Caudal Heel Pain Syndrome
Caudal heel pain syndrome is sometimes called navicular syndrome but it can include structures not associated with the navicular so this is a more inclusive term.
Lameness is usually slow onset or chronic and relatively low grade at least at first. Horses with long sloping pasterns and obvious low heels are predisposed.
Pain on hoof testers in the heels or across both heels is a good indicator of caudal heel pain. Your vet may then administer nerve blocks where local anaesthetic is injected over the nerves to deaden feeling to different areas to help localise the pain.
Long toe and low heel conformation either natural or due to inappropriate trimming exacerbates heel pain as the horse takes more of its weight through the heel. The compression of the heels can then cause them to grow slower making the problem worse over time.
Radiographs of the feet are essential to check the alignment of the bones and the hoof capsule. Best results are obtained when the vet and farrier can work together and the radiographs can give important information to the farrier to start realigning the hoof capsule. In the normal foot, the ground surface of the coffin bone should be higher at the heel than at the toe. In many horses with caudal heel syndrome, the sole depth at the heel is less than that at the toe so the bone is actually pointing up at the toe instead of down. Hopefully the radiographs will show enough sole depth that the hoof capsule can be realigned by removing toe depth and length. Reducing the breakover by rolling or squaring the toe is essential regardless. Often the heels may need raising short term as well using wedges or other special shoes which is why consultation with a farrier can be so important. If the frog is healthy, properly placed heartbar shoes transfer weight onto the frog and can help relieve heel pain and compression.
To make this syndrome more confusing, xrays can sometimes be normal as many of the structures involved are soft tissues. Ultrasound is restricted in this area but can still be useful. MRI though often the best imaging modality is very expensive and is found in very few places in Australia.
At least initially oral non-steroidal pain relief such as bute are helpful along with rest and changed or reduced use.
Injections into the coffin joint or navicular bursa may be required for further diagnostics and/or treatment.
There are compounds known as bisphonates such as tildren which is given IV by a veterinarian or osphos which is an intramuscular injection which are useful to reduce bone resorption in navicular syndrome. They are relatively expensive, cannot be used in racehorses and withholding periods apply in competition horses.