The liver, a delicate organ in rabbits

Michel Gruaz - Esther van Praag, Ph.D.

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The liver is a large organ that occupies a big part of the rabbit's abdomen. Its surface is homogeneous, with a red-brown color. The liver has endocrine as well as exocrine functions, with the secretion of bile.

The liver of rabbits has 2 major lobes, right and left, which are separated by a median fissure in between them, in which the accessory lobes are located: the caudate lobe and the square lobe. The liver is maintained in place in the abdominal cavity by ligaments connected to the diaphragm and to the dorsal wall of the abdomen. The liver plays a central role in the synthesis of proteins, in the metabolism of sugars and the storage of nutrients, in the degradation of toxins and the treatment of organic waste produced by cells of the body. It has, furthermore, an exocrine function with the secretion of bile. This balance can be broken during a disease, the presence of bacteria, parasites or toxins in the diet. Liver disorders are poorly recognized in rabbits because the clinical manifestations are vague and not very characteristic.

Single and double gall bladder

The gall bladder is a hollow, pear-shaped organ that lies against the liver in the caudal surface depression. It produces bile, a viscous yellow-greenish liquid that is released into the small intestine via the bile duct. This secretion promotes the digestion of fatty foods. In rabbits, bile is produced continuously and is stored in the gallbladder before its release into the small intestine. Bile of rabbits is mainly composed of biliverdin, which has strong antioxidant properties, and not bilirubin. The quantity of bile produced by this animal per day is enormous: about 250 ml. Based on weight, this is 7 times the amount produced by a dog.

Normal rabbit liver and gallbladder (arrow)

A double or bilobed gall bladder is a rare observation. The duplication of the gallbladder takes place during the embryonic phase. The gallbladder is subdivided, and results in two complete vesicles of normal size and volume. Their respective ducts transport bile to the intestine. These ducts can merge halfway or remain separate. The duplication of the gallbladder seems to affect herbivores more than carnivores or man: 1 case out of 28 in cattle and 1 case out of 85 in sheep. Some cases have been reported in rabbits too. Various clinical manifestations are associated with this congenital anomaly: pain and loss of appetite. In other animals, a duplicate gall bladder is often associated to biliary colic, acute inflammation of the gallbladder or the presence of gallstones.

Michel Gruaz

Liver and double gallbladder (pocket filled with green liquid - arrows) in a Harlequin rabbit aged 3 months. Since weaning, this rabbit had regular digestive problems and weighted only 2.3 kilos, while his littermates weighed 2.8 kg.

Liver lobe torsion

The torsion of a lobe of the liver is a sporadic (non-hereditary) event whose cause is not well clarified. Most likely it seems linked to an abnormal dilatation of the stomach and intestine after an intestinal obstruction. Ligaments holding the liver in place in the abdomen are distended and weakened, allowing the twisting of a lobe. Other causes include external trauma, bacterial or parasitic infection, or congenital absence of ligaments. A predisposition has been suggested in Madagascar lop rabbits. But this remains to be verified as the line of affected rabbits could not be established. Gestation is not a cause of hepatic lobe torsion in rabbits or other animals.

In 63% of cases, torsion of the caudate lobe is observed in rabbits. This lobe is attached to the liver on a very small surface only, facilitating its movement in the abdominal cavity or its torsion. Blood circulation is then hindered, causing atrophy of the lobe. Its consistency becomes hard and it takes a dark color. The condition is painful and leads to decreased appetite, shock and death after a few days. If the lobe ruptures, the resulting hemorrhage causes death quickly. A minority of rabbits survive when they receive supportive care consisting of oral food assistance with a syringe, sterile subcutaneous fluids, analgesic, antimicrobial/anticoccidial, and other intestinal motility drugs (1 to 2 cc of olive oil is effective too).

Michel Gruaz

Liver with torsion of the small caudal lobe and content of the caudal lobe.

Bacteria, coccidia and parasites

Bacteria can invade the liver and cause abscesses. The most common bacteria are Pasteurella sp. or Escherichia coli. When in contact with birds or cattle, the rabbit's liver can also be infected with salmonella, listeria or Yersinia sp., which causes pseudotuberculosis. As for the parasitic protozoa infecting the rabbit's liver, they include those causing coccidiosis (Eimeria stiedae) and toxoplasmosis. Coccidiosis affects young animals. Their digestive system is particularly sensitive to this parasite during the food transition from milk to vegetable food, which is more difficult to digest. Signs of infection include a decreased appetite, diarrhea, mucus between hard droppings, weight loss, and death. The young rabbit often has a swollen belly. Older and healthy rabbits develop some immunity against this parasite. Examination of the liver reveals the presence of yellow-colored nodules on the surface that are difficult to differentiate from a bacterial abscess.

Michel Gruaz

These white structures are difficult to differentiate between abscess and coccidia.

Parasitic worms of the liver are rather occasional in rabbits, after ingestion of food contaminated by snails, dogs or foxes. The rabbit does not host the adult parasite, but an intermediate form. These are mainly the great liver fluke (Fasciola hepatica) present in the grasslands, dog tapeworm (Taenia sp.) and the fox worm (Echinococcus multilocularis). The two latter form hydatid cysts containing the larvae of the parasite. These cysts can take a certain volume in the abdomen and compress the rabbit's liver. Few clinical signs indicate the presence of these worms in live rabbits.

Toxemia and liver lipidosis

Pregnancy toxemia is a serious disorder caused by a disruption of the energy metabolism in the late gestational rabbit. Intrauterine growth of fetuses requires a lot of energy. If this demand is not met with a high-calorie diet, the blood glucose level of the doe drops rapidly. The adipose tissues are mobilized and start to release fats into the blood, poisoning the body. The liver does no longer functions properly and does not eliminate ketone bodies. Other vital organs are also affected, like the kidneys. The pH of the urine decreases (5-6), its color is clear and it is low in sediments, but it contains ketones and proteins. The intestinal transit is decreased or even stopped. The occurrence of diarrhea and/or a decrease in the amount of produced droppings are common. At autopsy, organs such as the liver, thyroid, heart, kidneys and adrenal glands are very pale. These organs may have greasy infiltrations and necrotic foci. The stomach contains only a little food. Hemorrhages are visible in the placenta and uterus. Another consequence of a difficult gestation or lactating of a large litter is hepatic lipidosis. The alternation of feeding followed by refusal to eat causes an accumulation of fats in the liver and kidneys of the doe. Their functioning is altered. The rabbit eats less and less, becomes lethargic and loses weight.

Other causes of liver lipidosis include dental problems or a diet low in fiber. Rabbit obesity is also characterized by an abnormal accumulation of fat in liver cells linked to a diet that is too rich in sugars (and not in lipids). Instead of metabolizing them and removing excess, the liver stores lipids in its tissues.

Michel Gruaz

Pale liver in a doe that died from gestation toxemia.

Toxins, gas fumes and pesticides

Various toxins affect the rabbit's liver and alter its functioning. Aflatoxin of fungal origin is contained in cereals contaminated by molds. It is very toxic to the liver and can lead to death quickly. Plant toxins are suspected of causing neurological problems such as the head down syndrome. The rabbit keeps its head down, unable to raise it, keeps its back arched and often refuses to move and to feed itself. The severity varies from case to case. Some rabbits recover after a few days while others do not survive. Lead and heavy metals also cause serious dysfunction of the liver. The use of pine sawdust or cedar, vermiculite should be avoided in a cage or a hutch, even if their smell is pleasant. Indeed, the emanations of these products have a toxic effects on the liver.

Pesticides affect the nervous system, with signs of hyperactivity, hypersensitivity and/or paralysis accompanied by breathing difficulties, diarrhea, hypothermia and/or nasal bleeding. Younger rabbits are more sensitive and more affected than adults. The general state of health and nutrition of the animal also plays a role. Treatment is essentially supportive, helping the rabbit with assisted syringed food and fluids to prevent dehydration. Autopsy of intoxicated rabbits shows that the liver has a pale color with cellular hypertrophy and fatty degeneration. These disorders often precede the coma and death of the animal.

Typical hunched position of a female rabbit, with paralysis of the hind-limbs, after a pesticide intoxication.

Lungs of the above rabbit, showing multifocal hemorrhagic regions (arrows) in the lungs.

Deformation of the spinal cord

A less common cause of liver disease is bone deformity of the spine, such as lordosis, which is observed sporadically in rabbits. The curvature of the spine towards the inside of the abdomen causes pressure on the abdominal mass and compression of the blood vessels draining the blood from the heart to the organs and vice versa. Liver and kidneys are mainly affected. In the liver, blood flow from the inferior vena cava is restricted, resulting in a reduced hepatic activity. The secretion of bile into the intestine is decreased, leading to a poor digestion of the ingested food. As a result, toxins accumulate in the liver, which takes a congested appearance, with a dark red color, a size slightly larger than normal, and rounded and rough edges. Passive congestion of the liver may be secondary to heart failure.

Michel Gruaz

Incidetal finding upon necropsy: lordosis of the spine (arrow) and congested liver in a young Champagne Silver rabbit.

The spinal deformation is accompanied by liver congestion, a possible consequence of compressed blood vessels from the heart to this organ.

Finally, the rabbit's liver can develop cancerous tumors or bile duct tumors. Liver diseases are so numerous and often difficult to detect in rabbits. Indeed, signs are not very characteristic in addition to the fact that the rabbit has a tendency to hide the presence of a disease. Remains the observation: droppings, their smell and shape, the presence of mucus, amount of water drunk, in addition to veterinary tests to establish more precisely a liver disease.

Further information

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Cox JC, Edmonds JW, Shepherd RC. Toxoplasmosis and the wild rabbit Oryctolagus cuniculus in Victoria, Australia with suggested mechanisms for dissemination of oocysts. J Hyg (Lond). 1981;87(2):331-7.

Coudert P., Licois D., Drouet-Viard F., Provôt F. 2000. "Coccidiosis". In: Rosell J.M. (ed), (Enfermedades del conejo), vol.II, chapter XVI, pp 219-234, Mundi-Prensa Libros, Madrid, Spain.

Dubey JP, Passos LM, Rajendran C, Ferreira LR, Gennari SM, Su C. Isolation of viable Toxoplasma gondii from feral guinea fowl (Numida meleagris) and domestic rabbits (Oryctolagus cuniculus) from Brazil. J Parasitol. 2011;97(5):842-5.

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