Causes
Road accidents, falls, blows, being trodden on (common in rabbits and small animals), fights. Osteoporosis or certain tumours can cause a bone to break with a minor knock.
Diagnosis
X-rays to confirm the fracture and plan treatment.
Treatment
EMERGENCY: pain control, immobilisation and, depending on the fracture, rest with a splint or surgery. Do NOT try to splint at home: you may make the injury worse. Move the animal carefully, without handling the area.
Prevention
Avoid falls and accidents, hold rabbits and birds securely when handling them (their bones are fragile), supervise small animals.

