RESUMO
A 5-year-old, clinically normal intact female Miniature Schnauzer was presented for demonstrative ultrasonography in a seminar. She had two pregnancies in the past and had a natural mating 2 months previously. Ultrasonography revealed a segmental and circumferential mural thickening of the right uterine horn. The endometrium was markedly thickened with multiple organized hyperechoic linear striations, perpendicular to the mucosal surface. Histology revealed focal endometrial hyperplasia resembling the maternal tissue of the normal canine placenta. A diagnosis of spontaneous pseudo-placentational endometrial hyperplasia (PEH) was made. This study described a unique ultrasonographic appearance of PEH, which may facilitate the diagnosis of PEH.