Spice Up Your Pain Relief

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Whether it’s acute pain from a recent injury or nagging chronic problem, when your horse hurts, you want to help. Sometimes you need to contact your veterinarian to get a firm diagnosis and/or a prescription drug, but many times you know you don’t need that strong an approach.

You want something like what a person with arthritic joints uses for a pain-relieving rub. But similar products for horses can be pricey, and you wonder if they really work. More importantly, you may wonder if there are drawbacks or side effects to the products. So did we.

Rub-On Pain Relief
We’re all familiar with traditional rubs and liniments that are heavy on menthol, camphor and aromatic oils. They all work by counter irritation on the skin and create:

• A mild local inflammation that encourages blood flow.
• Soothing sensations/perceptions.

These irritants activate specific nerve endings responsible for the perception of heat and cold. The skin “thinks” it’s experiencing cold when in reality the effect is mildly irritating and warming. Recent research shows that the initial cool feeling is caused by menthol chemically activating cold receptors on nerve endings. As the irritant effect heats up, the sensation changes to warmth.

There’s a fine line between what the horse’s nervous system detects as warmth, cold, pressure or friction and what causes it to trigger pain. Since the nerve endings for pain usually contain a mixture of hot and cold receptors, as well as actual pain receptors, ingredients that keep these nerves busy with sensations of heat or cold will “distract” them from feeling pain. This is also the mechanism by which hot or cold packs relieve pain.

Unfortunately, the horse’s skin isn’t as forgiving of the irritant effects of traditional menthol or camphor as human skin, and prolonged use can cause swelling, scaling and even damage to the skin with cracking. A pain-rub product that we may perceive as soothing may make a horse agitated and uncomfortable. Instead, modern pain-relieving topical products often contain less-familiar ingredients, including:

• Capsaicin: Capsaicin is the chemical responsible for the hot sensation from chili peppers. It binds to receptors on sensory nerves and causes the release of a chemical called substance P, which stands for pain.

When high concentrations of substance P are applied to the skin, the result is an intense burning pain. At lower concentrations, lower amounts of substance P are released and warmth/heat is detected. Capsaicin also blocks the re-uptake of substance P by the cells releasing it. The result is that with continued use the local supplies of substance P become depleted and pain is blocked. Capsaicin is well absorbed through skin. Note: You may also hear the term “capsicum,” which is the botanical name of the hot pepper. Capsaicin is the name of the active chemical in the pepper.

• MSM and DMSO: Although the exact details of how MSM and DMSO work aren’t clear, both do have anti-inflammatory effects. DMSO blocks free-radical production, preventing inflammatory reactions in this way. MSM may work the same way. However, DMSO is well absorbed through the skin, while MSM’s absorption through the skin hasn’t been well documented. MSM is usually given as a dietary supplement.

• Glucosamine and chondroitin: We’re all familiar with feeding glucosamine and chondroitin, but now manufacturers also suggest we rub it on. Justification for this use probably traces back to European studies that showed improvement in active inflammation in arthritis patients and with sport injuries when a combination of heparin and a heparin-like compound, were applied. Both are members of the glycosaminoglycans (GAG) family, as is glucosamine. Glucosamine is a simple compound compared to these compounds and could be absorbed, although it’s not documented that it is. Nor is it documented that if it is absorbs it has an effect. Chondroitin is a much more complex molecule, also with no documented effects.

• Benzocaine: Benzocaine is a widely used local anesthetic drug.

Field Trials
When we first tried a capsaicin product in July 1995, we found it caused so much skin irritation the drawback outweighed any benefits. Fortunately, the formulas have been toned down since then, with soothing aloe and chamomile bases added, resulting in a new generation of well-tolerated capsaicin creams.

We found no reactions with capsaicin products on normal areas. When we used them over hot, swollen and inflamed areas, about half the horses showed some stomping or resistance. However, that response was both less dramatic and less frequent than what we observed with DMSO. Some initial mild-to-moderate skin reaction in the form or puffiness and heat was noted in several horses after application of topical products containing capsaicins. However, in every case, we noted improvement in flexion tests and degree of lameness despite this reaction. Overall, we found capsaicin lotions less effective than the cream products. As with all products, discontinue use if irritation develops.

We had high hopes for topical MSM, knowing what MSM supplementation can do for joint and muscle pain. Unfortunately, we couldn’t see any significant improvement in pain, swelling or heat. DMSO, on the other hand, was rapidly effective in reducing swelling and heat over areas of acute inflammation and offered fair-to-good pain relief.

We found neither topical MSM nor topical DMSO made any demonstrable difference in lameness when used on joints or tendons that were not acutely inflamed or when applied to sore muscles. Thermaflex, which contains MSM and menthol, was irritating to our users and horses, so we suggest users wear gloves and avoid getting on your skin or eyes.

We also weren’t impressed with the chondroitin and/or glucosamine products. None showed detectably different effects from a plain camphorated rub. We also had skin reactions that occurred in a range of within a few minutes to after three to four days of continuous use.

We had one benzocaine-containing product: EPF-5. Its other active ingredients in the base include menthol, thymol and various mineral salts. It was about as effective as plain camphorated rubs on degree of lameness, but without the “dancing” commonly seen in horses after applying camphorated rubs. We suspect the benzocaine probably blocks this sensation. This product was more effective than other camphor-based products in reducing edema, which is probably due to its mineral salts. Use of this product may result in a positive drug test, however.

Bottom Line
Overall, we found capsaicin creams offered the most obvious pain relief, making them our choice for joints, tendons or ligaments. They were all worked similarly, but our favorite products were Activex Peformance Topical Pain Reliever, Capsa-Cream and Sure Block. Let price be your guide. If you prefer a lotion, we like Vapco Bloc-It.

For back-muscle pain, we’d go with EPF-5. The pain relief was comparable to other camphorated muscle products but with less of an irritant effect. Pain in larger muscle groups didn’t respond well to topicals.

For swelling, we liked generic DMSO and EPF-5 best.

Also With This Article
Click here to view ”Smart Topical Pain Reliever Use.”
Click here to view ”Response To Topical Pain Relievers.”
Click here to view ”Judging Pain Relief.”
Click here to view ”Topical Pain-Relieving Products.”
Click here to view ”Capsaicin and Feet.”

Contact Your Local Tack Store Or: Brock Animal Health 888/848-3343; Uckele Health and Nutrition, www.uckele.com 800/248-0330; Jack’s Mfg. www.jacksmfg.com 740/335-5121; EquiFlite Technologies Inc. www.donalex.com 800/595-7223; Grand Meadows, www.grandmeadows.com 714/628-1690; Smart Science Laboratories 888/464-3336; Vita-Flex www.vita-flex.com 800/848-2359;Farnam www.farman.com 800/234-2269; Garmon Co. www.vapco.com 800/523-5614.