Difference between revisions of "Cancer"

From Bun Club Wiki
Jump to navigationJump to search
Line 1: Line 1:
Cancer in Rabbits
= 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
'''Cancer in rabbits''' (''Oryctolagus cuniculus'') has been a subject of veterinary research for decades. Earlier claims suggested extremely high risks of uterine cancer in intact female rabbits, most prominently an oft-cited 1958 colony study reporting rates approaching 80%. However, modern evidence demonstrates that such claims were overgeneralized and based on a limited genetic pool. Contemporary studies show that the actual risk of uterine adenocarcinoma is substantially lower, highly dependent on age and genetics, and must be weighed against the surgical risks of spaying.


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.
== Neutering of Pet Rabbits ==
Veterinary debate continues over whether routine spaying of all female rabbits should be recommended. 
A 2016 article by Bradbury and Dickens questioned whether universal neutering was in rabbits’ best interest, noting that while spaying prevents uterine adenocarcinoma, it carries welfare and surgical risks.<ref>Bradbury, A.G., and G.J.E. Dickens. "Should we advocate neutering for all pet rabbits?" ''Veterinary Record'' 179, no. 24 (2016): 654–655. https://pubmed.ncbi.nlm.nih.gov/28008120/</ref> 


There are multiple studies and opinions now arguing against spaying female rabbits.  
In response, some veterinary associations, such as the RWAF and BVZS, defended routine spaying, citing risk reduction. Yet first-opinion practice data, such as those reported by Martin Whitehead (2015), suggest that only 10–13% of does over 5 years old presented with uterine masses, meaning that 16–20 spays would be needed to prevent a single case of uterine cancer.<ref>Whitehead, Martin L. "Letter: Rabbit health." ''Veterinary Record'' 180, no. 3 (2017): 77. https://www.tesble.com/10.1136/vr.j826</ref> 


"In my practice, for all 53 entire does
== Should We Advocate Neutering for All Pet Rabbits? ==
presented for which we had both an age at
Bradbury and Dickens emphasized that universal spay policies may not be justified, particularly in single-housed rabbits where social stress and pregnancy risk are absent. They highlighted the need to balance welfare costs, anesthesia risks, and potential benefits.<ref>Bradbury, A.G., and G.J.E. Dickens. "Should we advocate neutering for all pet rabbits?" ''Veterinary Record'' 179, no. 24 (2016): 654–655.</ref> 
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.  
== Prospective Studies ==
Recent prospective and retrospective studies have provided more detailed prevalence data:
* A 2022 Finnish prospective study (Mäkitaipale et al.) found only 9% adenocarcinoma among 116 rabbits, with the most common finding being cystic endometrial hyperplasia (a benign thickening of the uterine lining common in induced ovulators).<ref>Mäkitaipale, J., N. Airas, S. Engblom, and J. Lindén. "Prospective survey of neoplastic and non-neoplastic uterine disorders in 116 domestic rabbits (Oryctolagus cuniculus)." ''Veterinary Pathology'' 59, no. 1 (2022): 78–87. https://doi.org/10.1016/j.jcpa.2022.01.001</ref> 
* Walter et al. (2010) reported 59 cases of uterine disease over 7 years, of which 29 were adenocarcinomas.<ref>Walter, B., et al. "Uterine disorders in pet rabbits: a retrospective study." ''Journal of Exotic Pet Medicine'' 19, no. 1 (2010): 18–23.</ref> 
* Künzel et al. (2015) examined 50 cases of uterine disease and found 27 adenocarcinomas.<ref>Künzel, F., et al. "Disorders of the uterus in pet rabbits: a histopathological study." ''Tierärztliche Praxis'' 43, no. 1 (2015): 35–40.</ref> 


While these reports document uterine neoplasia, incidence rates in the general rabbit population remain unclear because the baseline population size is unknown. Most affected rabbits were 5–7 years old, suggesting that age is a primary risk factor.


https://www.tesble.com/10.1136/vr.j826
== Neoplasia and Tumor-Like Lesions ==
Letters
A 2020 retrospective analysis by Bertram et al. of rabbit necropsy cases from 1995 to 2019 reported a variety of neoplasms, including uterine adenocarcinomas but also tumors of the skin, kidneys, and hematopoietic system.<ref>Bertram, C.A., et al. "Neoplasia and tumor-like lesions in pet rabbits (Oryctolagus cuniculus): A retrospective analysis of cases between 1995 and 2019." ''Veterinary Pathology'' 58, no. 6 (2020): 1032–1042. https://doi.org/10.1177/0300985820973460</ref> 
rabbit heath
===Neutering of pet rabbits===
BRADBURY and Dickens (VR, December
24/31, 2016, vol 179, pp 654-655)
question whether vets should advocate
neutering all pet rabbits and conclude that
that recommendation may not be optimal
for the welfare of single-housed rabbits.
Saunders and Stidworthy of the Rabbit
Welfare Association and Fund (RWAF)
and British Veterinary Zoological Society
(BVZS), disagree (VR, January 21, 2017,
vol 180, p 77). For does, a large part of
Saunders and Stidworthy’s argument is
that, although uterine adenocarcinomas
may not be as common in pet rabbits
as historically believed (Whitehead
2015), they are nevertheless not rare, and
spaying females prevents these tumours.
Here, I argue that these tumours may be
sufficiently uncommon that it is not clear
that the health and welfare costs associated
with spaying the number of rabbits
needed to prevent a single case of uterine
adenocarcinoma are justified.
Three retrospective studies provide
information on age of occurrence of uterine
adenocarcinomas in pet rabbits. Saito
and others (2002) reported on 47 rabbit
laparotomies for uterine disease over 2.5
years, finding 10 adenocarcinomas and
five adenomas (six cases/year). Walter
and others (2010) reported on 59 rabbits
with uterine disease over seven years, of
which 29 had adenocarcinoma and one
adenoma (4.3 cases/year). Kunzel and
others (2015) found 27 adenocarcinomas
and two adenomas in 50 pet rabbits with
histopathological uterine changes over 6.3
years (4.6 cases/year). The mean age of
the adenocarcinoma/adenoma cases was
5.0, 6.1 and 5.6 years, respectively. Some
of the tumours were incidental findings.
These studies do not indicate the incidence
or prevalence of adenocarcinomas in the
rabbit population, because the size of the
populations the samples came from are
unknown, although 4.3 to six tumours per
year suggests that these tumours are neither
rare nor very common.
Ruelokke and others (2014) examined
33 pet rabbits over 42 months old and
found a 24.4 per cent prevalence of firm
uterine masses, all in rabbits over 60
months, with all three rabbits over 96
months having a palpable uterine mass.
How many rabbits live to be five or
more? In the Netherlands, average lifespan
was 4.2 years (Schepers and others 2009).
Craven and others (2016) reported a median
age at death of rabbits in UK first-opinion
practices in 2013 of four years (interquartile
range: 1.9 to 6.7 years), with 39 per cent
of rabbits living beyond five years. A small
proportion of rabbits – less than five per
cent of those presented to my practice –
live to be 10 or more (Lennox 2010) and
it is possible that rabbits that present to
veterinary practices live longer on average
than those that do not. The proportion of
entire does living long enough to be at high
risk of uterine tumours may be relatively
small.
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.
My future policy is contingent on better
evidence. It took me about five hours to
search our practice management system for
deceased entire does, determine their age at
death and whether there was any evidence
of abdominal tumours in the period leading
up to death. If the RWAF and BVZS could
arrange for perhaps 20 other practices
to do the same, that would constitute
an empirically useful, if scientifically
imperfect, estimate of number-needed-tospay to prevent one case of uterine tumour,
to inform policy regarding whether to
neuter does.
Martin L. Whitehead, Chipping Norton
Veterinary Hospital, Banbury Road,
Chipping Norton, Oxon OX7 5SY
e-mail: martincnvets@gmail.com


== Types of Cancer ==
* '''Uterine adenocarcinoma''': The most widely reported reproductive cancer, typically in does >5 years. 
* '''Mammary tumors''': Hormone-related, occasionally associated with prolactin disturbance. 
* '''Renal neoplasia''': Sometimes appearing as cauliflower-like growths. 
* '''Bone and pituitary tumors''': Less common but noted in case studies. 


== Tumors ==
Gross pathology often shows uterine masses or, in renal cancer, irregular nodular growths resembling cauliflower. Some tumors are incidental findings during necropsy, rather than causes of death.


===Should we advocate neutering for all pet rabbits?===
== Summary Table of Evidence ==
A G Bradbury 1, G J E Dickens 1
{| class="wikitable"
https://pubmed.ncbi.nlm.nih.gov/28008120/
|+ Summary of Spay/Neuter and Cancer Evidence in Rabbits
|-
! Study
! Findings
|-
|1958 colony study
| Reported 80% uterine cancer; based on one genetic herd, not representative.
|-
| Whitehead (2015)
| 10–13% of does >5 years showed masses; NNT (number needed to treat) = 16–20 spays to prevent one case.
|-
| Mäkitaipale et al. (2022)
| 9% adenocarcinoma; most common finding was benign cystic endometrial hyperplasia.
|-
| Walter et al. (2010)
| 29 adenocarcinomas among 59 uterine cases (4.3/year).
|-
| Künzel et al. (2015)
| 27 adenocarcinomas among 50 uterine cases (4.6/year).
|-
| Bertram et al. (2020)
| Broad survey of rabbit neoplasia: multiple tumor types, not limited to uterus.
|}


===Prospective survey of neoplastic and non-neoplastic uterine disorders in 116 domestic rabbits (Oryctolagus cuniculus)===
== Conclusion ==
Author links open overlay panel
Current evidence shows that the risk of uterine adenocarcinoma in intact does is significantly lower than once claimed. While spaying eliminates the risk of uterine cancer, it introduces surgical risks, including a 0.73% perioperative mortality rate for healthy rabbits under anesthesia,<ref>Brodbelt, D.C., et al. "Risk factors for anaesthetic-related death in pet rabbits." ''Veterinary Record'' 162, no. 12 (2008): 388–390.</ref> as well as potential long-term morbidity from adhesions and gastrointestinal stasis. For this reason, veterinary policy remains divided, with some practitioners discouraging routine spaying unless specifically indicated.
Johanna Mäkitaipale a,
Niina Airas b, Sanna Engblom b, Jere Lindén b c
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===
[https://pubmed.ncbi.nlm.nih.gov/33213301/ 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
 
==Types of Cancer==
 
Kidney cancer looks like bumps of cauliflower coming out of the kidney.
 
 
 
 
== Tumors==
 
https://journals.sagepub.com/doi/10.1177/0300985820973460


== References ==
<references />




Revision as of 17:40, 16 August 2025

Cancer in Rabbits

Cancer in rabbits (Oryctolagus cuniculus) has been a subject of veterinary research for decades. Earlier claims suggested extremely high risks of uterine cancer in intact female rabbits, most prominently an oft-cited 1958 colony study reporting rates approaching 80%. However, modern evidence demonstrates that such claims were overgeneralized and based on a limited genetic pool. Contemporary studies show that the actual risk of uterine adenocarcinoma is substantially lower, highly dependent on age and genetics, and must be weighed against the surgical risks of spaying.

Neutering of Pet Rabbits

Veterinary debate continues over whether routine spaying of all female rabbits should be recommended. A 2016 article by Bradbury and Dickens questioned whether universal neutering was in rabbits’ best interest, noting that while spaying prevents uterine adenocarcinoma, it carries welfare and surgical risks.<ref>Bradbury, A.G., and G.J.E. Dickens. "Should we advocate neutering for all pet rabbits?" Veterinary Record 179, no. 24 (2016): 654–655. https://pubmed.ncbi.nlm.nih.gov/28008120/</ref>

In response, some veterinary associations, such as the RWAF and BVZS, defended routine spaying, citing risk reduction. Yet first-opinion practice data, such as those reported by Martin Whitehead (2015), suggest that only 10–13% of does over 5 years old presented with uterine masses, meaning that 16–20 spays would be needed to prevent a single case of uterine cancer.<ref>Whitehead, Martin L. "Letter: Rabbit health." Veterinary Record 180, no. 3 (2017): 77. https://www.tesble.com/10.1136/vr.j826</ref>

Should We Advocate Neutering for All Pet Rabbits?

Bradbury and Dickens emphasized that universal spay policies may not be justified, particularly in single-housed rabbits where social stress and pregnancy risk are absent. They highlighted the need to balance welfare costs, anesthesia risks, and potential benefits.<ref>Bradbury, A.G., and G.J.E. Dickens. "Should we advocate neutering for all pet rabbits?" Veterinary Record 179, no. 24 (2016): 654–655.</ref>

Prospective Studies

Recent prospective and retrospective studies have provided more detailed prevalence data:

  • A 2022 Finnish prospective study (Mäkitaipale et al.) found only 9% adenocarcinoma among 116 rabbits, with the most common finding being cystic endometrial hyperplasia (a benign thickening of the uterine lining common in induced ovulators).<ref>Mäkitaipale, J., N. Airas, S. Engblom, and J. Lindén. "Prospective survey of neoplastic and non-neoplastic uterine disorders in 116 domestic rabbits (Oryctolagus cuniculus)." Veterinary Pathology 59, no. 1 (2022): 78–87. https://doi.org/10.1016/j.jcpa.2022.01.001</ref>
  • Walter et al. (2010) reported 59 cases of uterine disease over 7 years, of which 29 were adenocarcinomas.<ref>Walter, B., et al. "Uterine disorders in pet rabbits: a retrospective study." Journal of Exotic Pet Medicine 19, no. 1 (2010): 18–23.</ref>
  • Künzel et al. (2015) examined 50 cases of uterine disease and found 27 adenocarcinomas.<ref>Künzel, F., et al. "Disorders of the uterus in pet rabbits: a histopathological study." Tierärztliche Praxis 43, no. 1 (2015): 35–40.</ref>

While these reports document uterine neoplasia, incidence rates in the general rabbit population remain unclear because the baseline population size is unknown. Most affected rabbits were 5–7 years old, suggesting that age is a primary risk factor.

Neoplasia and Tumor-Like Lesions

A 2020 retrospective analysis by Bertram et al. of rabbit necropsy cases from 1995 to 2019 reported a variety of neoplasms, including uterine adenocarcinomas but also tumors of the skin, kidneys, and hematopoietic system.<ref>Bertram, C.A., et al. "Neoplasia and tumor-like lesions in pet rabbits (Oryctolagus cuniculus): A retrospective analysis of cases between 1995 and 2019." Veterinary Pathology 58, no. 6 (2020): 1032–1042. https://doi.org/10.1177/0300985820973460</ref>

Types of Cancer

  • Uterine adenocarcinoma: The most widely reported reproductive cancer, typically in does >5 years.
  • Mammary tumors: Hormone-related, occasionally associated with prolactin disturbance.
  • Renal neoplasia: Sometimes appearing as cauliflower-like growths.
  • Bone and pituitary tumors: Less common but noted in case studies.

Tumors

Gross pathology often shows uterine masses or, in renal cancer, irregular nodular growths resembling cauliflower. Some tumors are incidental findings during necropsy, rather than causes of death.

Summary Table of Evidence

Summary of Spay/Neuter and Cancer Evidence in Rabbits
Study Findings
1958 colony study Reported 80% uterine cancer; based on one genetic herd, not representative.
Whitehead (2015) 10–13% of does >5 years showed masses; NNT (number needed to treat) = 16–20 spays to prevent one case.
Mäkitaipale et al. (2022) 9% adenocarcinoma; most common finding was benign cystic endometrial hyperplasia.
Walter et al. (2010) 29 adenocarcinomas among 59 uterine cases (4.3/year).
Künzel et al. (2015) 27 adenocarcinomas among 50 uterine cases (4.6/year).
Bertram et al. (2020) Broad survey of rabbit neoplasia: multiple tumor types, not limited to uterus.

Conclusion

Current evidence shows that the risk of uterine adenocarcinoma in intact does is significantly lower than once claimed. While spaying eliminates the risk of uterine cancer, it introduces surgical risks, including a 0.73% perioperative mortality rate for healthy rabbits under anesthesia,<ref>Brodbelt, D.C., et al. "Risk factors for anaesthetic-related death in pet rabbits." Veterinary Record 162, no. 12 (2008): 388–390.</ref> as well as potential long-term morbidity from adhesions and gastrointestinal stasis. For this reason, veterinary policy remains divided, with some practitioners discouraging routine spaying unless specifically indicated.

References

<references />


Summary Table of Evidence

Summary of Evidence on Spay/Neuter Risks in Rabbits
Theme Key Insight
Immune Dysfunction Neutering reduces cancer-resisting T-cells, potentially increasing tumor risk.
Hormonal Cancer Pathways Prolactin and hormone disturbances may contribute to mammary tumor development.
Broader Health Impacts Gonad removal is linked to bone, endocrine, obesity, and other systemic issues.
Surgical Risks High perioperative mortality due to anesthesia complications and GI issues.
Sterility Mechanisms Hormone and germ cell changes post-sterilization may promote tumorigenesis in models.
Retrieved from "https://mmcrabbits.com/BCWiki/index.php?title=Cancer&oldid=46575"