1. A method for preventing and treating osteoarthritis in an animal, comprising administering to the animal a therapeutically effective amount of DGLA. 2. The method according to claim 1, wherein DGLA is administered in an amount of from about 0.01 to about 100 mg / kg / day. The method of claim 1, wherein DGLA is administered to the animal on an ongoing basis. The method of claim 1, wherein the animal suffers from osteoarthritis. The method of claim 1, wherein the DGLA is administered as a dietary supplement or food composition. The method of claim 5, wherein the composition is a food composition and the DGLA comprises from about 0.001 to about 40% of the food composition. The method of claim 5, wherein the composition or dietary supplement further comprises one or more probiotics； inactivated probiotics； components of inactivated probiotics that stimulate health benefits similar or the same as probiotics； and one or more prebiotics. 8. The method of claim 1, wherein the animal is a human or companion animal. The method of claim 8, wherein the companion animal is a dog. The method of claim 8, wherein the companion animal is a cat. The method of claim 1, wherein the animal is an old animal. A method for preventing and treating articular cartilage degradation in an animal, comprising administering to the animal a therapeutically effective amount of DGLA. The method of claim 12, wherein the DGLA is administered in an amount of from about 0.01 to about 100 mg / kg / day. The method of claim 12, wherein the DGLA is administered to the animal on an ongoing basis. The method of claim 12, wherein the animal suffers from degradation of articular cartilage. The method of claim 12, wherein the DGLA is administered as a dietary supplement or food composition. The method of claim 16, wherein1. Способ предотвращения и лечения остеоартрита у животного, включающий введение животному терапевтически эффективного количества DGLA.2. Способ по п.1, в котором DGLA вводят в количестве от
