The sacrum is a triangular bone at the base of the spine which is wedged between the hip bones of the pelvis. It consists of 5 sacral vertebrae which are seperate at birth but are fused together by the time the horse is an adult. Cranially it conects to the last lumbar vertebra and caudally it connects to the first coccygeal (tail) vertebra. The connection to the pelvis is a firm fibrous joint with a limited range of movement known as the sacroiliac joint.

A saddle joint is a biaxial joint which allows movement in two planes. It consists of two saddle shaped joint surfaces positioned at right angles to each other.

An axis which runs through the centre of a structure (e.g. the hoof) and splits it into two more or less equal halves. 

An axis which runs through the centre of the hoof and splits it into two more or less equal halves. Can apply to the frontal or solar view.

Anatomical plane which runs perpendicular to the ground in a cranio-caudal direction (from head to tail). The median is the sagittal plane which runs throught the middle of the body and divides it into two equal halves. 

Tumorous growth affecting the skin of the horse. It does not affect any other organs. Various types are seen:
Verrucous: wart like growth in an on the skin
Nodular: firm, subcutaneous roundish nodules
Occult: circular patches of altered/thickened skin with thin haircoat, occasionaly with small nodules
Fibroblastic: fleshy, ulcerated and usually rapidly growing masses.

Horses of all ages can be affected and it can be extremely difficult to treat, as surgical removal is often followed by a recurrence. The exact cause is unknown although the Bovine Papillomavirus BPV is known to be involved in many cases. Particularly large tumors or an unfavourable location such as in the girth region can lead to loss of use of the horse.

A form of interference where the toe of a forefoot hits the dorsal or medial aspect of the hindlimb on the same side. The point of contact may be anywhere between the hoof wall and the cannon region. Most frequent the point of contact is the coronary band.

A flat wedge shaped bone that is the most proximal bone of the forelimb. It is firmly attached to the ribcage with fibrous tissue. Articulates with the humerus (upper arm bone) to form the shoulder joint at its distal end.

Scintigraphy is form of diagnostic imaging which involves the administration of radioactive substances. Whereas in radiology and computed tomography external radiation passes through the object being studied, the radioactive isotopes administered intravenously prior to scintigraphy cause radioactive emition directly from the object. This radiation is detected by a special camera (gamma camera) and represented as an image on a screen. A higher concentration of radioisotopes is found in tissue that is subject to increased function. This may be due to physiological factors (joints always show more activity than bone shafts) or may be the result of pathological changes such as inflammation or fracture repair. These areas will show up as 'hot spots' - areas of increased radioactivity.

Hardening or solidification of tissue and organs through an increase in fibrous connective tissue. The possible causes include chronicinflammation, disturbances in the blood supply or the normal aging process.