Association of Pseudoplacentational Endometrial Hyperplasia and Pyometra in Dogs.

Uterine inflammation is the most common and clinically relevant genital change in bitches. The aim of this study was to evaluate the association between uterine hyperplasic lesions and uterine inflammation. Uteri and ovaries from 200 bitches were sampled after elective or pathological ovariohysterectomy and histologically evaluated. Endometrial hyperplastic lesions were classified as cystic endometrial hyperplasia (CEH) or pseudoplacentational endometrial hyperplasia (PEH), whereas cases of uterine inflammation were subdivided into endometritis or pyometra. The frequency of PEH (79.4%) was significantly higher (P <0.05) than CEH (20.6%), whereas 17.5% of the animals did not have any endometrial hyperplasic lesions. There was a statistically significant association between the frequency of PEH and uterine inflammation (P <0.0001) and PEH was also significantly associated with pyometra (P <0.05). There was no significant association between CEH and uterine inflammation. There was a significant association between dioestrus and the frequencies of PEH, CEH, uterine inflammation and pyometra. However, there was no significant association between endometritis and dioestrus. These results support the recommendation that the terms 'cystic endometrial hyperplasia', 'pseudoplacentational endometrial hyperplasia' and 'pyometra' should be used separately, instead of the classical term 'cystic endometrial hyperplasia-pyometra complex'.