Originally Posted by Gimme A Dream
Potatoes has a mild natural antibiotic that naturalist humans use for arthritis. It won't harm her to give it every day, for the rest of her life. My horses always have potatoes instead of apples and even carrots.
If possible keep her out of the barn as much as possible. I got rid of my barn and keep all my horses outside 24/7 now because arthritis is a very real ailment prone to horses who are not moving around a lot.
Since arthritis is not an infection, antibiotics (from any source) aren't going to treat it. There are cases of septic arthritis, but these are from wounds that penetrate the joint capsule--infection sets in and causes inflammation in the joint which leads to cartiledge damage and bony changes. The majority of arthritis cases are simple wear and tear on joints from activity.
You can find lots of good information on arthritis by using the links below: The Horse: Joint Disease The Horse: Ailments/Syndromes | Arthritis
As for the "ailment prone to horses who are not moving around alot", it's not the lack of movement that causes arthritis but it does cause the symptoms to worsen. Arthritis is caused by damage and bony changes to joints--most often caused by repetitive concussive work---jumping, running, sliding stops, spins, hard turns at speed (like around barrels).