Sloan's Liniment (at right) was once a popular over-the-counter drug store item.
Liniment (or embrocation), from the Latin linere, to anoint, is a medicated topical preparation for application to the skin. Preparations of this type are also called balm. Liniments are of a similar viscosity to lotions (being significantly less viscous than an ointment or cream) but unlike a lotion a liniment is applied with friction; that is, a liniment is always rubbed in.
Liniments are typically sold to relieve pain and stiffness, such as from sore muscles or from arthritis. These liniments typically are formulated from alcohol, acetone, or similar quickly evaporating solvents and contain counterirritant aromatic chemical compounds such as methyl salicilate, benzoin resin, or capsaicin. Opodeldoc is a sort of liniment invented by the physician Paracelsus.
Uses on horses 
Liniments are a common substance used by trainers and owners of horses. They may be applied diluted or full-strength, usually added into a bucket of water when sponged on the body. Liniments are especially useful in hot weather to help a hot horse cool down: the alcohols help the product to quickly evaporate, and the oils they contain cause the capillaries in the skin to dilate, also increasing the cooling process.
Liniments should always be applied according to the manufacturer's directions, and diluted as necessary. Many horse owners apply liniments to the legs as a brace, and then wrap over it. In this case, they should be sure that the liniment is not too strong, or it may cause blistering of the skin.
Liniments may be used on the legs and body, but should not be applied to more sensitive areas such as the head, genitals or groin of the horse. The body may also be too sensitive to apply liniments if the horse was recently body-clipped.
Topical medication forms 
- Cream - Emulsion of oil and water in approximately equal proportions. Penetrates stratum corneum outer layer of skin well.
- Ointment - Combines oil (80%) and water (20%). Effective barrier against moisture loss.
- Gel - Liquefies upon contact with the skin.
- Paste - Combines three agents - oil, water, and powder; an ointment in which a powder is suspended.
References in Literature 
In John Steinbeck's Of Mice and Men, the Negro stable buck, Crooks, rubs it on his crooked spine to ease the pain. In Terry Pratchett's The Wee Free Men, local witch Granny Aching is known, among other things, for the liberal application of her home brewed Special Sheep Liniment. In Lucy Maud Montgomery's Anne of Green Gables, Anne accidentally bakes a cake with liniment as an ingredient.
See also