Dimethylsulfoxide (DMSO), a byproduct of the chemical solvent industry, was approved by the FDA to treat musculoskeletal disorders in horses and dogs more than 30 years ago.
However, many veterinarians argue that DMSO produces exactly the opposite effect you want when treating a recent injury. Initial treatment for bumps and traumas that are hot and swollen to the touch is cold therapy; hosing a swollen joint or ligament with cold water and icing the area is standard primary emergency care. Putting DMSO on a “fresh” injury increases the heat in that area and can actually increase inflammation.
Always wear rubber gloves when using DMSO, since it is rapidly absorbed by deep tissues—in humans and horses alike. This rapid absorption can be beneficial, especially when DMSO is mixed with other veterinarian-approved topical substances—like antibiotics and anti-inflammatory drugs.
Always check with your vet before using DMSO—mixing the solvent with some substances can be very dangerous. Also, DMSO acts as a carrier agent, so anything on your horse’s skin (i.e. dirt and bacteria) will also be carried into the bloodstream.
DMSO can be irritating to horses, and some will stamp their feet and even rub and chew treated areas. DMSO should not be used on an open wound.