NASHVILLE (AP) — The state veterinarian's office is investigating an outbreak of a disease involving 17 horses in Middle Tennessee.

The Agriculture Department said in a news release that a group of racing quarter horses tested positive for equine piroplasmosis. All are connected to the same location in Rutherford County.

The release said equine piroplasmosis is a blood parasite that affects horses. It can be transmitted through infected ticks but is more commonly spread by blood and blood products through shared needles or syringes, or improperly cleaned and disinfected dental, tattoo, surgical or blood product equipment.

It can take as long as 30 days for a horse to test positive after exposure. Early signs can range from weakness and lack of appetite to swelling of limbs and labored breathing.

The agency emphasized using new sterile needles and syringes and cleaned and disinfected equipment on each horse.