Leg injuries + box rest?

Far too often, the owner of a horse which has gone lame or has injured its leg is advised to restrict the horse's movement as far as possible, usually through box rest.  In order to judge whether this is truly appropriate, it is necessary to familiarize yourself with the circulation and blood vessels of the horse, and know what takes place in the tissue during the process of healing. 
 Along the horse's limbs, large blood vessels run parallel to the bones.  The blood "falls" down in the arteries, while in the veins it must "climb" back up the leg.         

What causes the blood to flow upwards over a distance of over three feet?  A 40‑year‑old (ie. relatively recent) book on hoofcare (Ruthe) states that the suction of the heart is responsible for this. Older books on horsecare (eg. Spohr) cite the circulation‑supporting pumping action of the hoof as the force returning venial blood into the body.

On account of modern knowledge about the makeup of the corium (capillary sponge) and the physical processes in the hoof (the hoof mechanism), it has been proven that a significant, circulation‑supporting pumping action takes place inside the hoof.

When one looks at the natural behaviour of the horse (eg.  Zeeb) in respect to amount and duration of movement (free living horses are always in motion, with short periods of rest lasting minutes or half an hour), it becomes clear that the circulatory system of the horse can only function properly when the limbs and hooves are more or less constantly in motion.  This means:

1. Horses which don't move for several hours (for example, when they are locked into a stall at night) have circulatory problems.
2. When the hooves are not "pumping," the bloodflow above the hoof stalls (stocked up legs, "filled" tendons, etc.)
3. Stalled blood cools, so the tissue in the area of the hooves (tissue not warmed through muscle action) also cools.
4. With lowered temperatures, cell metabolic rates drop sharply.         
5. In order for healing to take place, metabolism (blood supply, circulation) must be increased.  This is not possible when the blood is stalled in the legs because of lack of movement of the horse.        

In other words, to facilitate healing, circulation must be kept high.  This requires constant motion‑‑ but not hard exertion, or high impact from hard ground.

STALL REST AND IMMOBILISATION SLOWS OR PREVENTS ANY HEALING PROCESSES.

Copyright Dr. vet. med. H. Strasser
 
Trans.: Sabine Kells

REFERENCES

Ruthe
Spohr
Zeeb