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Anatomy
The rabbit liver is divided by a deep cleft into right and left lobes, which are each divided into anterior and posterior lobules. The right lobe has a further division into the quadrate lobe, which lies caudal to the gall bladder. There is also a small, circular caudate lobe adjacent to the right kidney, which has a narrow attachment. This makes the lobe susceptible to detachment or torsion. The gall bladder is found deep within the right anterior lobule. The common bile duct joins the cystic bile duct and opens into the duodenum just distal to the pylorus. Rabbits secrete a large amount of bile (approximately 125 ml/kg per day) ( Jenkins 2000 ), and the primary bile pigment is biliverdin. The bile and pancreatic ducts open separately into the duodenum in the rabbit.
Clinical signs
Clinical signs of liver disease are generally non-specific (Box 1, Fig 1 ). Jaundice (icterus) is not common as a presenting sign in rabbits, as the primary bile pigment is biliverdin, not bilirubin, but it can be seen in severe cases.
Diagnosis of liver disease
It is important, particularly when faced with non-specific signs of ill health, to perform a detailed history and clinical examination, followed by a broad base of diagnostic tests. Clinical examination can reveal a palpably large liver, ascites, icteric mucous membranes and sclera, poor body condition, petechial haemorrhages or neurological deficits; all of these might prompt a preliminary diagnosis of liver disease.
A number of diagnostic tests are available to evaluate clinical signs that may be indicative of liver disease ( Benson and Paul-Murphy 1999 ). Once liver involvement has been established, more specific tests can be done to categorise this (Box 2).
Radiography
The liver lies mainly under the caudal rib cage. Radiographic assessment of liver size can be useful in the diagnosis of liver disease, but it is non-specific. Significant enlargement results in caudal projection of the liver beyond the rib cage margin and caudal displacement of the stomach.
Ultrasonography
Ultrasonography is a useful tool to assess both liver size and architecture. Discrete disease such as suspected neoplasia, abscessation and cystic disease, or diffuse conditions such as hepatic lipidosis may be detected. Ultrasound-assisted fine-needle aspiration or biopsy techniques can be employed...