Ten horses authorities believe were smuggled into Texas across the Mexican border are infected with Equine Piroplasmosis (EP), a condition routinely found in Mexico and numerous other countries around the world, and a condition that can prove fatal to horses and could create major constraints to interstate and international movements if left undetected.

U.S. Customs and Border Patrol (CBP) agents seized the horses near the Rio Grande River in Hudspeth County, just south of El Paso. USDA’s Animal Plant Inspection Service (APHIS) took control of the animals which are being quarantined in Presidio (Texas) pending an investigation. CBP officials say they believe the horses may have been led across a shallow river crossing near Indian Springs. All ten of the horses were confirmed with the disease.

APHIS officials say illegal movement of animals across the border is an ongoing problem in that region.

"In some places the Rio Grande poses no barrier at all to foot traffic for man or animal," reports Dr. Grant Wease with USDA-APHIS in El Paso. "In 2011, approximately 280 head of cattle and 160 head of equine—mostly horses—were intercepted by USDA officials along the Rio Grande."

Last week, Kevin Good, assistant Texas State Parks director, warned of escalating problems with feral burros crossing the Rio Grande and taking up residence in the Big Bend Ranch State Park, where they pose a threat to native wildlife because they compete for forage and water resources.

“We believe most of these animals were abandoned by their owners in Mexico and they have crossed the border on their own in search of food and water,” Good said.

He says whether these burros are infected with EP or other diseases are unknown because so far officials have been unable to capture a live burro. The remote and rugged landscape makes tracking the animals difficult and even when they are located, the terrain rarely allows for easy access for tracking and transportation.

Officials think that these ten diseased horses may be part of an organized smuggling operation. CBP agents say the horses may have been stolen from Mexican ranches and brought across the border to sell. Because of the rugged landscape and miles of remote river crossing, detection of such smuggling operations are difficult.

Dr. Wease says drug violence in Mexico poses another problem for inspectors in the remote regions of the border. He says illegal activities and the presence of all types of smuggling operations in the region even makes monitoring and inspections of legal animal imports a major risk along the border.

Officials with USDA and the Texas Animal Health Commission (TAHC) say an investigation is ongoing into the recent horse event. Officials are attempting to determine the point of origin and the intended destination of the animals.

TAHC recently passed EP rules requiring testing of race horses prior to entry into a Texas track, and numerous other states have done the same because of recent cases found among racing stock.

"Racing Quarter horses with some connection to Mexico appear to be at highest risk of testing positive to the emerging disease," says Dr. Dee Ellis, State Veterinarian and TAHC Executive Director. Although the interdicted horses were described as Thoroughbreds, they were considered more likely to be breeding type animals than race- ready horses.

"This situation highlights the ongoing border security problems Texas is facing, which leads to an increased risk of disease introduction for the Texas livestock population when animals enter our state illegally. I encourage all citizens that witness unusual activity regarding livestock movement near the Mexican border to contact their local law enforcement or animal health officials as quickly as possible to report the situation," Ellis published in a statement last week.

According to that statement, both USDA and TAHC are limited in providing inspection and monitoring services because of the vast and remote area where illegal operations take place on the southern border and because both agencies are facing escalating budget constraints.