The arterial supply of the navicular bone and its variations in navicular disease.

This study investigated the blood supply routes in the navicular bone (a bone in a horse’s foot) and their relationship to navicular disease, a common cause of lameness in horses. The researchers examined the navicular bones of 83 horses, finding two main blood supply routes; one present at birth and another that develops with growth and activity of the horse. Changes in the shape and size of the nutrient foramina (canals in the bone that allow blood vessels to pass through) on radiographs were linked to the type of work horses were involved in as well as navicular disease.

Investigation of Blood Supply

• The research involved a comprehensive study including macroscopic, microscopic, and radiological examinations of the navicular bones.
• The navicular bones of 83 horses and ponies served as the basis for the study. This broad sample base made the findings more valid and applicable to the general population of horses.
• It was found that the navicular bone in these horses had two main routes for blood supply. One supply is innate, present at the birth of the foal, while the other evolves within the first 2 to 3 years of life, indicating a developmental aspect linked to the horse’s growth and increased activity.

Nutrient Foramina and Vascular Disease

• The researchers discovered a correlation between the shape and size of the nutrient foramina and the type of work the horses performed.
• The nutrient foramina are essential openings in the bone which allow for the passage of blood vessels.
• The regular size and shape of the foramina should be conical. An alteration in this shape, notably a change to a circular or mushroom-shape, is indicative of vascular disease in the navicular bone. These physical changes are observable on a standard antero-posterior radiograph of the bone.

Navicular Disease and Lameness

• Navicular disease is a common cause of lameness in horses and is often associated with the ischaemia of the navicular bone – a condition where blood supply to the bone is reduced.
• This reduced blood supply is triggered by the occlusion, or blockage, of blood vessels. According to the research, the occlusion of at least two primary arteries and some involvement of the compensating collateral blood supply must occur prior to lameness resulting.