Cancer

Cancer in Rabbits

The 80% study is from one colony in 1958. New evidence shows it's much much less likely, and highly tied to genetics

gleaned from these looks like the initial 1950's study was based in ONE herd and in latter studies instances were all less then 40% total occurrence of cancer . And that included all forms of tumors present at time of death. And the numbers were rabbits who died WITH lesions. Not rabbits that died FROM lesions. its grievously dishonest to claim an 80% chance of specifically uterine cancer , when uterine cancer conservatively was14%. And mostly occurred in rabbits older then 6 years.

There are multiple studies and opinions now arguing against spaying female rabbits.

"In my practice, for all 53 entire does presented for which we had both an age at death and an entry in the clinical records about the death, age at death averaged 4.9±2.9 years (median 5.0 years). Of the 61 entire does older than six months that were examined at or within a few days before death, only three (ages 5.5, >6, and 7.2 years) had evidence of caudal or midabdominal tumours – each euthanased because of the tumours. For one case, ultrasonography indicated the tumour was uterine, the others were palpated only. For one additional rabbit (6.8 years) the vet queried whether she was palpating an abdominal mass or the caecum. No currently living does have evidence of abdominal masses. These ‘messy’ first-opinion data indicate that (i) only 10 to 13 per cent of entire does of 5.0 years or older had a clinically detectable abdominal mass consistent with a uterine tumour at the time of death, and (ii) if my practice had spayed these 61 does when young, we would have prevented uterine tumours in only three, possibly four (five to six per cent), of them. In other words, to prevent one case of uterine cancer we would have to spay 16 to 20 does. As Bradbury and Dickens emphasise, spaying has welfare costs and health risks. The anaesthetic-related death rate of healthy rabbits within 48 hours is 0.73 per cent (Brodbelt and others 2008) and rabbits can have longer-term morbidity and mortality as a result of adhesions – our practice has lost a rabbit to caudal abdominal adhesions strangulating the colon. At what number of young rabbit spays does the welfare cost equal the benefit of preventing one uterine tumour in an older doe? There are other reasons to spay rabbits, but after consideration, my policy is to discourage spaying of does, whether kept singly, with other females, or with neutered or entire males (in which case I encourage castration), unless there is a specific indication to do so." -Martin L. Whitehead, Chipping Norton Veterinary Hospital.

Whitehead is referencing "Should we advocate neutering for all pet rabbits?" By AG Bradbury, GJE Dickens, Veterinary Record, 2016.

A January 2022 study found only 9% adenocarcinoma present in their sample. Thier main findings were cystic endometrial hyperplasia. They acknowledge the study limitations.... and do not account for rabbits lacking a steady estrus cycle, therefore the endometrial lining would remain thickened on histology findings. https://www.sciencedirect.com/science/article/pii/S1557506322000015 cystic endometrial hyperplasia is not cancer, it's simply the endometrial lining being thick and proliferating cells... which would be normal given that rabbits are induced ovulators and their uterus needs to be in a constant state of conception readiness. The findings in this study are concurrent with the logic from Martin Whitehead's policy on not spaying, as you'd have to spay 20 young rabbits to prevent 1 case of adenocarcinoma in an older doe. Given the risks from anesthesia, both on the table and post surgical anesthesia induced GI stasis, post operative abdominal adhesions. The risk to benefit ratio weighs much higher on risk to female rabbits being spayed.

Neoplasia and Tumor-Like Lesions in Pet Rabbits ( Oryctolagus cuniculus): A Retrospective Analysis of Cases Between 1995 and 2019 Christof A Bertram 1, Beate Bertram 1, Alexander Bartel 1, Anja Ewringmann 2, Marco A Fragoso-Garcia 1, Nancy A Erickson 1, Kerstin Müller 1, Robert Klopfleisch 1 Affiliations expand PMID: 33213301 DOI: 10.1177/0300985820973460