Natural - operating or occurring in a standard way; missing abnormalities or deficiencies; "it's the natural factor to occur"; "natural immunity"; "a grandparent's natural affection for your grandchild" When these membranes turn into inflamed, excessive immune cells and fluid accumulate In the joint spaces, leading to pain, swelling, and stiffness. https://rylanpflqv.bloginder.com/36636538/the-smart-trick-of-pet-pain-relief-that-nobody-is-discussing