CHAPTER NINETEEN: BONE DISORDERS & FRACTURE
Bone is a tissue, constantly replacing old cells with new ones. It is also responsible for laying down or reabsorbing mineral deposits such as calcium & phosphorous. Bone remodels based on the placed upon it. Regular exercise increases bone density, strength & resilience whereas inactivity decreases bone density, causes demineralization and weakens the structure. Minerals are laid down in layers beneath the periosteum which can take several weeks. When excessive forces or stresses are placed on the bone, abnormal responses can occur. This includes; Exostoses/Osteophyte – Sclerosis – Demineralization – Fracture –
Periostitis and Ostitis
Periostitis is defined as inflammation of the periosteum and ostitis is defined as inflammation of bone tissue. These two conditions are closely linked and are commonly seen together.
Periostitis is a result of repeated
in the form of micro-tearing of the
periosteum by tendons that attach to it or joint or bone instability.
The micro-tearing causes local inflammation that compresses the blood supply of the bone. Without a blood supply the bone tissue experiences ischemia and becomes inflamed. Ischemia of the outer cortex of bone forms a thin layer of necrotic bone tissue that is called a . The body surrounds the sequestrum with granulation tissue and may eventually expel it from the body through the skin. If expulsion of the sequestrum is not possible osteoclasts act to break down the healthy bone surrounding the sequestrum, and osteoblasts lay down new bone between the sequestrum and the periosteum. This is called an .
Periostitis and ostitis are commonly seen in young racehorses when they begin intense training.
Clinically periostitis and ostitis are seen as pain on palpation of the affected site, lameness that increases with work and heat and inflammation over the affected site. In severe cases where a
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