Texas Equine Veterinary Association

www.teva-online.org • Page 18 are generally regarded as more efficacious. Corticosteroids are typically regarded as those that are cartilage sparing, quicker to act, but weaker in intensity (triamcinolone) or those that have a profound response that are slower to act and may be detrimental if used in excess to the cartilage (methylprednisolone). Recent studies have indicated that the use of HA alone in navicular bursal injections have an insignificant therapeutic response. In the same study, using less than 10mg of triamcinolone had worse therapeutic responses when compared to groups administered HA alone. Some feel, however, HA can be beneficial in cases with adhesions where distention of the bursa may break them down. The author uses a combination of HA, triamcinolone and methylprednisolone in warranted cases. He also holds to a general rule of thumb to not inject the bursa more than two times in a year as constant DDFT penetration may be detrimental. In regards to the DIPJ, the author will use differing combinations of HA and triamcinolone. Adequan has recently been questioned as to its efficacy intrasynovial, but we will often use it in cases where we feel or know there is a compromised cartilage bed and have been satisfied with its results. The author holds to a general rule of thumb to not inject the DIPJ more than three-four times a year, if possible. IRAP has become a common joint therapy in recent years and can be used in cases that may require more frequent anti-inflammatory action without the negative side effects of corticosteroids. Special processing equipment (proper centrifuge and incubator) are required for its use, but multiple doses—usually four-six aliquots—can be retrieved from one draw. IRAP may work in alternate pathways when compared to corticosteroids and its therapeutic benefits appear to have a cyclical timeline. The author frequently uses IRAP in high motion joints that require management but feels its benefit may be less rewarding at the DIPJ because palmar foot pain is often from soft tissue structures and not just the joint. Promising therapeutic options for soft tissue injuries have been introduced to the equine practitioner over the last several years. A number of these options have become especially popular, but successful therapy will likely be complex and many years down the road. Combinations of different aspects of tissue regeneration are likely to produce the best results and include: those which provide a scaffolding on which tissue repair may organize, a source of precursor cells that can differentiate into the appropriate soft tissue, and a physiologic combination of growth factors and cytokines that stimulate the process. Two common options are the use of stem cells, whether marrow or adipose derived, and platelet- rich plasma (PRP). The author will use stem cells in cases with larger core lesions and reserves PRP for cases of desmitis or tendonitis with smaller core defects. Adipose derived stem cells are easier to harvest but recent studies show bone marrow derived cells may provide a better mix of matrix products and a greater number of progenitor cells. PRP is, essentially, the area of intense platelets at the level of the buffy coat in centrifuged blood. It has shown promising results in some cases of suspensory desmitis and can be used in the tendinous or ligamentous areas of the palmar foot. Recently practitioners are freezing the sample prior to use to destroy any leukocytes that may inhibit the therapeutic activity of the PRP. Kits that separate the blood and allow for aliquot retrieval can be purchased and require only the proper centrifugation for use. The lesions can then be treated with the desired product by identification on ultrasound or triangulated with radiographs as in the case of distal DDFT pathology. Spinal needles may be required to deposit the aliquot in its desired location. Tiludronate, trade name "Tildren", is currently under investigation to determine its efficacy in the treatment of navicular disease. The active drug is in the biphosphonate class of drugs used in human medicine to inhibit bone resorption in disease like osteoporosis. Its mechanism of action is the inhibition of osteoclastic activity in areas of intense bone remodeling like osteolysis or osteoarthritis. By reducing the resorption of bone, Tildren's action may be of benefit in cases where palmar foot pain is specific to the navicular bone. The duration of action of the drug is weeks to months, as it is slowly eliminated once bound to hydroxyapatite crystals at the sites of active bone remodeling. Some practitioners feel that clinically there may be an anti-inflammatory component to it. Treatment consists of administration through diluted IV fluids over a minimum of 30 minutes. Transient hypocalcemia can occur and patients should be withheld from feed and given flunixin meglumine as a precaution for colic. The author has used the product as labeled and in regional perfusions in multiple cases, but its efficacy is still up for debate. Patient selection is important as cases with soft tissue lesions may or may not respond favorably. Its use is promising, but empirical literature to substantiate its mechanism of action and benefits is needed. Another bisphosphonate that just recently received FDA approval for treating navicular disease is Clodronate, trade name "OsPhos." This drug is administered intramuscularly and is marketed by Dechra. Prognosis regarding each of these treatments is highly dependent on what lesions are actually present. Bursitis, synovitis, and capsulitis of synovial structures without underlying cartilage or fibrocartilage defects will likely respond well to injections. Bone pathology will likely be dependent on its severity and effect on surrounding soft tissues. The use of Tildren in horses non- responsive to conventional therapy and used as the sole treatment in horses with navicular disease and bone spavin was 60% successful in follow up examinations at six months. However, more research is needed to confirm its clinical benefit. Soft tissue injuries follow a similar prognosis as those lesions found elsewhere in the limb. Four to six months may be required to repair the histoarchitecture of the tendon fibers, but the use of stem cells, PRP, and other autologous modifiers may hasten that timeframe and improve fiber patterns and lameness quicker. Once again, a proper identification of the pathology will allow the practitioner to develop a better rehabilitation protocol and offer a more realistic prognosis. Approaching palmar foot pain can be challenging. It is one area where a profession and trade must work together on an area that is poorly visualized, frequently plagued, hard to treat, and limited in its therapeutic options. It is no wonder we have redefined the problem and have so many conflicting ideas regarding therapy. Focusing on developing a mechanical shoeing prescription based on the alterations of leverage, tension, pressure, and protection, and accurately diagnosing the severity, with improving diagnostics, is a start in the right direction. Utilizing MRI and specifically designing our treatment based on whether it is joint, soft tissue, or bone will further improve the ability to manage palmar foot pain. Submitted by TEVA Member: Britt Conklin, DVM, CF Boehringer-Ingelheim

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