A drug used to treat humans with Parkinson's disease has been pulled off of the market by the U.S. Food and Drug Administration.

But, horse owners who use the drug Pergolide said that will leave them unable to treat horses suffering from Cushing's syndrome.

While the drug does not cure Cushing's, it is known to reduce symptoms and dramatically increase the quality of life for the animals.

One veterinarian said that certain pharmacies have enough Pergolide on hand to meet demand until an alternative can be found, while another veterinarian said the removal will cause severe problems for horse owners nationwide.

She and several others are now calling on the FDA to issue an exception on the drug so that it may be used to treat sick horses.