What is navicular disease?
Navicular disease (or syndrome) is a common diagnosis in horses causing significant pain and lameness. It falls under the umbrella term of “palmar foot pain” which means pain arising from the palmar (towards the back and in the heel) region of the hoof. The navicular bone sits centrally within this region but is adjacent to several other structures, all of which can be damaged or inflamed. Pain in the palmar foot can originate from the.
- Navicular bone
- Deep digital flexor tendon (DDFT)
- Navicular bursa
- Ligaments in the region – the collateral sesamoidean and impar ligaments
- Coffin joint (distal interphalangeal joint)
- Coffin bone (P3 – third phalanx)
- Digital cushion
- Hoof capsule
How do you know if your horse has navicular?
The first step to diagnosis is physical and orthopedic examination. Lameness and pain can manifest variably and while in some cases there may be marked lameness like a ‘head nod’ other horses only show subtle shortness of stride. In some the only symptom may be stumbling, since horses with navicular/heel pain tend to land toe first.
Visual examination of the hoof can give some insight into those horses that are predisposed to pain in the region. Hoof tester response, when positive, is useful for identifying navicular pain but can have false negatives. The best and most useful test is examining the horse at a trot and assessing the response to local anesthetic nerve blocks.
Confirming the diagnosis?
Horses that block to the heel region should have a complete radiographic series performed first. In most instances this is sufficient to help start a treatment plan. In some cases, when no abnormalities are seen, MRI is needed to provide a specific diagnosis which allows us to create a tailored treatment plan. While MRI is costly, the information that can be gathered from this imaging modality can have tremendous benefits in long term treatment planning.
Treating navicular disease and palmar heel pain
Treatment of navicular disease/palmar heel pain is centered around correcting hoof balance. While no single treatment package works every time, there are general principles that can be followed:
- Correct any pre-existing problems e.g., underrun heels, contracted heels, sheared heels and hoof pastern axis.
- Trimming and shoeing must allow for even weight bearing of the hoof.
- Allow the hoof to expand.
- Encourage break over at the toe.
Assuming these principles are followed, and can be achieved, many horses will respond very well. It is oftentimes recommended that these horses receive anti-inflammatory medication in the form of phenylbutazone OR firocoxib.
Specific treatments for navicular disease?
It is important to re-iterate the need for good balanced shoeing in these horses. Over 90% of cases will respond to this alone. Once this is achieved other therapies can be offered including the use of intra-articular injections into the coffin joint or navicular bursa, extra-corporeal shockwave therapy, and bisphosphonates e.g., Osphos.
To give an example; a 10-year-old Warmblood gelding presented with bilateral (both) forelimb lameness that blocked to the heel region. Radiographs of the front feet show that the external hoof balance is good but based on the radiographs some minor modifications were needed. There was minor sclerosis of the distal border of the navicular bone. In addition to the shoeing recommendations, the horse was given a single injection into the coffin joint since medications delivered here also diffuse into the navicular region. A short course of oral firocoxib (Equioxx) was prescribed for 14 days. Since on the radiographs the horse had some bone remodeling, we followed up with Osphos every 6 months to reduce bone resorption and modeling over the long term.