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Dimethyl Sulfoxide, DMSO

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DMSO (dimethyl sulfoxide) is a clear, odorless liquid made from wood pulp. It has been used since the 1950’s as an industrial solvent. 

It was first used medically in the early 1960s. Since then, DMSO has been hailed as everything from a miracle drug to a cancer causing toxin. It has been used sporadically in human medicine. Some MDs have touted the amazing effects of DMSO, but it has never been widely accepted. DMSO is only FDA approved for human use as a tissue transplant preservative and for the treatment of one type of bladder inflammation (cystitis). It is FDA approved for horses as a topical medication.

HOW IT WORKS

DMSO has many interesting and rare properties. Most importantly, DMSO is a non-steroidal anti-inflammatory drug (NSAID), and it has a molecular structure which allows it to penetrate through skin and cell membranes into the bloodstream without causing damage.

DMSO has antioxidant properties that are considered anti-inflammatory. It is considered a powerful free radical scavenger. DMSO has some antibacterial action. It slows the multiplication of bacteria but does not kill them. DMSO may provide some short term pain relief, either through reduction in inflammation or direct pain relief.  DMSO is a diuretic, and so results in increased urine production.

VET’S ROLE

For bruises, strained muscles and soft tissue injuries, vets frequently use DMSO solution or gel topically for its direct anti-inflammatory effect and tissue penetration. DMSO can also be mixed with steroids, antibiotics and antifungals to try to get them to penetrate more deeply into the tissues to sites of injury or infection.

DMSO can be safely used topically for a number of conditions. DMSO can be used as a poultice alone, or with other medications. It draws water (swelling) out of tissues. It is often used in sweat wraps and topically to reduce swelling and pain at the injury site.

DMSO is also mixed in intravenous fluids, or mixed with water and administered orally through a stomach tube to treat these conditions:

– Treatment of brain and spinal cord injury and inflammation.  

– Treatment of horses with laminitis (hard to quantify the results). 

– Treatment in post-colic surgery endotoxemia to protect tissues from inflammation and free-radical damage.

– Treatment of arthritis, as it may help reduce inflammation and pain.

– As a diuretic, in cases where there is excessive fluid that needs to be removed from the body, such as pulmonary (lung) edema.

YOUR ROLE

Horses treated with topical DMSO need to be monitored for local irritation. Horses that have been given oral or intravenous DMSO should be watched for side effects.

Consider Potential Side Effects & Complications

Thick rubber gloves should ALWAYS be worn when handling DMSO due to its unique ability to penetrate through skin.  It will penetrate thin latex gloves and can eventually dissolve them. 

Horses treated with DMSO in intravenous fluids or by nasogastrc tube can rarely have adverse reactions, including but not limited to diarrhea, colic, tremors and seizures. Given at high concentrations in intravenous fluids, DMSO may cause hemolysis - the breakage of red blood cells.

DMSO's diuretic qualities can result in further dehydration and lower blood pressure in a horse that is already dehydrated or in shock.

Applied topically, DMSO can cause local reddening and irritation. Some horses tolerate it well while others do not.

Mixing DMSO with fly sprays, OTC wound medications or other topical liniments can cause absorption of those chemicals into the blood stream. Depending on the chemical and dose, this can result in toxicity.

When mixed with water DMSO becomes hot, and care should be taken to avoid injury.

Be careful of using DMSO in competition horses. It may carry topical medications into the blood and result in a positive drug test.

It is important to apply DMSO to clean skin as there is a chance it can carry skin contaminants into the deeper tissues. However, DMSO probably does not help carry bacteria or viruses into tissues.

Consider Reasons Not To Use This Treatment

DMSO freezes solid at about 50 degrees F, so it cannot be used in the field during cold weather.

DMSO should not be given to very dehydrated horses because of its diuretic action and tendency to worsen dehydration.

Do not use DMSO topically in horses that have demonstrated a sensitivity to it such as pain, or reddening of skin.

Is It working? Timeframe for effect

Improvement in pain and swelling (anti-inflammatory effects) are noticeable in hours.

In cases where the brain and spinal cord trauma are treated, it can be difficult to isolate the effects of DMSO from other treatments, but my impression is that there is noticeable improvement within hours.

Author: Doug Thal DVM Dipl. ABVP

RELATED REFERENCES

Gorog P, Kovacs JB. Antiarthritic & antithrombotic effects of topically applied dimethyl sulfoxide. Ann NY Acad Sci 1975;243:91.McIlwraith C.W. Frisbie DF, Kawcak C. Current Treatments for Traumatic Synovitis, Capsulitis & Osteoarthritis. AAEP Proceedings 2001 V.47 P.180.Swanson BN. Medical use of dimethyl sulfoxide (DMSO). Rev Clin Basic Pharm. 1985 Jan-Jun;5(1-2):1-33.

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