Pituitary Dwarfism and Adrenocorticotropic Hormone Deficiency in a White Swiss Shepherd Dog With LHX3 Mutation.

LHX3 mutation in dogs is associated with combined pituitary hormone deficiency. However, ACTH secretion is usually preserved. A 9-week-old female White Swiss Shepherd dog presented with growth retardation and was diagnosed with pituitary dwarfism due to LHX3 mutation. In the 2 years after diagnosis, the dog developed persistent lymphocytosis and eosinophilia. Endogenous ACTH measurement, ACTH stimulation test, and CRH stimulation test confirmed pituitary hypocortisolism. The dog was administered physiological doses of prednisolone, with improvement of activity levels. These findings are similar to scarce human reports and suggest that corticotrope function might decline over time in dogs with LHX3 mutations. Awareness and screening for ACTH deficiency in dwarf dogs is important in light of compatible clinical signs and laboratory abnormalities, as treatment with glucocorticoids improves the quality of life of these dogs.