Burning sage -- or smudging -- is a traditional Native America ritual to protect against hostile energies. The smoke from burning sage is not more harmful than burning a candle or incense, but cats with respiratory conditions may find the smoke irritating. You also need to be wary of a curious cat singing its paws or batting burning sage out of its container.
Like humans, animals may or may not benefit from the spiritual practice of smudging. If you feel smudging may benefit your cat, hissing, scratching and urinating outside the litter box may be signs that it's time to change energy in the home with smudging.
Sage is burned loose in a fireproof bowl or tied in a bundle. Ignite the sage then blow it out to release its incensed smoke. If doing a smudging ceremony, you'll open windows and doors to let negative energy out as the sage's negative ions uplift the mood in the room. When burning sage for the good smell alone, keep in mind that without circulation such as an open windo, polycyclic aromatic hydrocarbons -- chemicals that are harmful to health -- can rise to levels similar to those in the home of a smoker. This can result in cats suffering respiratory irritation, especially if they have pre-existing conditions such as asthma or bronchitis. If your cat starts to sneeze or has watery eyes, it's best to move the cat to another well-ventilated room when you are burning sage. If you keep your cat in the room with you, keep a careful eye on the sage to make sure your cat's curiosity doesn't result in singed paws or hot embers getting knocked out of the burn bowl.
Sage is nontoxic to cats, so don't worry if your kitty nibbles a few leaves while you're setting up. Once you light it up, supervise your cat to prevent her curiosity from resulting in a burned paw or hot embers spilling onto furniture or flooring.