (Ferasin, 2001). Associated signs occur most often after repeated injections of long-acting glucocorticoid preparations; however, occurrence of signs (e.g., polyphagia and weight gain) have also been reported after a single injection of methylprednisolone acetate (Ferasin, 2001).…”

“…Oral, parenteral, and topical administration all lead to HPA axis suppression, which is most serious and prolonged after repeated injection of long-acting preparations (waterinsoluble esters). In a cat treated with subcutaneous (SC) methylprednisolone acetate (20 mg) weekly for 4 weeks, complete suppression of the HPA axis was still seen 1 month after the last injection (Ferasin, 2001). A dog that was treated for pruritus with a similar single dose of methylprednisolone acetate experienced HPA axis suppression for 7 weeks (Meyer, 1982).…”

Cortisol influence on testicular testosterone secretion in domestic cat: An in vitro study

“…Despite evidences that stress exerts influence on reproductive functions, the interactions between the hypothalamus-pituitary-adrenal (HPA) and gonadal (HPG) axes remain unclear (Moberg 1991, Baldwin et al 1996, Fenske 1997, Ferasin 2001, Genaro et al 2003, Lacerda Neto et al 2004, Bridges et al 2005). There are indications of both inhibiting (Bambino & Hsueh 1981, Welsh et al 1982, Genaro et al 2003 and stimulating (Faulborn et al 1979, Welsh & Johnson 1981 effects of the HPA axis on HPG.…”