Abstract
The reproductive cycle in domestic dogs involves prolonged phases of hormonal activity, making the endometrial tissue vulnerable to degenerative changes. One common result of these changes is cystic endometrial hyperplasia (CEH), which often leads to pyometra. Another, though rarer, condition is pseudo-placentational endometrial hyperplasia (PEH), characterized by abnormal proliferation of the endometrial glands and stroma, forming placental-like structures without the presence of pregnancy. Case presentation: An 8-year-old female Golden Retriever, healthy and intact, was presented for a routine ultrasound examination to confirm pregnancy after natural breeding 25 days earlier. Two previous pregnancies of this bitch have resulted in small but live litters. The ultrasound examination revealed multiple bilateral thickenings of the uterine horns, with ampullary-shaped enlargements measuring approximately 2.5 × 3.0 cm 25 days after breeding. The endometrium was conspicuously thickened, hypoechogenic, and either homogeneous or with scattered hyperechoic markings and faint striations. The mucosal surface ranged from regular to slightly irregular, and a small amount of hyperechoic condensed fluid was present in the lumen of the horns. No embryos were observed. Based on these findings, two primary diagnoses were considered: PEH or embryonic resorption sites, with a possible segmental uterine inflammation. A diagnosis suggestive of PEH was established through histopathological examination of the uterus after ovariohysterectomy, supported by consistent ultrasound findings that showed no progression or changes over time.