"He would never turn his nose up at grain," unless he was sick, she said.
Suspecting it was the mosquito-borne West Nile virus, which attacks the brain and spinal cord, a veterinarian placed the animal on steroids and ordered the harness, she said.
Infected mosquitoes carrying the West Nile virus can spread it by biting a human, animal or bird.
While in the harness, the animal received 24-hour care, with Starr and other volunteers taking shifts to make sure Goldie did not become tangled in his harness.
Goldie was removed from the harness on Aug. 23 and has regained his normally hearty appetite, Starr said.
The horse may take up to a year to regain his strength and be returned to service as a lesson horse for blind students, she said.
A gentle animal, Goldie is patient with timid riders and gives them the confidence to canter, she said.
Starr said that in the 15 months since she has owned Goldie, she has grown close to the friendly animal.
"It was a blow" to hear he had West Nile virus, "but we we're kind of relieved because we caught it in time and treated it. Before we did the testing we had no clue what was wrong," she said.
"We feel lucky that he's expected to recover. I hope we never see it (West Nile) again," Starr said.
There is no West Nile vaccine available for humans. A West Nile horse vaccine is available.
At least 27 birds, most of them crows, have been tested for the West Nile virus, Laurie Bucher, the Washington County Health Department's director of environmental health, said Friday.
People can avoid getting the West Nile virus by wearing insect repellent and not going out at dusk when mosquitoes are active, said Jessica Seiders, spokeswoman for the Pennsylvania Department of Health.
Less than 1 percent of the population who get the virus experience flu-like symptoms, such as fever, headache and muscle aches, she said.
In rare cases, the virus can lead to high fever, disorientation and death, she said.
People older than 50 and those with weak immune systems are most susceptible to medical problems because of the virus, she said.