Category Archives: Lameness

Navicular Syndrome (Caudal Heel Pain)

Horse owners dread the diagnosis of navicular syndrome. Much new research has focused on this disease. To help understand whether there is a cause for concern, this month’s blog post will help clear up some myths and illuminate the facts surrounding this disease.

The most common sign of this syndrome is lameness. Sometimes there is an obvious lameness in one limb or, when both front limbs are affected, a general shortening of the stride. The front limbs are the most commonly affected.

To diagnose this disease, our veterinarians will observe the horse’s gait in-hand in a straight line and on circles, often on different footings, and sometimes under saddle. Careful palpation of the limb, hoof testers (metal instruments used to squeeze on the hoof) and flexion tests are also used to localize the lameness. When diagnosing any lameness, nerve blocks (numbing the nerve that innervates a particular region) provide our veterinarians with more conclusive evidence to localize the pain of lameness. Horses with navicular syndrome will improve when their heel is numbed.

health-hoof

http://localriding.com/navicular-in-horses.html

We can’t talk about this disease without discussing anatomy. Navicular syndrome refers to pain coming from the heel region. Hence, the technical term for this disease is caudal (scientific term for towards the tail) heel pain. There are many important structures in the heel region that can contribute to this disease. The navicular bone is a small boat shaped bone (“navicu” means small boat in Latin) and has a small fluid filled pocket, the navicular bursa, which provides lubrication for the deep digital flexor tendon to glide over the bone. The deep digital flexor tendon runs down the back of the horse’s leg, around the navicular bone, and inserts on the largest bone in the horse’s hoof, the coffin bone. The navicular bone also has several ligaments that hold it in place. Any inflammation, tears, or scar tissue to these tendons, ligaments, or bursa can cause heel pain. Changes to the navicular bone – spurs, bruising, fractures, damage to the cartilage, or holes in the bone also cause pain. Long term prognosis is depends on which structure is affected.

Navicular disease used to be attributed to bony changes in the navicular bone seen on radiographs. Now we know many of the soft tissue structures in the heel can cause the pain of this disease and the name has changed from “disease” to “syndrome.” As with any therapy, treatment is most successful when we know exactly what structure is painful. The challenge with navicular syndrome is determining which structure is painful. This area is located in the hoof capsule and difficult to image. Changes to the bone can be visible on radiographs, but the only way to visualize the many soft tissue structures is with ultrasound (fairly inaccurate) or MRI.  MRI is the best modality to image this area, but is expensive and requires general anesthesia for the best images.

One type of therapeutic shoe. Note the rounded shape of this rocker shoe.

One type of therapeutic shoe. Note the rounded shape of this rocker shoe.

Treatment is based on the source of pain. The most common treatment is shoeing changes, which are based on the horse’s conformation and radiographs. It can take up to two weeks to see the full effect of any new shoes, so be patient. Sometimes anti-inflammatories, such as bute, are also used, though if you are showing, be aware of USEF rules. Injecting anti-inflammatories (steroids) directly into an inflamed navicular bursa or the coffin joint (a nearby joint) also affords relief to some horses. Bisphosphonates (Osphos and Tildren) are a class of drugs that alter bone metabolism and are also used for some types of navicular syndrome. For horses with chronic pain, a surgical procedure where the nerves that innervate the heel are severed, may be recommended. This procedure is also known as “nerving”. This isn’t a permanent solution – the nerves may grow back, and requires daily monitoring to make sure there isn’t a wound on the now numb heel region.

Quarter horses, thoroughbreds and warmbloods are the mostly common affected breeds, but any horse with a long toe/ low heel, disproportionally small feet, contracted or sheared heels conformation is also predisposed.

There are some horses that navicular syndrome is athletic career ending, but with the right management, many horses perform for a long time with this disease. If you think your horse might have navicular syndrome or have any questions, please contact us.

 

Chiropractic for Horses

The word chiropractic is derived from the Greek words “cheir” meaning “hand” and praktike” meaning “business or to practice”.  Chiropractic focuses primarily on the relationship of the vertebral column and the nervous system, and how that relationship affects the preservation and restoration of health.  A chiropractic adjustment is a very specific high-velocity, low force controlled thrust by a hand which is directed in a specific direction on a specific joint.  This restores the full range of mobility and neurological function.

COLTS HEAD26Horses have a high prevalence of neck and back problems which can be presented as a lameness, stiffness, lack of impulsion, poor mental attitude, gait abnormalities, cold-backed, cinchy or unwillingness to perform.  Limb lameness, poor saddle fit, rider’s ability, conformation or shoeing affects changes in body carriage which can cause body pain.  Chiropractic manipulation of the spine and associated musculature can resolve the pain and reduce mobility in the joints and associated muscles.  Chiropractic is not a “cure all” for all neck / body problems and is contra-indicated for fractures, infections, cancers and non-mechanical joint problems.  It will not reverse degenerative joint disease (arthritis).

COLTS HEAD25An initial chiropractic evaluation involves an oral exam, saddle fit, gait and shoeing evaluation, acupuncture sensitivity and range of motion in the vertebral segments.  It takes forty-five minutes to an hour and is not painful to the horse.

Osteoarthritis Treatments Part II: Systemic and Intra – Articular Therapies

Earlier this fall, we discussed how non-steroidal anti-inflammatory drugs and joint supplements can improve comfort.  This month, we will discuss how systemic therapies, such as Adequan, Legend, and Pentosan, and intra-articular medications help arthritic joints, as well as some future therapies.

Systemic Therapies (Adequan, Legend, and Pentosan)

The next step in treating osteoarthritis is often a systemic therapy.  Systemic therapies are administered either intravenously or intramuscularly and have the advantage of treating multiple affected joints.  They often have more affect than oral joint supplements, but are not as good at relieving pain as the NSAIDs or joint injections.  These products do have the advantage of modifying the progression of the disease process and are often used as general maintenance for cartilage health.

Hyaluronan (HA) (Legend), polysulfated glycosaminoglycans (PSGAGs) (Adequan), and pentosan polysulfate (Pentosan) all have different mechanisms of improving cartilage health.  In our experience, HA has more of an effect when administered directly into the joint, as opposed to the intravenous form (Legend).  However, a study did show Legend improved lameness in horses with arthritis.  Adequan has also had studies that prove effectiveness, and in our experience, has been beneficial in treating this disease.  Pentosan is a proven, but newer drug in this country.  Pentosan is available in the US as a compounded product, meaning it is made in small batches for specific patients and without the guarantee of a pharmaceutical company.  Pentosan has helped many of our patients.  Adequan has recently been on manufacturers’ backorder and our stock of this product has been limited.  Adequan is supposed to be back on the market soon.

injecting hock compresssed

Dr. McAndrews injecting one of the hock joints.

Intra-Articular Therapies (Joint Injections)

Intra-articular therapies deliver potent medications directly to the affected joint.  A combination of steroids, antibiotics, local anesthetic, and HA are most frequently administered.  Steroids have a strong anti-inflammatory effect and also have a disease modifying affect, significantly improving lameness in most affected horses.  Much has been studied about the deleterious affects of steroids in joints but at the low doses we use, the activity level of most horses, and the frequency of most injections, this adverse affect is minimal.

In some joints, HA is also administered for its effects in improving cartilage health.  A combination of HA and steroid can prolong the beneficial affect of the joint injection.  Adequan can also be administered intra-articularly to improve cartilage health.  Regenerative therapies, such as PRP and IRAP, are used intra-articularly to manage OA with some success.

Future Therapies

Bisphosphonates (Tildren) inhibit bone resorption and may help in diseases with increased bone turnover, such as OA.  This drug is already being used for the treatment of certain types of navicular syndrome and more studies are pending.

Tetracyclines such as doxycycline and minocycline, are antibiotics that have been found to have anti-inflammatory effects.  These antibiotics have been used to treat OA in humans.  Studies are underway to decrease the antibiotic properties of these drugs but keep the anti-inflammatory effect.

In summary, NSAIDs are often used for brief periods to manage short term pain, oral joint supplements can be of benefit in mild cases of OA, systemic medications help moderate cases and cases with multiple joints effected, and intra-articular medications have the most potent affect in improving lameness.

 

Osteoarthritis Treatments Part I: NSAIDs and Joint Supplements

compressedpicAt some point in many athletic horses’ career, they will develop osteoarthritis.  Osteoarthritis is inflammation in a joint that leads to cartilage damage and eventually bony changes.  The inflammation and resulting changes in the joint are painful, causing lameness or stiffness and sometimes heat, swelling, or extra fluid in the joint.  The most common joints affected by osteoarthritis are the lower joints of the hock, also known as bone spavin, but any joint can be affected.

Unfortunately, there is no cure for osteoarthritis.  Due to the chronicity of the disease, long term therapies are often required and can have side effects.  Treatments of OA are divided in two categories- treating just the signs of the disease (pain/ lameness) and treating the disease process.  Often a combination of therapies is used to get the best results. The ultimate goal is to prevent further progression of the disease while improving function and comfort of the affected joint(s).

For successful management of osteoarthritis, an accurate diagnosis is needed.  A complete lameness exam, performed by a veterinarian, is necessary to make this diagnosis.

There are many available therapies for OA and many make claims that seem too good to be true.  With this blog, we will sift through some available products and direct you to the ones with research behind them.  In part one, we will discuss non-steroidal anti-inflammatory drugs and joint supplements; part two will cover systemic and intra-articular therapies, as well as future directions in treatments.

Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)

Symptomatic treatments of this disease include non-steroidal anti-inflammatory drugs (NSAIDs).  The most common are phenylbutazone (bute) and firocoxib (Equioxx).  These drugs do a very good job of treating the pain and lameness associated with the disease and immediate results will be seen.  However, while the anti-inflammatory action does help with the inflammation caused by this disease, it does not address the underlying disease process.  Use of these drugs at competitions is also regulated by the FEI, USEF, and other horse show organizations.  These drugs are often used for a short period of time to improve flare-ups of the disease.  Long term use of these medications can have unwanted gastrointestinal (stomach and colon ulcers) and kidney side effects.

Oral Joint Supplements

The goal of oral joint supplements is to decrease the need or dose of other medications (and their side-effects) while slowing the progression of the disease.  Joint supplements are classified as nutraceuticals and are not regulated by the Food and Drug Administration.  There is no requirement to prove safety or efficacy.  Joint supplements vary tremendously in ingredients, amount of active ingredients, and consistency from batch to batch.  Even products with a “guaranteed analysis” on the package many not meet that label claim.  The products that have the most inconsistency tend to state they are a “complex,” formula,” or “blend” with no amount of each ingredient on the package.  Lot numbers and expiration dates also give some evidence that the product is reputable (but no guarantee).

However, many horse owners and trainers have noticed a response to treatment with these supplements.  The goal of these compounds is to provide the precursors for cartilage in excess so they are readily available if repair is needed.  Glucosamine and chondroitin, under the brand name Cosequin, is the only product that has undergone scientific testing.  In some studies, Cosequin did improve lameness.  Another study of glucosamine, chondroitin, and MSM combined showed some improvement in range of motion.  No scientific studies have found MSM, on its own, to improve the signs of OA.  Fatty acids have been beneficial in humans, but no published studies have proved efficacy in horses.  There are many herbal, vitamin, and mineral supplements purported to treat OA, though no studies have proven their effectiveness or safety.   Often, we recommend Cosequin or Cosequin ASU as a starting point for treating cases of mild osteoarthritis.  Other brands may also be effective, but keep in mind the lack of regulation and consistency with these products.  Your pocketbook will thank you!

Join us next month for our discussion of systemic and intra-articular therapies.