Osteomyelitis is an infection within the bone and marrow. It can occur when bacteria enter a traumatic wound such as a bite or gunshot or secondary to penetration by a foreign object such as a nail, etc. More commonly however osteomyelitis arises as a complication of surgery on a bone usually following repair of a fracture with metal implants. Rarely osteomyelitis can develop as a result of infection being carried in the bloodstream and settling in the bone. This is more common in puppies under 2 weeks old. Most cases of osteomyelitis are caused by bacterial infections but in warmer climates fungal infections can also affect the bones.