On October 20, 2009, the Texas Animal Health Commission announced that a Texas horse exhibiting clinical signs of Equine Piroplasmosis (EP) had been diagnosed with the disease. In subsequent testing, in multiple counties in South Texas, over 280 horses have been determined to be positive for the disease. Since this time over 25 positive premises have been identified in Texas and since then 18 additional premises in 14 states including Florida have had positive EP cases related to this single outbreak. Health requirements have previously been placed on horses moving from Texas to Florida to prevent the spread of EP and competent vector ticks. This rule is necessary to impose the same health requirements on horses from Texas and any other locations, regions, states, or U. S. possessions where EP is determined to be endemic, based on known positive cases, prevalence of disease, presence of competent vectors, and/or evidence of natural transmission of the disease. EP is considered a foreign animal disease, not endemic to the United States. EP is a blood-borne parasitic disease primarily transmitted between horses by ticks or contaminated needles and is not directly contagious from one horse to another. Currently, EP is considered an untreatable disease and under state and federal agreement, all horses testing positive for EP must be quarantined for life or be euthanized. Ticks are the natural method of transmission of EP and those tick species which are known to be efficient at transmitting the EP organism are not believed to exist in Florida. If the tick vectors, detected in endemic areas, become established in Florida and facilitate the spread of EP among Florida’s 500,000 horses, the impact would be devastating. Acutely affected horses can have depression, fever, anemia (decreased red blood cells) jaundiced (yellow) mucous membranes and low platelet counts and can die from the disease. In its milder form, EP can also cause horses to have roughened hair coats, constipation, colic, generalized weakness and lack of appetite. Some horses become chronic carriers of the disease showing little clinical signs but having the ability to transmit the disease to other horses via ticks. Treatment of infected horses has not been shown to be effective in eliminating the organism (Theileria equi) and infected horses must remain under quarantine. In an EP incident in Florida in 2008-2009 the Department spent over 4,800 hours managing the disease and testing more than 200 horses. During the incident the owners of 20 positive horses elected to euthanize their animals. Additional industry losses were incurred as many horses were not imported into Florida during the peak winter show season and Canada required testing on Florida horses. While the disease investigation was costly, the impact was much less than could have been the case if a tick vector was present to spread the disease. Currently, it costs Texas more than $14.0 million dollars a year in its efforts to eradicate a tick which transmits an EP like disease in cattle. If EP infected horses or a species of tick efficient at transmitting the disease were established in the state countless Florida horses would have to be euthanized or quarantined for life. In addition, many states and countries would not allow importation of Florida’s horses, potentially ruining the equine industry which produces goods and services of over $3.0 billion per year.