I heard of trainers putting meat tenderizer on the horses spur pressure areas why is that?

Meat tenderizer gets used in the spur pressure area of horses for two distinct purposes, and understanding the difference between them tells you a great deal about the horsemanship philosophy of the trainer doing it. One application is a legitimate skin care practice with a reasonable physiological basis. The other edges into ethically questionable territory and represents a shortcut that prioritizes the appearance of responsiveness over genuinely earned lightness. The legitimate use is for toughening and healing abraded skin in horses that have developed spur rubs — the raw, irritated patches that develop on the barrel where repeated spur contact has broken down the skin. Meat tenderizer contains papain, a proteolytic enzyme derived from papaya that breaks down damaged protein tissue and promotes healing in abraded areas. Applied to a spur rub, it can help clear away damaged surface tissue and allow healthier skin to form underneath, functioning similarly to the way it has been used by humans on insect stings and minor skin irritations for generations. Paired with a period of reduced spur contact and proper skin care, this use is defensible and has a clear benefit to the horse. The more problematic use is applying meat tenderizer to the spur area of a horse that does not have existing wounds — essentially treating sound skin with a proteolytic enzyme to artificially sensitize it and make the horse more reactive to spur pressure. The logic is that a horse with chemically sensitized skin will respond to lighter spur contact and appear more responsive and educated than he actually is. In the show pen or during a sale, that appearance of lightness and responsiveness can be genuinely deceptive. That second application is a welfare concern and an integrity problem simultaneously. A horse whose apparent responsiveness is chemically manufactured rather than trained is a horse whose buyer or new rider will discover very quickly that the lightness disappears when the sensitization wears off. It also represents a form of soring in spirit if not in the legal definition of the term. If you see a trainer applying meat tenderizer to the spur area of a horse with no visible skin damage, the question worth asking is which purpose it is serving — and the answer to that question is worth knowing before you trust that trainer with your horse.