Collagen is the main structural protein found in skin and connective tissues, joints, tendons, cartilage and ligaments. In fact, 30% of the total protein in your horse's body is collagen. Collagen protein determines the health and vitality of your horse's muscles, bones, gut nails, teeth, skin and coat. As animals age, their capacity to produce collagen diminishes and the visible and degenerative signs of ageing start to appear — making them more susceptible to injury, joint pain, mobility issues, poor digestion and skin allergies