A diagnosis of navicular disease can be devastating to the horse owner. I know, because I heard that diagnosis from my veterinarian about my beloved horse, Bo. As a result of having to treat my horse for this disease I have done a lot of research on it. Here is some of what I have learned.
Navicular disease is a degenerative disease of the navicular bone in the horse’s hoof; as the deep flexor tendon rubs over the degenerating bone it causes inflammation and lameness in the horse. This is sometimes referred to as navicular syndrome because it affects other structures in the same region as the navicular bone and it can be difficult to determine what is causing the inflammation. This disease does not affect only older horses; it can begin to cause lameness as early as age three. Although no one knows what causes it, there seems to be a genetic component that affects the anatomy of the foot which can be aggravated by either poor shoeing or lots of stress like a performance horse might experience. At this time there is no cure for this disease, but there are treatments for the pain and inflammation.
If the horse is often lame on the front feet where no other cause, like an abscess or stone bruise, is apparent, navicular disease might be a cause. The horse may attempt to alleviate the pain by trying to walk primarily on his toes, so he may stumble as a result. You will not be able to diagnose the horse yourself, but these are signs that you should consult your veterinarian. The vet will observe how the horse moves and test the hoof for sensitivity to pressure. If the horse has more pain in the heel the vet will do a nerve block of just the heel. Then the horse will be tested again to see if the nerve block has stopped the pain. If the horse no longer limps after the nerve block that is an indicator that the horse may have navicular disease. The only way to be sure is by either x-rays or an MRI. An x-ray may show changes in the navicular bone that are consistent with the disease; dark channels will show on the radiograph where the bone is breaking down.
The first step your vet will probably recommend is corrective shoeing and temporary treatment with Bute or another NSAID. Shoeing changes will include shortening the toes and rolling the shoes so the break over point is moved back. The shoes will also be extended further back behind the heel of the hoof to give it more support. The vet may also recommend egg bar or D-bar shoes because they are closed at the heel and provide more support. Also the angle of the hoof may be changed so the heel is elevated a little which will take some of the pressure of the deep flexor tendon off the bone. There is an element of trial and error to get the angles and the type of shoe just right and you may have to shoe the horse more often to keep the toes from growing too long.
Corrective shoeing may be all the horse needs to begin to feel better. A change in the horse’s activity level may also be required if that activity puts too much pressure on the affected areas of the foot.
Some supplements have been shown to ease pain of horses with navicular disease. A 2001 study showed that horses with navicular pain were helped after taking Cosequin for two months. I tried this supplement with my horse but it did not have a significant effect.
Two other supplements, Devil’s Claw and Duralactin, have good anecdotal evidence that they relieve Navicular and joint pain in horses. Duralactin is the more expensive of the two. I am trying both supplements on my horse and I will write another article in the coming months to report on my experience.
If other treatments are not working, the veterinarian may inject steroids and other medicines like Legend, directly into the navicular bursa, the fluid filled sac that protects the bone from the tendon. The horse usually feels better within a week of the injection and it may control the inflammation for up to a year. This treatment stops the inflammation but does not stop the degeneration of the bone, so as the disease progresses it will be less effective.
Another treatment uses an osteoporosis drug, Tildren; this drug has the potential to stop the bone degeneration. This treatment is used mostly in Europe but some veterinarians are using it in the U.S. as well. This treatment involves an IV drip of the medicine, so it must be done by the vet. The drug is expensive and must be repeated periodically so this treatment will be costly. Results from this treatment have been promising, but its long term effectiveness is unknown.
Another option is to “Nerve” the horse, which is to cut the nerve that goes to the heel of the foot. This procedure just numbs the affected area so the horse feels no pain; it does nothing to stop the breakdown of the bone. Because the horse cannot feel pain he could make an injury worse by continuing his usual activity and there will be no behavioral signal to the owner that the horse is injured.
Research on New Treatments
A very recent paper reports on another surgical treatment, core decompression, that is being studied. The veterinarian drills small holes in the navicluar bone, this relieves pressure in the bone and stimulates new bone growth. This type of procedure has shown promise in treating people with bone degenerative diseases. This study was done only to determine the feasibility of doing this in horses, and whether it would result in lower bone pressure and stimulate new bone growth. In this sense the study was successful. Now it must be tried in horses with navicular disease to evaluate its effectiveness.
It may seem hopeless when your horse has this disease, it is difficult to treat, but there are a number of things that can be done to make your horse feel better, it’s a matter of trial and error to find the right solution for each individual horse. For now do what you can to keep your horse comfortable and keep looking for new solutions.
Hanson, R. Reid, et al. Oral treatment with a neutraceutical (Cosequin) for ameliorating signs of navicular syndrome in horses. Veterinary Therapeutics. Vol. 2, 148-159. 2001.
Jenner, Florien and Kirker-Head, Carl. Core decompression of the equine navicular bone: An in vivo study in healthy horses. Veterinary Surgery. Vol. 40, 151-162. 2011.
Kamm, Lacy, et al. A review of the efficacy of Tiludronate in the horse. Journal of equine veterinary science. Vol. 28, 209-214. 2008.