Limb fracture and pinning of the broken bone
Esther van Praag Ph.D.
Warning: this page contains pictures that may be distressing for some persons.
Rabbits are preyed-on animals, which must be able to flee and run rapidly. Their limbs are therefore powerful, while their skeleton is light, and comprises only 7 to 8% of the body weight. In comparison, the skeleton of a cat makes up about 12 to 13% of the body weight. Spine and limbs are thus more prone to fracture in rabbits, as compared to other animals.
Back injuries are often observed at the lumbar level. Additional health problems, like osteoporosis and/or low calcium diet can render the bones brittle and fracture can happen when a rabbit panics, is improperly restrained or picked up, or dropped. The result is often paralysis of the lower limbs, accompanied by incontinence.
Fracture of the tibia is another danger in rabbits. They are often caused by improper handling, or caging, when a limb becomes trapped in improperly sized wire mesh. Fractures of limbs are often comminuted (more than two broken pieces of bone). Fractures in lower limbs (below elbow) are often open, due to the minimal presence of soft tissue. They are often difficult to treat, and need to be mended with patience, in order to avoid further tearing of the skin. The wound must be sterilized, and the fractured bone pinned or splinted if the lower part of the limb is affected. Osteomyelitis (bone infection) and/or gas gangrene can quickly set, and should be treated appropriately with broad-spectrum antibiotics. It is furthermore advisable to do a bacterial culture, in order to determine which ones (aerobic - anaerobic) have possibly contaminated the wound.
Diagnosis and first aid
A rabbit that has a broken limb does not necessitate emergency medical care, unless there is shock, bleeding, respiratory or cardiovascular problems. Immediate pain medication is recommended, in order to comfort the rabbit and keep him/her quiet.
X-rays and a complete physical and neurological examination must be done in order to determine the damage, further treatment and prognosis of wound healing.
Use of intramedullary fixation
The technique of intramedullary pinning is of common use in small animals and is relatively simple. It requires nevertheless patience and technical expertise, associated to a good understanding of biomechanics and healing of fractured bones.
Intramedullary fixation is optimal for use in rabbits as the implant will help give bear the weight of the body, although healing-time may be delayed. Steinmann pins, Kirschner wires and/or cerclage wire is commonly used in rabbits. Smooth intramedullary pins are preferred over partially or fully threaded pins. In dwarf or small rabbit breeds, the pin can be replaced by a (hypodermic) needle. The pin or needle must, however, imperatively take 60 to 70% of the medullar center.
The Steinmann pin is usually inserted by hand or by means of a Jacobs chuck. It can be inserted either at the fracture site (retrograde insertion) or at the end of the bone (normograde insertion) and be driven through the fracture site. The protruding end of the pin is cut, in order to avoid damage of the skin, bacterial infection, or interference with the joint, unless an external skeleton fixation system is used, in which case the pin should be left protruding.
Open fracture repair techniques necessitate appropriate sterile working conditions, accompanied by profuse cleaning of the surgery site.
According to the location of the fracture, padded bandages, auto-adhesive bandage or casts can be used.
Post-surgical care includes regular examination of the mended fracture for bacterial infection, loosening of the pin or needle, and fracture healing. The removal of the pin is based on X-ray pictures. It is usually around 6 weeks post-surgery. In rare cases, where the health of the rabbit is affected, the pin can be left in the bone.
Pain is a signal that leads to a decreased use of the body part, in order to avoid further damage. It is deleterious, as lack of use and spasms lead to weakness, loss of muscle tone, and irreversible damage. Pain medication is thus very important. A good choice of analgesics is available for orthopedic pain:
See “Analgesics drugs for use in rabbits” for dosages.
Pain will moreover cause a loss of appetite and decreased water intake. It is thus important to keep the rabbit well hydrated.
All my gratitude to Sandy Minshull and Akira Yamanouchi (Veterinary Exotic Information Network, http://vein.ne.jp/), for the permission to use their pictures. Thanks also to 11 year old Herman.
Flecknell P. BSAVA Manual of Rabbit Medicine and Surgery, UK: British Small Animal Veterinary Association; 2000.
Hillyer E.V. and Quesenberry K.E. Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery, New York: Saunders; 1997.
Manning P.J., Ringler D.H., Newcomer C.E. The Biology of the Laboratory Rabbit, New York: Academic Press; 1994.
Richardson V., Rabbits: Health, Husbandry and Disease. Blackwell Science; 2000.