All Natural Herbs for Horses with Lumps Under Tail Your equine or horse’s health is important. If you detect lumps under tail, there is a good chance that these bumps under tail are actually melanoma skin tumors. If you reduce the size of the melanoma and get proper care for your horse or equine, you can substantially increase comfort and overall health. Proper diet and nutrition is also a part of helping your horse have better overall health, by preventing several issues. Trusted by vets and professional riders, our alternative, natural herbal supplements can be a part of your equine’s overall health and well-being.