A 13-month old, intact female, miniature Schnauzer dog was presented with history of dermatitis, pruritus and pain of ear pinnae with delayed puberty. The basal serum growth hormone level was 0.01 ng/ml, which was much lower than the reference range (1.80-2.00 ng/ml). On the xylazine stimulation test, the dog was no responsive to administration of xylazine. The dog was diagnosed as isolated type pituitary dwarfism. Treatment was aimed to improve alopecia with oral melatonin. After initiation of treatment, alopecia of the ear pinnae has been improved.