Healthy horses are easy to spot south on Midway Road in Donna.
But travel to where the pavement becomes dirt and neglected animals are what some people find.
"It made me sick!" Heather Stover, a horse rescuer said.
She and 2 others are credited with trying to save the horse.
Laramie Fann and his father Cal first stumbled upon the abandoned animal on April 14th while out with their dogs near the water treatment plant.
"It was the moment that I looked into her eyes and she looked back at me that I knew there was tragedy," Laramie with Paw Posse said.
"Its gums were as white as white can be," his father Cal said. "It was so anemic. It was thin. As it turns out it was very thirsty."
They believe the horse may have been neglected for as long as a month.
But the two are dog rescuers and needed help with the horse.
Their friend Heather Stover, who works with Bluebonnet Equine Humane Society, specializes with horses.
"On a scale of 1 to 10 with 10 being the worst this is probably a 10," she said about the condition of the mare. "One of the worst I've seen."
Heather points to the horse's leg injury.
A massive infection near the hoof area looked to her to be untreated for far too long.
The Hidalgo County Sheriff's Department had the animal put down under a veterinarian's advice.
A criminal case as to who may have dumped the horse remains a mystery.
"It's a heartless act," Laramie said. "It's tragic that people act like this these days."
Heather wants whoever's responsible to come forward.
"It's the right thing to do," she said.
Cal wants people to know that any animal left abandoned is a terrible choice.
"It's just unforgiveable," he said.
They want justice for the nameless horse.
All three animal rescuers remind people to contact a rescue group or authorities if they spot abuse.
Both Bluebonnet Equine and Paw Posse can be found on Facebook.
The Hidalgo County Sheriff's Department says the case regarding the horse has gone cold.
Anyone with information should contact 956-668-8477.