KNOWLEDGE SUMMARY
Keywords: ANAEMIA; ANAESTHESIA; LIVER LOBE TORSION; MEDICAL; RABBIT; SURGERY
Comparison of medical versus surgical management of liver lobe torsion in rabbits.
Rachel Sibbald, RVN1*
1 Abercorn Vets, United Kingdom
* Corresponding author email: rachel.sibbald@abercornvets.co.uk
Vol 9, Issue 3 (2024)
Submitted: 30 Jul 2023; published: 19 Jul 2024; next review: 01 Mar 2026
DOI: https://doi.org/10.18849/ve.v9i3.687
PICO question
Does medical management of liver lobe torsion in rabbits reduce mortality compared with surgical intervention?
Clinical bottom line
Category of research
Treatment.
Number and type of study designs reviewed
Six studies were appraised in total. This consisted of three retrospective cohort studies and three case series.
Strength of evidence
Weak.
Outcomes reported
Medical management carries a similar 7-day survival rate compared to surgical treatment; however, long-term morbidity and mortality is increased compared with surgery. Delayed diagnosis and severe anaemia negatively affect outcomes of both groups.
Conclusion
Medical management does not reduce mortality compared with surgical treatment and within the literature there appears to be a preference for surgery when treating rabbits with liver lobe torsion.
How to apply this evidence in practice
The application of evidence into practice should take into account multiple factors, not limited to: individual clinical expertise, patient’s circumstances and owners’ values, country, location or clinic where you work, the individual case in front of you, the availability of therapies and resources.
Knowledge Summaries are a resource to help reinforce or inform decision making. They do not override the responsibility or judgement of the practitioner to do what is best for the animal in their care.
Clinical scenario
You are presented with a lethargic, anorexic rabbit which arrived as an emergency case after the owner noticed a sudden change in demeanour. On the clinical exam you notice the mucous membranes are pale and the cranial abdomen is firm and painful. Blood analysis reveals severe anaemia with raised liver enzymes. Ultrasonography confirms the suspicion of a liver lobe torsion with no doppler colour blood flow identified in a swollen lobe of liver surrounded by a small volume of free fluid. The owner wishes to pursue treatment but is very concerned about the risk of anaesthesia and surgery and wants to know if this can be avoided. An alternative consideration is medical management.
The evidence
All of the studies identified are retrospective in nature and include cohorts and case series. Case series (Leonard et al., 2022; Stanke et al., 2011; Wenger et al., 2009) represent the weakest evidence available in this Knowledge Summary, as there is often an absence of data on potential confounding factors and there can be a range of bias that stem from issues such as loss to follow up or recall bias. In this Knowledge Summary, only descriptions of surgical treatment are reported and no evidence of case series surrounding medical management for comparison were found. This could represent a failure to diagnose the condition without exploratory surgery or bias in reporting surgical cases. Collectively the studies provide valuable information to aid clinicians with treatment of this rare condition, given the reported relative success of surgical intervention.
The cohort studies (Graham et al., 2014; Ozawa et al., 2022; Sheen et al., 2022) provide comparative data of medical and surgical treatment, allowing a more balanced evaluation in relation to the PICO question and a moderate strength of evidence when the limitations of studying this type of condition are considered. Both larger cohort studies (Ozawa et al., 2022; Sheen et al., 2022) found that the 7-day survival rate did not differ significantly between the medical and surgical groups, indicating medical management does not reduce mortality compared with surgery.
Summary of the evidence
Graham et al. (2014)
Population: |
Rabbits diagnosed with liver lobe torsion at Angell Animal Medical Centre (Boston, USA) between January 2007 and March 2012. |
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Sample size: |
16 Rabbits. |
Intervention details: |
9 rabbits underwent exploratory surgery and liver lobectomy:
7 rabbits received supportive medical treatment only:
|
Study design: |
Retrospective single centre cohort study. |
Outcome studied: |
Mortality rate of surgical and medical management. |
Main findings |
|
Limitations: |
|
Leonard et al. (2022)
Population: |
Rabbits diagnosed with a caudate liver lobe torsion at University of Wisconsin Veterinary Care (USA) between January 2018 and October 2021. |
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Sample size: |
22 rabbits. |
Intervention details: |
22 rabbits underwent exploratory surgery and liver lobectomy:
|
Study design: |
Retrospective single centre case series. |
Outcome studied: |
|
Main findings |
|
Limitations: |
|
Ozawa et al. (2022)
Population: |
Rabbits with liver lobe torsion at 4 veterinary referral hospitals (unknown, USA) between 1 January 2010 and 31 July 2020. |
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Sample size: |
82 rabbits. |
Intervention details: |
9/82 (11%) rabbits were euthanised or died on presentation. 50/82 rabbits underwent surgical liver lobectomy:
23/82 rabbits received medical treatment only, however supportive care was provided to surgical rabbits too which included:
|
Study design: |
Retrospective multi-centre cohort study. |
Outcome studied: |
|
Main findings |
|
Limitations: |
|
Sheen et al. (2022)
Population: |
Rabbits with liver lobe torsion torsion at Sydney Exotics and Rabbit Vets, Australia studied between 2016 and 2021. |
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Sample size: |
40 rabbits. |
Intervention details: |
15/40 (37.5%) of rabbits were treated medically, this included:
23/40 (57.5%) of rabbits were treated surgically in addition to the medical therapy described above. This included:
|
Study design: |
Retrospective single centre cohort study. |
Outcome studied: |
Subjective outcomes measured included return to ‘normal’ defaecation and food intake. Objective outcomes included improvement of PCV and biochemical parameters and survival 4 weeks after diagnosis. |
Main findings |
|
Limitations: |
|
Stanke et al. (2021)
Population: |
Rabbits with liver lobe torsion evaluated at Angell Animal Medical Centre (Boston, USA) between June 2007 and March 2009. |
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Sample size: |
4 rabbits. |
Intervention details: |
Case 1 - Exploratory laparotomy
Case 2 – Exploratory laparotomy
Case 3 – Exploratory laparotomy
Case 4 – Exploratory laparotomy
|
Study design: |
Retrospective case series. |
Outcome studied: |
Surgical success (subjectively measured by wellness postoperatively, objectively measured by documentation of survival). |
Main findings |
|
Limitations: |
|
Wenger et al. (2009)
Population: |
Rabbits with liver lobe torsion. |
---|---|
Sample size: |
3 rabbits. |
Intervention details: |
Case 1 (5 kg) – Surgical case although initially managed medically for 24 hours:
Case 2 (2.2 kg) – Medical management:
Case 3 (2.6 kg) – Medical management resulting in euthanasia (owner declined exploratory laparotomy):
|
Study design: |
Retrospective case series. |
Outcome studied: |
|
Main findings |
|
Limitations: |
|
Appraisal, application and reflection
Liver lobe torsion (LLT) is a rare condition described in many species including humans, dogs, pigs, rats, and rabbits (Graham and Basseches, 2014). The aetiology is unknown but predisposing factors in humans and dogs are thought to include congenital absence of hepatic ligaments, dilation of abdominal organs, and surgical or external trauma to the abdomen (Graham and Basseches, 2014). Acute venous infarction, thrombus formation, and hepatic necrosis can result in the development of effusion of the abdomen and thorax, haemoabdomen, and ultimately, acute death. Disseminated intravascular coagulation has been reported as a complication of bacterial toxin and ischaemic by-product release. In dogs, the left lobe is most affected; however, in rabbits the caudate lobe located in the right cranial abdomen is more commonly involved (Oglesbee and Lord, 2020). This is thought to be because of the narrow attachment to the dorsal hilar region of the liver (Summa and Brandão, 2017). This would suggest when applying this knowledge to clinical practice that further investigation is warranted when abdominal pain or mass effect is palpated in the right cranial abdomen of rabbits.
Clinical signs are non-specific and can mimic other disorders causing pain. The largest cohort study (Ozawa et al., 2022) found that the most common presenting complaint was reduced appetite or anorexia (76/82 (92.7%)), followed by lethargy (46/82 (56%)) and decreased defaecation (38/82 (46.3%)) of rabbits. In clinical practice, this is a very common presentation and highlights the need for thorough clinical examination and investigation into what are vague and non-pathognomonic symptoms. Clinical examination may reveal abdominal pain, dehydration, dull mentation, pale mucous membranes, and decreased borborygmi (Graham and Basseches, 2014).
Diagnosis is achieved through a combination of evaluation of clinical signs, blood testing and diagnostic imaging. Sheen et al. (2022) found that anaemia and elevated plasma alanine aminotransferase and blood urea nitrogen were common clinicopathologic results. This correlates to the findings by Ozawa et al., (2022) where 47/82 (59.5%) of rabbits were anaemic. Ozawa et al., (2022) also reports that rabbits with moderate or severe anaemia were significantly less likely to survive for seven days (P = 0.006; OR, 4.41; 95% CI, 1.55–12.51) than rabbits with mild or no anaemia. In the study by Sheen et al., (2022) an identified limitation was a potential confounding factor within the surgical group. These rabbits were administered a blood transfusion from a healthy donor if the packed cell volume (PCV) was less than 20%, whereas the medical group was not offered this intervention. Of these rabbits, 6/7 (85%) survived, whilst non-survivors of the medical group all had a PCV of less than 20%. When evaluating the studies collectively, the use of blood transfusion was surprisingly uncommon (or not described) despite descriptions of rabbits demonstrating criteria that would normally necessitate transfusion. This includes a PCV of less than 20%, blood loss associated with collapse, ongoing haemorrhage or poor response to conventional shock therapy with crystalloid or colloid fluids (Lichtenberger, 2004). Identification of criteria for blood transfusion, using objective parameters such as a PCV, may help shape recommended treatment interventions in future studies of LLT. Diagnostic modality appeared to vary between institutions and within institutions for different cases. The large cohort study by Ozawa et al., (2022) used ultrasonography to diagnose all 82 cases whereas Sheen et al., (2022) and Leonard et al., (2022) relied on a combination of ultrasound and computed tomography (CT). In practice this may be limited by availability of equipment and user competency and anecdotally, ultrasonographic diagnosis may be hindered by gastrointestinal gas and fast respiratory motion artefact. A study by Specchi and d’Anjou (2019) concluded that either ultrasound or CT can be used independently to diagnose vascular disease including organ torsion in small animals but given the complexity of vascular anatomy their combined use likely yields higher diagnostic accuracy.
A common theme throughout the evaluation was lack of information surrounding the rationale for either surgical or medical management. This information is invaluable for clinicians in practice where lack of experience may hinder decision making. Trends of data would have been useful in the cohort studies to assess whether there were clinical parameters which influenced treatment modality. Equally, factors outside the animals’ clinical condition may have influenced treatment (such as owner consent), therefore, documentation of this would have been useful where available. None of the case reports or series included documentation of medical management, which could represent publication bias towards cases of positive surgical intervention. On balance, there is a strong recommendation in other species that surgical resection is necessary to avoid the effects of venous obstruction, such as thrombosis and necrosis (Swann and Brown, 2001). Despite the lack of comparison in relation to the PICO question the surgical case reports do provide value, as knowledge and experience can be transferred to readers and detail of anaesthesia protocols in critically ill rabbits may help clinicians in practice.
The studies which did involve medical management cases for comparison (Graham et al., 2014; Ozawa et al., 2022; Sheen et al., 2022; Wenger et al., 2009) varied somewhat in strategy; however, the principles (which are applicable to many conditions in rabbits) were essentially the same. Fluid therapy was delivered either intravenously or subcutaneously, a range of gastrointestinal prokinetics were used, opioids and non-steroidal anti-inflammatories were used as analgesia, and antibiotic use was common. Retrospective studies can lack control for chance, bias, and confounders, and as the interventions differed between patients, data shared was reliant upon accurate record keeping and reporting. In the Graham et al. (2014) study, two rabbits within the medical treatment group that died, had delayed diagnosis and concurrent illness but were still included in the outcome analysis. One of these rabbits had severe co-morbidities and therefore, data interpretation in this study should be approached with caution due to the small sample size (16 rabbits) and the inclusion of these animals. Sheen et al. (2022) categorised a rabbit in both the medical and surgical group despite it ultimately receiving surgery and surviving and in the same study two rabbits in the medical group had a delay in diagnosis. The same study showed no significant outcome difference between medical and surgical management. The authors suggest that prompt diagnosis within one day of presentation and evidence of relatively modest blood loss appeared to support successful medical management. Ozawa et al. (2022) also found patients that underwent surgery did not have a significantly different 7-day outcome, but median survival time was 530 days for rabbits that received only medical treatment and was 1452 days for rabbits that underwent surgery.
Therefore, despite the limitations identified within the retrospective studies examined (Graham et al., 2014; Ozawa et al., 2022; Sheen et al., 2022; Wenger et al., 2009), they do have significant value that allows clinicians to consider both medical and surgical options in the rabbit. Clinically, there is broad similarity between all the studies and the techniques used for medical support and this should provide a good starting point for supporting rabbit patients. However, further work is needed to evaluate the role blood transfusion has to play in improving patient outcomes in this condition, anaesthesia of surgical patients and a review of the methodology clinicians use when deciding whether to approach medical or surgical treatment would be beneficial.
Only one of the studies (Leonard et al., 2022) described a difference in surgical approach and made direct comparison of two techniques. The study described prior use of cadavers to assess feasibility of a paracostal approach to access the liver versus the more familiar ventral midline approach. Interestingly, the mortality rate of rabbits that underwent surgery via the paracostal approach was 0% compared to the 5/13 (38.5%) seen in the ventral midline group. The authors of this study proposed this may be because of the position of the rabbit during surgery. Anecdotally, more anaesthetic challenges are seen when rabbits are positioned in dorsal recumbency due to the gastrointestinal tract placing pressure on the vena cava resulting in trouble managing patient blood pressure and secondly a full stomach may impede respiratory movements if there is pressure on the diaphragm (Heskin, 2019). A third consideration is access during surgery and the authors found that there was improved exposure of the caudate lobes vascular pedicle when using the paracostal approach. This may explain the higher incidence of intra-operative haemorrhage in the ventral midline group due to obstructed access/vision. Further studies are required using larger case numbers to assess viability and practicality of the paracostal approach to determine whether this approach should be used preferentially to the midline approach if surgery is undertaken.
Methodology
Search strategy
Databases searched and dates covered: |
CAB Abstracts on Ovid Platform from 1973 to 1 March 2024 |
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Search strategy: |
CAB Abstracts (Pet rabbit* OR domestic rabbit* OR rabbit OR rabbits OR Oryctolagus cuniculus) AND (liver lobe) PubMed (Pet rabbit* OR domestic rabbit* OR rabbit OR rabbits OR Oryctolagus cuniculus) AND (liver lobe torsion) |
Dates searches performed: |
01 Mar 2024 |
Exclusion / inclusion criteria
Exclusion: |
|
---|---|
Inclusion: |
Relevant to PICO question, peer-reviewed and available in English. |
Search outcome
Database |
Number of results |
Excluded – Not relevant to PICO |
Excluded – Cadaveric study |
Excluded – Not available in English |
Excluded – Not available online |
Excluded – Review article |
Excluded – Single case study |
Total relevant papers |
---|---|---|---|---|---|---|---|---|
CAB Abstracts |
25 |
10 |
1 |
1 |
1 |
2 |
4 |
6 |
PubMed |
16 |
5 |
2 |
0 |
1 |
4 |
0 |
4 |
Total relevant papers when duplicates removed |
6 |
ORCiD
Rachel Sibbald: https://orcid.org/0000-0003-1741-2434
Conflict of interest
The author declares no conflicts of interest.
References
- Graham, J.E. and Basseches, J. (2014). Liver Lobe Torsion in Pet Rabbits: Clinical Consequences, Diagnosis, and Treatment. Veterinary Clinics of North America: Exotic Animal Practice. 17(2), 195–202. DOI: https://doi.org/10.1016/j.cvex.2014.01.004
- Graham, J. E., Orcutt, C.J., Casale, S.A. & Basseches, J. (2014). Liver Lobe Torsion in Rabbits: 16 Cases (2007 to 2012)’ Journal of Exotic Pet Medicine. 23(3), 258–265. DOI: https://doi.org/10.1053/j.jepm.2014.06.010
- Heskin, K. (2019). Rabbit Anaesthesia - Understanding Your Patient. [Online]. Alfaxan Multidose. Last Updated: 19 April 2019. Available at: https://alfaxan.co.uk/news/rabbit-anaesthesia-understanding-your-patient [Accessed 15 June 2024].
- Leonard, K.C., Zhao, Q, Taber, R.H., & Colopy, S. (2022). Paracostal versus ventral midline approach for caudate liver lobectomy in the rabbit. Veterinary Surgery. 51(6), 920–928. DOI: https://doi.org/10.1111/vsu.13838
- Lichtenberger, M. (2004). Transfusion medicine in exotic pets. Clinical Techniques in Small Animal Practice. 19(2), 88–95. DOI: https://doi.org/10.1053/j.ctsap.2004.01.006
- Oglesbee, B. L., & Lord, B. (2020). Gastrointestinal Diseases of Rabbits. Ferrets, Rabbits, and Rodents, 174–187. https://doi.org/10.1016/B978-0-323-48435-0.00014-9
- Ozawa, S.M., Graham, J.E., Guzman, D.S., Tucker, S.M., Petritz, O.A., Sullivan, P., Robertson, J.B. & Hawkins, M.G. (2022). Clinicopathological findings in and prognostic factors for domestic rabbits with liver lobe torsion: 82 cases (2010–2020). Journal of the American Veterinary Medical Association. 260(11), 1334–1342 DOI: https://doi.org/10.2460/javma.22.03.0154
- Sheen, J.C., Vella, D., & Hung, L. (2022). Retrospective analysis of liver lobe torsion in pet rabbits: 40 cases (2016-2021). Veterinary Record, 191(7), e1971. DOI: https://doi.org/10.1002/vetr.1971
- Specchi, S., and d'Anjou, M. (2019). Diagnostic imaging for the assessment of acquired abdominal vascular diseases in small animals: A pictorial review. Veterinary Radiology and Ultrasound. 60(6), 613–632. DOI: https://doi.org/10.1111/vru.12780
- Stanke, N. J., Graham, J. E., Orcutt, C. J., Reese, C. J., Bretz, B. K., Ewing, P. J., & Basseches, J. (2011). Successful outcome of hepatectomy as treatment for liver lobe torsion in four domestic rabbits. Journal of the American Veterinary Medical Association. 238(9), 1176–1183. DOI: https://doi.org/10.2460/javma.238.9.1176
- Summa, N.M., & Brandão, J. (2017). Evidence-Based Advances in Rabbit Medicine. Veterinary Clinics of North America: Exotic Animal Practice. 20(3), 749–771. DOI: https://doi.org/10.1016/j.cvex.2017.04.008
- Swann, H. M., & Brown, D. C. (2001). Hepatic lobe torsion in 3 dogs and a cat. Veterinary Surgery. 30(5), 482–486. DOI: https://doi.org/10.1053/jvet.2001.25877
- Wenger, S., Barrett, E.L., Pearson, G. R., Sayers, I., Blakey, C., & Redrobe, S. (2009). Liver lobe torsion in three adult rabbits. Journal of Small Animal Practice. 50(6), pp. 301–305. DOI: https://onlinelibrary.wiley.com/doi/10.1111/j.1748-5827.2008.00719.x
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