I thought I'd share this article as it very closely mirrors my recent experience with a simple paddock injury that developed into a sequstrum (aka bone fragment) which required surgical removal. Sequestrums are something every horse owner should be aware of when dealing with a horse that's suffered an injury. Equine leg puncture wound Important information on sequestrums: Any injury that involves a puncture or impact may result in a sequestrum. This includes injuries from brushing/interference of the legs during training. Sequestrums form when blood & oxygen supply to a section of bone is lost. This can happen when a fragment of bone breaks off during impact, or the periostuem (membrane that supplies blood & oxygen to the bone) is damaged. The bone 'dies' and infection develops as the body rejects the bone as foreign matter. Sequestrums usually take 10-14 days to develop. Prior to this, the horse may appear completely sound. If the injury has been healing well but suddenly flares up 2 weeks later (e.g. sudden increase in heat, swelling, soreness, lameness) you might have a sequestrum on your hands. You will need x-rays to confirm the presence of a sequestrum. Ultrasounds can be helpful, but they aren't definitive. Sequestrums won't show up on x-rays until 10-14 days later so don't rely on x-rays taken earlier than this as proof that there isn't a sequestrum. Some sequestrums can be reabsorbed by the body on their own, but some may require surgical removal. Your vet will help you determine the correct course of action. I hope this information has been helpful! There are cases of sequestrums that have gone undiagnosed for 17 years so it's good to be aware what the symptoms are. Surgery can be done with the horse standing (sedation & nerve block), but in certain cases surgery will need to be done under general anaesthetic. Post surgery, the horse will require a minimum of 2 weeks box rest followed by 2-4 weeks of rest in a paddock. The recovery rates for sequestrums are good and generally the horse can return to normal work provided there are no other complications.