NASHVILLE (AP) — A Tennessee free-market group is suing the state over regulation of horse massage therapy.

The Beacon Center Legal Foundation on Thursday sued the Board of Veterinary Medical Examiners in Davidson County Chancery Court.

The lawsuit claims the board told Martha Stowe and Laurie Wheeler of Franklin they couldn't continue practicing horse massage therapy without a veterinary license.

It says the Board of Veterinary Medical Examiners enacted a regulation deeming animal massage a veterinary medicine.

The lawsuit asserts the regulation violates the state and federal constitutions.

It says the two women work with veterinarians, don't claim to be vets, and inform clients their services don't substitute veterinary care.

It calls the regulation arbitrary and irrational because vet schools don't require animal massage instruction, while other more invasive, dangerous practices are routine.