Linum usitatissimum (also known as common flax or linseed), an annual herb believed to have originated in Egypt, is a member of the genus Linum in the family Linaceae. The seeds produce a fixed oil known as linseed oil or flaxseed oil. It is one of the oldest commercial oils and solvent-processed flaxseed oil has been used for centuries as a drying oil in painting and varnishing. The raw oil is used as an astringent in fungicidal lotion, insecticide and has shown moderate insect-repellent properties (The Wealth of India 2006). The oil contains unsaturated fatty acids like oleic acid (12–30%), linoleic acid (8–29%) and linolenic acid (35–67%) (The Wealth of India 1976). These fatty acids appear to render a drying property to the oil. In a preliminary study, Linum usitatissimum-fixed oil has been found to inhibit inflammation induced by carrageenan (Singh and Majumdar 1997). The therapeutic effect of L. usitatissimum fixed oil on acute and chronic arthritic albino rat models has been reported (Kaithwas and Majumdar 2010a). The antiulcer activity of L. usitatissimum oil in animal models has been reported recently (Kaithwas and Majumdar 2010b). Hydrolysed linseed oil possesses potentially useful antibacterial properties as a topical preparation. The hydrolysed lipid has been found to be effective against S. aureus resistant to antibiotics (McDonald et al. 1981).
Bovine mastitis is economically the most important disease at dairy farms and is usually caused by bacterial infections, eventually producing inflammation in the udder tissues (Yagi et al. 2002). Antibiotics are commonly used in the treatment of bovine mastitis. Considering the anti-inflammatory activity of linseed oil and antibacterial activity of hydrolysed oil, it was considered worthwhile to evaluate L. usitatissimum fixed oil for antimicrobial activity and therapeutic efficacy in bovine mastitis, an inflammatory disorder caused by microbial infection.