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

BackgroundEarlier 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.MethodsThis study aimed to describe and compare macroscopic and histopathological alterations in uteri collected from domestic rabbits of various ages that were neutered, deceased, or euthanized without a suspected uterine disorder (NoUD; n = 94) and from rabbits with a suspected uterine disorder (UD; n = 22).ResultsIn 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 relevanceUterine 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.