Billary is a tick born disease. The parasites (protozoa) pass from the tick to your dog when they bite your dog. The parasite then enters the red blood cells where they multiple. The red blood cell then bursts releasing more parasites that in turn re enter more red blood cells. The end result of this is that if left untreated your dog becomes more and more anaemic and will ultimately die. Dogs that are extremely anaemic may require a blood transfusion to save his life. The best way of preventing this disease is to ensure your dog does not get bitten by an infected tick by maintain a good tick control protocol.