Potomac Horse Fever is known for the Potomac River. Originating in Eastern US it had been found in other parts of the US and Canada. It is a seasonal virus that is in late spring to early fall. The signs include High Fever, Diarrhea, Laminitis, mild colic and low gut sounds. Uncommon in pregnant mares it can abort a fetus between 90-120 days or 2nd tri-mester. If it has been found in an area it may reaccur for several years and there are killed vaccines and a vaccine tied with rabies. None can prevent the abortion of a fetus. Treatment includes the vaccine, which should me given in middle summer.