The purr has "healing power", however, you can't replace pain killer and casts with a cat's purr. According to recent "research on frequencies that promote bone growth, fracture healing, pain relief, and relief of breathlessness and inflammation," frequencies between 20 and 150 Hertz are healing frequencies. Except for the cheetah, all cat species have purr frequencies ranging from 20 to 150 Hertz." The cheetah purrs at frequencies of 25, 50, 100, 125, and 150 Hertz. "This exactly corresponds with the best healing frequencies."
Lyons observes that a cat's purring reduces tension – caressing a purring cat has a relaxing effect. It alleviates the symptoms of dyspnoea (breathing trouble) in both cats and people. It also decreases blood pressure and the risk of heart disease. Cat owners are 40% less likely to suffer a heart attack.
Cat purrs are said to assist with infections, swelling, and discomfort, muscle development and repair, tendon repair, and joint mobility.
https://ryortho.com/breaking/is-there-healing-power-in-a-cats-purr/