Bone fracture in rabbit: causes and treatment

Bone fractures, the medical profession speaks of fractures, are not uncommon in rabbits. Especially the limbs such as hind legs, toes or even the front legs are particularly predestined.

Bone fractures in rabbits are mainly caused by jumping from a great height, for example from the owner’s arm, or by trapping or hanging limbs with subsequent attempts to free them.

A bone fracture in a rabbit should be presented to the veterinarian immediately, as it is associated with great pain.

Structure and composition of bones

In contrast to many other animals (and us humans), rabbits have a very fine bone structure in relation to their body weight.
A comparison
If you put this in relation, the bones make up 12 percent of the total body weight in us, in rabbits it is only 6 percent.

Each bone consists of the periosteum, which surrounds the bone from the outside. It contains numerous blood vessels and serves as a source of nutrients.

Depending on the type of bone – whether tubular bones of the limbs, flat bones of the sternum or skull, or the irregular vertebral bones – the bone consists of solid lamellae on the outside and an internal beam structure whose cavities are filled with bone marrow. This makes bones elastic on the one hand and very resilient on the other.

Due to the interaction of certain cells, the osteoclasts and osteoblasts, bones are also subject to constant renewal. While the osteoclasts remove old and damaged bone substances, the osteoblasts make up for this missing bone substance.

To do this, however, the bone must be optimally supplied with nutrients and sufficient movement. If this is not the case, there is an imbalance of osteoclasts and osteoblasts and the bone substance loses stability.
Bone fracture from an anatomical point of view

Due to the special ability of bone to adapt to constantly changing requirements, it is not only capable of compensating for defects, but also of resealing broken bone substance.

In this process, a replacement tissue, the so-called scar tissue, is not formed, as is the case with other tissues of the body. If a bone breaks, the fracture site is replaced by original tissue, i.e. a new bone substance is formed at the fracture site that is both resilient and elastic.

For this to happen, however, the fracture sites must be “healable”, i.e. they must lie in front of each other, which is what the medical profession calls a smooth fracture. If the fracture sites are displaced from one another or if fragments are missing, these must be surgically straightened in order to achieve healing of the fracture with a stable result.

In the case of a splinter or comminuted fracture, fracture healing is not possible without surgical measures, and in severe cases only amputation or euthanasia is possible.

Causes of bone fractures in rabbits

Why rabbit bones break can have several causes.

On the one hand, bone fractures can be due to mechanical impact. The rabbit as a flight animal is enormously nimble and agile. Especially when it comes to escaping from the arms of the rabbit owner, these abilities can be its undoing. Jumps and falls from great heights are not always withstood by the rabbit’s bones.

Getting caught, for example, on carpet fringes, hay trellises, or other “trouble spots” can also lead to fractures when the rabbit tries to free them. Toes and limbs are particularly susceptible to this.

Another issue with regard to bone fractures in the domestic rabbit can be nutritional and husbandry errors. As mentioned at the beginning, healthy bones are dependent on proper nutrition and exercise. Feeding errors with a deficiency or excess of certain nutrients important for healthy bone substance, such as calcium and vitamin D, make the bones susceptible to defects.

Hormonal issues can also affect bone stability. Finally, it is exercise that plays a major role in bone health. A certain amount of exercise is necessary to activate the bone cells and thus maintain a balance in the formation and breakdown of bone substance.

Good to know
Exercise also keeps muscles, ligaments and tendons fit, which ultimately serve as support for the skeletal system and protect it from damage.
Symptoms of a bone fracture in rabbits

The first and also probably most obvious sign of a broken bone in a rabbit is the sparing of the affected limb.

It is not uncommon to observe an abnormal position of the broken limb. If the rabbit limps and/or drags a limb, a veterinarian should always be consulted.

Broken bones cause severe pain, even when rabbits do not communicate by wailing sounds of pain.

Often, therefore, eating is also stopped because of pain.

If not the limbs are affected by a fracture, but the rabbit has broken the pelvis or the spine, a locomotion is hardly possible. Such fractures become visible mainly by abnormally protruding legs or a complete inability to move.
Diagnosis of fractures in rabbits

The veterinarian can usually make a tentative diagnosis based on the anatomical changes visible from the outside.

Palpation and a manual functional test (a rubbing noise may be perceived) of the affected areas also provides initial information.

Together with the questioning of the rabbit owner about possible accidents, jumps or the like, this first diagnosis is already substantiated.

A fracture in the rabbit can be determined with certainty using imaging techniques. For this purpose, the affected structure is x-rayed, whereby the x-ray image not only provides information about a possible fracture site, but also about the extent of the fracture and the further treatment steps.

Treatment of a fracture in rabbits

The treatment of a fracture in rabbits is composed of several pillars:
Pain management

Because fractures are very painful, many rabbits stop eating completely. Therefore, the treatment of a fracture always includes pain therapy.

However, the dose is chosen so low that still a protection of the affected area is achieved. A painless, lively hobbling rabbit with a broken leg is not the goal and not conducive to a complication-free healing! 
Antibiotics

If the fracture is an open fracture, meaning the bone has penetrated the skin, the veterinarian will prescribe an antibiotic in addition to a painkiller to keep the risk of infection as low as possible.

The same applies to surgical treatment of a bone fracture. Here, too, an antibiotic is administered as a precautionary measure following the operation.
Treatment of fractures

For smooth and uncomplicated fractures, immobilization of the affected limb is usually sufficient. Splinting the fracture site, however, is only possible for fractures on the limbs (front and hind legs, and toes).

In the case of complicated fractures, surgery is sometimes unavoidable. In this case, the affected fracture site is brought into position with the help of nails, plates and wires in such a way that healing of the fracture sites together becomes possible.

In some fractures, for example comminuted fractures, where the bone has been blown into numerous small bone fragments, it is not always possible to straighten the fracture site surgically. In such a case, amputation of the limb is then necessary.

If bones are affected that cannot be immobilized or splinted (pelvis, spine), or are so badly damaged that healing is not possible, the only option is to euthanize the rabbit to spare it great suffering.
At home

Back in the home cage, it must be prepared according to the new situation.

• The run must be limited accordingly, or the rabbit must be moved to a small enclosure.
• All elevations must give way from the cage, so that these are not climbed.
• Accordingly, a cottage with a pointed roof can be very useful as a shelter, and a cuddly den made of fabric is also suitable.
• The floor of the rabbit hutch must be padded as softly as possible for the period of recovery and be non-slip. In the case of open wounds, if for example an external fixator had to be applied to bring the bone into position, bedding should be avoided to prevent contamination of the wound. In these cases, an old carpet (without loops and fringes) will serve well as a stable floor.

Preventing fractures in rabbits

The best prevention against a fracture in rabbits is an optimal supply of all important nutrients and a sufficient amount of exercise.

In addition, the general housing conditions, starting with the barn equipment (possible danger spots in which the rabbit can get stuck) to the run or free run (fall possibilities, getting stuck in the carpet due to too long claws, getting stuck in doors).

Handling the rabbit can also help prevent fractures. For example, the pelvis should always be supported when picking up the rabbit and the rabbit should be secured when being carried so that it cannot suddenly jump out of the arm (children!).