Embryo recovery rate in a mare affected by Cushing's syndrome

Equine Cushing’s syndrome usually induces an increased secretion of cortisol due to a marked overproduction of ACTH, generally resulting from an adenoma of the pars intermedia of the pituitary gland. Equine Cushing’s syndrome occurs primarily in aged females (19–21 years old) (Boujon et al., 1993). Affected horses show: weight loss, polyuria, polydipsia, hyperhydrosis (Thompson et al., 1995), hirsutism, shaggy coat and dry skin. Cushing’s affected animals often appear ‘sway-backed’ and ‘potbel- lied’ with loss of muscular mass, especially from dorsal epaxial and gluteal muscles. Many affected horses show recurring and systemic skin infections and/or chronic laminitis. These conditions are due to the increased susceptibility to infections caused by the immunosuppressive status as a result of increased cortisol secretion and hyper- glycaemia (Field and Wolf, 1988; Hillyer et al., 1992). Another clinical sign related to an increase of cortisol is inhibition of physiological ovarian activity (Love, 1993). Embryo transfer is a technique applied, in the horse, to attempt to have foals from mares that cannot carry a normal pregnancy due to their health conditions (Squires, 1993). The purpose of this work was to describe the use of a Cushing’s disease affected mare as an embryo donor in the context of an embryo transfer programme.