Comparison of medical versus surgical management of liver lobe torsion in rabbits.

Rachel Sibbald, RVN^1*

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

16 Rabbits.

• 14/16 rabbits had a complete blood count performed.
• 12/16 had abdominal radiographs.
• 14/16 had abdominal ultrasonography performed which was diagnostic in all cases.

9 rabbits underwent exploratory surgery and liver lobectomy:

• Surgical correction involved circumferential ligature occlusion of the lobe/s and transection distal to the ligatures.
• Histologic examination was performed in all cases and was consistent with liver lobe torsion.

7 rabbits received supportive medical treatment only:

• Supportive care included administration of subcutaneous fluids, analgesia, antibiotics, supplemental feeding and prokinetic agents.

Retrospective single centre cohort study.

• 9/9 rabbits treated surgically survived.
• 3/7 rabbits treated medically survived.
• All 12/16 rabbits that survived to discharge are reported to have had no recurrent episodes of liver lobe torsion.
• 3/7 rabbits that survived and were treated medically reportedly had multiple episodes of recurrent gastrointestinal stasis that responded to medical management.
• The median hospital stay for medically treated rabbits was 2 days
• The median hospital stay for surgically treated rabbits was 4 days.

• 2 rabbits within the medical treatment group that died had delayed diagnosis and concurrent illness but were still included in the outcome analysis.
• The first rabbit was not diagnosed until post-mortem. This animal also had toxic blood lead levels and decompensated despite chelation therapy.  Necropsy confirmed a concurrent liver lobe torsion. 
• The second rabbit was initially treated on an emergency basis however no diagnostic testing was performed until 2 days later. Surgical treatment was recommended but the rabbit died before surgery.  Delay in diagnosis could have contributed towards the lower success rate in the medical treatment group
• It is unclear if the medical management regime was standardised within the medical group whilst the surgical technique appears relatively consistent.
• Details of medical treatment are lacking (i.e. specific drugs and dosages’).
• The paper does not detail the haematological and biochemical parameters of animals pertinent to their intervention group.
• General anaesthesia details from the surgical group are lacking.
• It is unclear if every case was offered equal opportunity for both medical or surgical treatment or what criteria was used to determine suitability for each treatment.
• As this is a retrospective, descriptive study, there is no control for chance, bias, and confounders.

22 rabbits.

• 21/22 rabbits had a biochemistry panel alongside measurement of packed cell volume and total solids.
• 6/22 were diagnosed via ultrasonography.
• 14/22 were diagnosed via abdominal computed tomography (CT).
• 2/22 were diagnosed via abdominal CT combined with ultrasonography.

22 rabbits underwent exploratory surgery and liver lobectomy:

• Surgical correction was performed using 2 techniques (13/22 via a ventral midline approach and 9/22 via a paracostal approach).

Retrospective single centre case series.

• Mortality rate of each surgical approach.
• Time to eating.
• Anaesthesia/surgical time.

• The mortality rate in the ventral midline surgical cases was 5/13 (38.5%).
• The mortality rate in the paracostal surgical cases was 0/9 (0%).
• Overall survival of both groups was 17/22 (77.2%).
• There was no statistical difference in anaesthetic or surgical time between the 2 groups.
• The median hospital stay for treated rabbits was 2 days.in both groups.

• It is not clear how long it was between diagnosis and surgical intervention for each rabbit.
• There was lack of control for anesthesia protocols, attending surgeon and anesthetist.
• It is not clear if rabbits had medical stabilisation performed prior to surgery and whether this was standardised between rabbits.
• General anaesthesia details are lacking as well as whether the anaesthetist was consistent in both groups.
• It is unclear what criteria was used to determine suitability for each surgical approach beyond surgeon preference and the study identified that this was because there was a reluctance to try a new surgical technique.
• As this is a retrospective, descriptive study, there is no control for chance, bias, and confounders.
• There are no medical cases for comparison in relation to the PICO question.
• It does not appear histopathology was performed in any surgical cases to confirm the diagnosis.
• Some rabbits received a blood transfusion but details surrounding indications for this are lacking.

82 rabbits.

9/82 (11%) rabbits were euthanised or died on presentation.

50/82 rabbits underwent surgical liver lobectomy:

• Surgical technique was described in 44 rabbits – suture ligation (26), instrument ligation (15), surgical looping device (2) and a vessel sealing device (1).
• Surgical complications included haemorrhage and incomplete resection.

23/82 rabbits received medical treatment only, however supportive care was provided to surgical rabbits too which included:

• Crystalloid fluid therapy with 1 rabbit also receiving hypertonic saline.
• Antibiotics were prescribed in 61/82 (74.4%) of rabbits.
• 67/82 (81.7%) rabbits received opioid analgesia including buprenorphine or a full mu agonist.
• 9/82 (11%) received a blood transfusion.

Retrospective multi-centre cohort study.

• Clinicopathological findings in rabbits with liver lobe torsions.
• Prognostic indicators.
• Mortality rate of surgical and medical management.

• 36/50 (72%) of rabbits that underwent surgical intervention survived at least 7 days.
• 14/23 (60.9%) of medically treated rabbits survived at least 7 days.
• Overall, 32/82 (39%) rabbits died within 7 days of presentation and 50/82 (61%) survived.
• The 7-day survival rate did not differ significantly between the medical and surgical groups.
• The peri-anaesthetic mortality rate was 9/50 (17%).
• Median survival time following medical management was 530 days versus 1452 days with surgical treatment.
• Rabbits with caudate torsions were more likely to survive >7 days than those with right liver lobe torsions.
• A higher heart rate (HR) was associated with a worse outcome (P = 0.013; HR for each 10-beats/min increase in HR, 1.1; 95% CI, 1.02 to 1.19).
• For each additional day without defaecating, rabbits had a significantly lower survival time (P < 0.001; HR, 1.77; 95% CI, 1.3 to 2.41).
• Rabbits that received tramadol had longer survival time, compared with those that did not (P  = 0.018; HR, 0.2; 95% CI, 0.06 to 0.7).

• The distribution of cases amongst the 4 hospitals has not been analysed and therefore is a source of potential bias if variation in treatment strategy and assessment/interpretation of results exists.
• 29/82 (35.4%) of rabbits were referred from another vet. This may create bias towards more severely affected rabbits being documented in the study.
• Statistical analysis of the biochemical and haematological parameters pertaining to each group would have been useful to identify any trends in data.
• The distribution of referral cases to each group has not been described.
• It is unclear if every case was offered equal opportunity for both medical or surgical treatment or what criteria was used to determine suitability for each treatment.
• There is no information surrounding concurrent co-morbidities which may have affected outcome in both groups.
• As this is a descriptive study, that is retrospect in nature, there was no control for chance, bias and confounders.

Rabbits with liver lobe torsion torsion at Sydney Exotics and Rabbit Vets, Australia studied between 2016 and 2021.

40 rabbits.

• Packed cell volume and plasma biochemical testing was performed in 39/40 rabbits.
• Diagnostic imaging was performed in 38/40 rabbits.

15/40 (37.5%) of rabbits were treated medically, this included:

• Active warming if hypothermic.
• Opioid analgesia (buprenorphine 0.03 mg/kg subcutaneously (SC) or intravenously (IV) Q8h or 2 μg/kg/h fentanyl constant rate infusion).
• A dose range of 2–5 mg/kg ranitidine per os (PO) or IV Q12h or cisapride 0.5 mg/kg PO Q12h.
• Supplemental feeding with a herbivorous diet.
• Antibiotics were used to prevent bacterial translocation and included the use of procaine penicillin 30mg/kg Q24h SC and 20 mg/kg metronidazole Q12h (PO) or 7.5 mg/kg metronidazole Q12h IV. Antibiosis was continued for 2 weeks.

23/40 (57.5%) of rabbits were treated surgically in addition to the medical therapy described above.  This included:

• General anaesthesia and surgical resection of the affected lobe.
• Ligation and occlusion of the vascular pedicle was performed using metal ligation clips, an electrosurgery bipolar vessel sealing system, surgical stapling devices, or distal transection.
• Rabbits with a packed cell volume (PCV) of less than 20%. (7/23) in the surgical group received a whole blood transfusion from a healthy donor.

Retrospective single centre cohort study.

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.

• Overall, 30/40 (75%) of rabbits survived
• 15/15 (100%) of medically treated rabbits presented with reduced appetite. Of these, 12/15 (80%) survived
• 23/23 (100%) of rabbits that underwent surgery presented with reduced appetite. 19/23 (82.6%) of these rabbits   
• Surgical intervention did not confer a significant difference in outcome compared to medical management (odds ratio 0.77, 95% confidence interval 0.15–10, P = 0.761).
• The peri-anaesthetic mortality rate was 4/23 (17.4%).
• For each percentage drop in PCV, the odds of a poor outcome increased by 12%.
• For each single unit increase (mmol/L) of urea, the odds of a poor outcome increased by 13%.

• Although a common inherent limitation of a retrospective case series is a lack of record keeping standardisation, it is unclear if every case was offered equal opportunity for both medical or surgical treatment or what criteria was used to determine suitability for each treatment.
• It is unclear why only the rabbits in the surgical group were offered a blood transfusion peri-operatively if PCV was less than 20%. This intervention is a potential confounding factor as this could have directly affected outcome/chance of survival.
• It is unclear if all animals were first opinion or referred from other vets (this could possibly result in bias towards more severely affected rabbits).
• 1 rabbit was grouped in both the surgical and medical group and included in statistical analysis despite ultimately receiving surgical treatment and surviving.
• 2 rabbits in the medical group had a delay in diagnosis. One rabbit was only diagnosed shortly before euthanasia and 1 on post-mortem examination.  Both rabbits had a PCV < 20%.
• Imaging used for diagnosis was not standardised, with some rabbits undergoing CT scanning and some rabbits ultrasonographic diagnosis.
• There is no information surrounding concurrent co-morbidities or long-term medications which may have affected outcome in both groups.
• As this is a descriptive study that is retrospect in nature, there is no control for chance, bias, and confounders.

Rabbits with liver lobe torsion evaluated at Angell Animal Medical Centre (Boston, USA) between June 2007 and March 2009.

4 rabbits.

Case 1 - Exploratory laparotomy

• The rabbit was treated medically for 24 hours prior to surgery and was administered Lactated Ringer's Solution (4 ml/kg), intravenously (IV), Q1h and then 33 ml/kg (15 ml), subcutaneously (SC), Q8h), buprenorphine (0.04 mg/kg, SC, Q8h), enrofloxacin (10 mg/kg, per os (PO), Q12h), and metronidazole (20 mg/kg, PO, Q12h). Alongside syringe feeding with a herbivorous liquid diet (15 ml/kg, PO, Q8h).
• Premedication for surgery was achieved with buprenorphine 0.04 mg/kg and midazolam 0.5 mg/kg intramuscularly (IM) alongside meloxicam 0.4 mg/kg SC.
• Isoflurane with oxygen was delivered by an anaesthetic chamber followed by mask induction until the rabbit’s anaesthetic plane allowed endotracheal intubation.
• The affected liver lobe was occluded at the hilus with 2 circumferential ligatures of 2-0 polydioxanone suture and removed via transection distal to the ligatures.
• The medical treatment regimen was continued post-operatively and administration of metoclopramide hydrochloride (0.5 mg/kg, PO, Q8h) was commenced 2 days
  following surgery to increase gastrointestinal motility.

Case 2 – Exploratory laparotomy

• The rabbit was treated medically for 24 hours prior to surgery and received Lactated Ringer's Solution (33 ml/kg, SC, Q8h), buprenorphine (0.04 mg/kg, SC, Q8h), and syringe feeding (15 ml/kg, PO, Q8h).
• The rabbit was premedicated with midazolam (0.7 mg/kg, IV) and butorphanol (0.2 mg/kg, IV).
• Anaesthesia was induced with isoflurane and oxygen in an anaesthetic chamber followed by mask induction until the rabbit’s anaesthetic plane allowed endotracheal intubation.
• Two circumferential ligatures of 3-0 polydioxanone suture were placed around the hilus of the torsed liver lobe, which was removed via transection distal to the ligatures.
• Following surgery, the rabbit was administered Lactated Ringer's Solution (4 ml/kg, IV, Q1h and then 33 ml/kg, SC, Q8h), buprenorphine (0.04 mg/kg, SC, Q8h), enrofloxacin
  (10 mg/kg, PO, Q12h), metoclopramide (0.5 mg/kg, PO, Q8h), and meloxicam (0.3 mg/kg, PO, Q12h). Alongside syringe feeding with a herbivorous liquid diet (15 ml/kg, PO, Q8h).

Case 3 – Exploratory laparotomy

• The rabbit was admitted to the hospital and given Lactated Ringer's Solution (4 ml/kg, IV, Q1h) with concurrent heat support overnight.
• 24 hours later, the rabbit was premedicated with midazolam (0.3 mg/kg, IM), buprenorphine (0.04 mg/kg, IM), and glycopyrrolate (0.02 mg/kg, SC). Anaesthesia was induced with isoflurane and oxygen delivered by an anaesthetic chamber followed by mask induction until the rabbit’s anaesthetic plane allowed endotracheal intubation.
• Three circumferential ligatures of 3-0 polypropylene suture were placed around the hilus of the torsed caudate lobe, and 2 stainless steel ligation clips were placed distal to the ligatures and the lobe was transected between the clips.
• Following surgery, the rabbit was administered Lactated Ringer's Solution (4 ml/kg, IV, Q1h and then 33 ml/kg, SC, Q8h), buprenorphine (0.04 mg/kg, SC, Q8h), enrofloxacin (10 mg/kg, PO, Q12h), metronidazole (20 mg/kg, PO, Q12h), meloxicam (0.3 mg/kg, PO, Q12h) and cisapride (0.5 mg/kg, PO, Q8h), and syringe feeding (15 ml/kg, PO, Q8h).

Case 4 – Exploratory laparotomy

• The rabbit was admitted to the hospital and administered Lactated Ringer's Solution (4 ml/kg, IV, Q1h and then 33 ml/kg, SC, Q8h), buprenorphine (0.04 mg/kg, SC, Q8h), enrofloxacin (10 mg/kg, PO, Q12h), metoclopramide (0.5 mg/kg, PO, Q8h), and meloxicam (0.3 mg/kg, PO, Q12h) and syringe feeding (15 ml/kg, PO, Q8h).
• The rabbit was premedicated with midazolam (0.5 mg/kg, SC), buprenorphine (0.04 mg/kg, SC), and glycopyrrolate (0.02 mg/kg, SC). Anaesthesia was induced with isoflurane and oxygen delivered by an anaesthetic chamber followed by mask induction until the rabbit’s anaesthetic plane allowed endotracheal.
• Three circumferential sutures of 3-0 nylon suture were placed around the hilus of the torsed caudate lobe, which was removed via transection distal to the sutures.

Retrospective case series.

• All 4 rabbits survived surgery.
• Case 1 was still alive at 43 months post-surgery, case 2 was alive at 41 months post-surgery, case 3 was alive at 25 months post-surgery, and case 4 was alive 22 months after surgery.
• The mainstay of medical support to surgery included the administration of buprenorphine, meloxicam, lactated ringers solution (LRS), syringe feeding, antibiosis, and gastrointestinal prokinetics.

• There were no medically treated rabbits for comparison.
• The sample size is small and there is no quantitative/statistical data.
• As this is a descriptive study, that is retrospect in nature, there was no control for chance, bias, and confounders.
• Details of inclusion criteria are missing, there is therefore a risk of selection bias in this report.

3 rabbits.

• Haematology was analysed for cases 1 and 2, and mean packed cell volume (PCV) was 16.6%.
• Biochemical parameters showed marked increases in liver enzymes (alanine transaminase and aspartate aminotransferase) in all 3 rabbits.

Case 1 (5 kg) – Surgical case although initially managed medically for 24 hours:

• Hartmann's solution was delivered at 30 ml/hr intravenously.
• 10 ml/kg oral electrolyte solution.
• 0.4 mg/kg buprenorphine intravenously (IV).
• 2 mg/kg meloxicam once daily subcutaneously.
• 5 mg/kg ranitidine per os (PO) twice daily (BID).
• Fine needle aspiration of the liver revealed normal cytology.
• The rabbit was premedicated with 0.06 mg/kg of fentanyl and 2 mg/kg of fluanisone intramuscularly (IM), followed by 8 mg/kg propofol and  3 mg/kg of midazolam intravenously. Anaesthesia was maintained with isoflurane in oxygen via an endotracheal tube.
• The affected liver lobe was resected by clamping the pedicle and ligating at the site of the torsion with absorbable suture. The abdominal incision was closed in three layers with absorbable suture in a simple continuous pattern.

Case 2 (2.2 kg) – Medical management:

• Saline was given IV at 12 ml/hour.
• 2 ml high fibre paste was administered orally 3 times daily (TID).
• 0.03 mg/kg buprenorphine was given IV TID.
• 36 mg/kg meloxicam was given PO once daily (SID).
• 4 mg/kg ranitidine was administered PO BID.
• 13 mg/kg trimethoprim-sulfamethoxazole was given PO BID.
• Fine needle aspiration of the liver revealed normal cytology.

Case 3 (2.6 kg) – Medical management resulting in euthanasia (owner declined exploratory laparotomy):

• Hartmann's solution was given IV at 12 ml/hour.
• 0.02 mg/kg buprenorphine intravenously (IV).

Retrospective case series.

• Confirmation of diagnosis (histopathology on postmortem).
• Mortality.

• No rabbits survived.
• Case 1 died during recovery from surgery. The resected liver was sent for histopathology and was consistent with a liver lobe torsion.
• Case 2 died 2 days after initial presentation following medical management. A post-mortem was performed and histopathology was consistent with a liver lobe torsion.
• Case 3 was euthanised following a very short period of medical treatment.  On post-mortem 50 ml of serosanguinous fluid was found in the abdomen, and histopathology was consistent with a liver lobe torsion.

• Interventions differed between patients and data shared was reliant upon accurate record keeping/reporting.
• 1 rabbit was euthanised before any type of treatment commenced, reducing the already small sample size.
• The significance between the intervention and the outcome is unclear as no rabbits survived.
• As this is a descriptive study, that is retrospect in nature there is no control for chance, bias and confounders.
• There are no quantitative/statistical data or calculations, so there is a risk of over-interpretation.

CAB Abstracts on Ovid Platform from 1973 to 1 March 2024
PubMed accessed via NCBI interface from 1950 to 1 March 2024

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)

01 Mar 2024

• Irrelevant to PICO.
• Cadaveric study.
• Not available in English.
• Review article.
• Single case study.

Relevant to PICO question, peer-reviewed and available in English.