is another condition involving periostitis/ostitis. The sesamoid bones are important in supporting the fetlock joint as part of the stay apparatus. They ensure that the flexor tendons glide smoothly over the back of the fetlock. When the fetlock hyperextends the sesamoids are between the cannon and 1 st phalanx bone. This compresses the body of the PSB. At the same time, supporting ligaments exert tension on the edges of the PSB and can disrupt blood supply to the bones. This can result in inflammation of the PSB and cause loss of density, exostosis and fracture. Long sloping pasterns with long tow, low heel conformation predispose for sesamoiditis as well as young racehorses doing too much too soon on hard surfaces. It is often seen in the forelimb. Horses show signs of lameness, resist fetlock flexion, pain on palpation and heat over the back of the fetlock. Surrounding soft tissue may also be affected and show local signs of inflammation. X-ray is the most common way to diagnose sesamoiditis. Treatment is the same as for bucked shins. Prognosis is excellent as along as the horses was properly treated and didn’t return to work too soon or too intensely.
Osteonecrosis
Osteonecrosis is defined as the death of bone tissue
the presence of infection.
Osteonecrosis is caused by leading to the hypoxic death of osteocytes, osteoblasts and osteoclasts and the inflammation of bone tissue. This is often the progression of periostitis/ostitis if it is not treated. Compression of the blood vessels that supply a section of bone causes ischemia and hypoxia, which leads to ostitis and periostitis. Inflammation causes swelling, which puts further pressure on the blood vessels and eventually causes the death of a section of bone. Sequestrum formation occurs around the necrotic area, increasing the chance of pathological fracture. The chance of infection is also increased inside the sequestrum as leukocytes are not able to penetrate into the necrotic area.
Predispositions include improper
technique, a peripheral vascular disease
or a hematoma in bone.
The signs and symptoms of osteonecrosis are similar to those of periostitis/ostitis. Pain, heat, swelling with lameness and sequestrum formation. Nuclear imaging may reveal decreased perfusion to an area of bone though such imaging is costly and impractical in the horse. Diagnosis is generally made through radiography revealing pathological fracture or sequestrum formation as well as a history of peripheral vascular disease, hematoma, or uncontrolled haemorrhage. Treatment is to remove or treat the primary condition. Rest with cold hydrotherapy and anti- inflammatory therapy is beneficial for supportive care.
190
Made with FlippingBook Publishing Software