Prospective survey of neoplastic and non-neoplastic uterine disorders in 116 domestic rabbits (Oryctolagus cuniculus)

Abstract

Background: Earlier studies indicate that the risk for uterine tumours in rabbits may be as high as 60–80%. This high occurrence and the need for routine neutering of non-breeding pet rabbits have recently been in the spotlight. Methods: This study aimed to describe and compare macroscopic and histopathological alterations in uteri collected from domestic rabbits of various ages neutered, deceased, or euthanized without a suspected uterine disorder (NoUD; n = 94) and from rabbits with a suspected uterine disorder (UD; n = 22). Results: In the NoUD group, uteri of 41 rabbits (44%) displayed histopathological findings and 12 rabbits (13%) had neoplasms. Samples from thirteen rabbits (14%) evinced histopathological findings with no macroscopic alterations. The most frequent diagnoses were cystic endometrial hyperplasia (26% of the 41 uteri), adenocarcinoma (9%), and polyps (5%). In the UD group, uteri from 21 (95%) out of 22 rabbits exhibited pathological alterations; in 2 (10%) of these, the changes (cystic endometrial hyperplasias) were seen only in histology. The most frequent diagnoses in the uteri of the UD group were cystic endometrial hyperplasia (77%) and adenocarcinoma (54%). Uterine malignant neoplasia affected 40% of all rabbits aged over 3 years, and the odds of a malignant uterine tumour in these rabbits were approximately 19-fold higher than in rabbits aged under 3 years. Conclusions and clinical relevance: Uterine disorders are common in domestic rabbits, even without a suspected uterine disease, and the risk of uterine neoplasia markedly increases after 3 years of age. A macroscopically normal uterus may have pathological changes and ovariohysterectomy should be therefore preferred over ovariectomy at least in older rabbits.