The arterial supply of the navicular bone and its variations in navicular disease.
Authors: Colles, Hickman
Journal: Equine veterinary journal
Summary
# Editorial Summary: The arterial supply of the navicular bone and its variations in navicular disease The navicular bone's blood supply develops in two distinct phases: an initial system present at birth, followed by a second vascular route that establishes itself within the first 2–3 years as the horse increases its workload in response to activity demands. Colles and Hickman examined 83 horses and ponies using macroscopic, microscopic and radiological techniques, revealing that the morphology of nutrient foramina visible on standard anteroposterior radiographs directly reflects the type, frequency and regularity of work undertaken by each animal. Critically, conical foramina indicate normal vasculature, whilst alterations to circular or mushroom-shaped configurations suggest occlusive vascular disease within the bone itself. The research demonstrated that navicular lameness results from ischaemia caused by progressive arterial occlusion, but only when at least two primary arteries are compromised alongside significant involvement of the collateral circulation. For practitioners, this work provides a radiographic framework for identifying vascular compromise before clinical lameness emerges, and explains why some horses develop navicular disease whilst others with similar work profiles remain sound—differences in arterial redundancy and collateral development appear crucial to disease susceptibility.
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Practical Takeaways
- •Radiographic changes in nutrient foramina shape (circular or mushroom appearance) are diagnostic indicators of vascular compromise in navicular disease and can guide clinical decision-making
- •Progressive work conditioning normally develops secondary blood supply in young horses; understanding this timeline helps distinguish normal development from pathological vascular changes
- •Navicular lameness requires significant vascular compromise—single artery occlusion alone is insufficient, so multiple arterial involvement must be confirmed before attributing lameness solely to navicular ischaemia
Key Findings
- •Adult horse navicular bone has 2 principal blood supply routes: one present at birth and one developing within 2-3 years in response to activity
- •Nutrient foramina size on radiographs correlates with type, frequency and regularity of work performed
- •Alteration of nutrient foramina from conical to circular or mushroom shape indicates occlusive vascular disease, visible on standard antero-posterior radiographs
- •Lameness from navicular ischaemia requires occlusion of at least 2 primary arteries plus involvement of compensating collateral blood supply