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. Most cases of osteomyelitis are caused by bacterial infections but in warmer climates fungal infections can also affect the bones. Osteomyelitis is more common in dogs, but it can also affect cats with much less frequency.