[header] How to give your cat a joint supplement [title] Determine if your cat needs a supplement. [step] It is okay, and probably even best, to give your cat a joint supplement before they show signs of pain or arthritis. Supplements will keep your cat's joints healthy and help slow the process of deterioration as they age. 
If your cat is showing signs of arthritis and you haven't been giving them supplements, keep in mind that they take about four to six weeks to work and increase your cat's mobility. Signs of arthritis can be difficult to spot since arthritis shows itself differently in cats.