Contracted heels are problematic for several reasons:
- They can lead to atrophy of the internal structures of the hoof, which are necessary for support and correct functioning of the entire hoof.
- Contracted heels also affect the health of the frog tissue. Contraction can lead to the blood supply to the frog’s corium being compromised, both by the walls squeezing in and by the horse avoiding the back of the foot when landing. The frog cannot grow healthily in these conditions, so it thins out and is less thick and calloused than it should be. The result is less material to protect the sensitive inner structures of the hoof and absorb concussive forces, so increased force is transmitted to the joints above the hoof. Ultimately, this becomes a vicious cycle – the horse doesn’t land on the back of the foot, so the back of the foot becomes weaker and painful, so the horse is even less likely to land on the back of the foot.
- The walls of the contracted foot shifting inwards also causes the frog, the collateral grooves, and the central sulcus to get narrower, which not only shrinks the ‘landing area’ of the foot, resulting in poorer shock absorption but also creates a haven for dirt and infection. Since the health of the frog is already compromised in this situation, it is very easy to end up with thrush – an infection of the frog caused in most cases by the anaerobic bacterium Sphaerophorus necrophorus. This creates further pain at the back of the foot, further reducing the likelihood of a correct, heel-first landing.
- Contracted heels are not always fixable. Most of the time the condition is reversible, at least to some extent, with correct trimming or shoeing and extensive turnout on varied terrain. However, there are instances where a contracted foot is not going to improve very much. Long-term contractions, whatever the cause, can lead to the coffin bone remodeling to fit the narrow shape of the hoof. The lateral cartilages can also reshape at this point so that they hook inwards at the rear, and once in this state, they commonly ossify to form sidebone. If your farrier is struggling to de-contract the heels, it may be worthwhile getting an X-Ray to see if any permanent changes have occurred in the feet. An X-Ray can also help your farrier to see what can be done to optimise the health and functionality of the hoof for your horse.