? She doesn't seem to be in pain but often holds that leg up while walking or sitting.
From the Animal Desk Reference by Melissa Shelton DVM p.331
Cat with Arthritis
Pet cat with Copaiba on hands: This method is well tolerated by cats and seems to be far superior to dripping oils directly on the skin. Due to the fact that hair follicles may enhance absorption, spreading the essential oils over a larger area of the cat may indeed prove more effective. Place the undiluted essential oil of choice on your hand, circle your hands together then pet your cat. You need to determine how much you let the oil absorb into your skin before petting your cat.
Litteroma: Use unscented litter. Add 1-3 drops of chosen essential oil (Copaiba for arthritis) to 1 cup baking soda, and store this mixture in a glass jar, allowing it to "marinade" overnight. Shake the mixture several times. You can add more essential oils if desired. Sprinkle a small portion onto the kitty litter and mix well. Provide a second litter box without the essential oil to make sure that your cat does not have an aversion to the essential oil selected. Once you are sure your cat is using the litter box with your essential oil selection and concentration, you can then omit the use of the "plain" litter box. Shelton mentions that people add Copaiba for arthritic issues, Digestion Support for intestinal upset and Frankincense for cancer.
There are warnings about using essential oils around cats. Melissa Shelton writes from her personal experience on pages 321-322:
"After hearing all of the concerns and warnings from the veterinary community, I had concerns for my own multi-cat household. Routine blood and urine evaluations calmed the concerns, and no detrimental effects have ever been shown with over 3 years of almost constant diffusion in my home. What I eventually found to be true, was that veterinarians who were so carefully warning other veterinarians and owners not to use essential oils, had in fact, never used them themselves. The oils that were linked to killing cats and harming animals were also never graded or evaluated by veterinarians who condemned them."
"My current recommendation when considering essential oil use for cats is to choose oils that are used often, have been used in many cats, and to use them with techniques that cats enjoy."
"One factor that is true for cats, is that they are notoriously deficient in the Cytochrome p450 liver metabolism pathway. This particular pathway is utilized for the metabolism and excretion of all sorts of chemicals from their body, including traditional medications. A cat's liver just does not metabolize items in the same manner or efficiency as a large dog or a human. This fact has made cats unique in veterinary medicine, no matter what the substance may be that we are exposing them to. For example, certain traditional Non-Steroidal Anti-Inflammatory (NSAID) drugs can be used in dogs, but if given to a cat, has a high likelihood of causing significant damage to organs and even death."