What is the purpose of an undercoat in a Jack Russell Terrier?

An undercoat in a Jack Russell Terrier primarily serves to protect the dog from wet and cold elements. This dense layer of fur acts as an insulating barrier, helping to keep the dog warm in cooler temperatures and shielding it from moisture. The undercoat traps air close to the skin, providing insulation that helps regulate body temperature.

While insulation against heat is important, the primary function of the undercoat is more about retaining warmth and protecting against cold and wet conditions. The aesthetic appearance and concerns about shedding are secondary factors related to the coat but do not capture the primary purpose of the undercoat itself.