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  • 4-year-old dwarf Netherland rabbit
  • Admitted for decreased appetite and fecal production
  • Previous history: dental disease (malocclusions/ulcerations, also noted on present exam)
  • Bloodwork: elevated liver enzymes (ALT 252; AST 153); anemic (HCT 24)

 

Ultrasound video clip of the cranial abdomen (liver)

A single liver lobe is large and hypoechoic with prominent, hyper-echoic and thickened portal wall markings.  The lobe has decreased doppler signal.  The lobe is larger than expected for normal,  originating to the right of midline towards the porta hepatis, but having triangular margins that extend to the left of midline.  Surrounding peritoneal fluid is mildly echogenic. Fat surrounding the liver lobe is hyperechoic.

Diagnosis:

  • Test positive for liver lobe torsion, likely a right liver lobe
  • Echogenic peritoneal effusion, may be relate to hemoabdomen though congestion cannot be ruled out.

Comments:

The clinical presentation and imaging findings are most consistent with liver lobe torsion.  Focal liver neoplasia or other vascular compromise to the liver cannot be ruled out, but is considered much less likely.  Surgical intervention is recommended.

Surgical intervention the same day as the ultrasound exam confirmed liver lobe torsion, described as being a right liver lobe (perhaps the papillary process).  The effusion was hemorrhagic (PCV 25).  The rabbit survived to discharge with no additional complications.

Liver lobe torsion is common in the rabbit.  Ultrasound is considered the gold standard for diagnosis of liver lobe torsion because of its easy of use and low cost.1  CT has recently been used to aid the diagnosis.2

Etiologies for torsion in rabbits are speculative, perhaps related to trauma, infection or neoplasia. The most commonly affected lobe for torsion in the rabbit is the CAUDATE lobe, perhaps related to its stalklike attachment to the hilus.1,2  This is in contrast to dogs where the left liver lobes arethe predisposing lobe for torsion (left medial > left lateral).3

Ultrasound findings in liver lobe torsion include hyper echoic peri-hepatic fat, focal hepatomegaly, rounded liver lobe margins, mixed echogenicty depending on chronicity, and a “lacy” appearance.  Lack of or decreased in color Doppler markings relative to other lobes is also described.1,2

References:

  1. Daggett A, Loeber S, Le Roux AB, et al. Computed tomography with HU assessment is useful in the diagnostic of liver lobe torsion in pet rabbits (Oryctolagus cuniculus). Vet Radiol & Ultrasound 19 Dec 2020
  2. Graham J, Basseches. Liver lobe torsion in pet rabbits: clinical consequences, diagnosis, and treatment.  Vet Clin North Am Exot Anim Pract. 2014 May;17(2):195-202. 
  3. Hinkle Schwartz SG, Mitchell SL, Keating JH, et al. Liver lobe torsion in dogs: 13 cases (1995-2004). J Am Vet Med Assoc. 2006 Jan 15;228(2):242-7.