cow-horse

I'm pretty sure the "cow-horse" was supposed to be a paint a commenter named a colour pattern of paint- piebald.

Why Beat a Dead Horse... Jen 2009

On a cold morning a cow-horse does not like to be very tightly cinched or girthed up.

Ranching, Sport and Travel Thomas Carson

Caused by a cow-horse falling while running after stock;

Cowboy Songs and Other Frontier Ballads Various

Later a larger stamp of cow-horse came into use, even horses with perhaps a distant and minute drop of Diomede's blood in them -- Diomede, who won the first Derby stakes, run for in the Isle of Man by the way, and who was sold to America to become the father of United States thoroughbreds and progenitor of the great Lexington.

Ranching, Sport and Travel Thomas Carson

Suddenly the rope shot out, a cloud of white dust rose into the air as the cow-horse stopped in his tracks, a moment of suspense, and the black steer dashed frantically about seeking an avenue of escape while in his wake trailed the rope like a long thin snake with its fangs fastened upon the frantic brute's neck.

The Texan A Story of the Cattle Country 1921

But before he had gone twenty yards there was a thunder of hoofs in his wake and a cow-horse, his rider motionless as a stone image in his saddle, closed up the distance until he was running almost against the flank of the frenzied renegade.

The Texan A Story of the Cattle Country 1921

Bat Lajune grinned into the dark as the galloping cow-horse carried

The Texan A Story of the Cattle Country 1921

And below the rocks and bowlders were not actually piled on top of one another; there were clear spaces where a wary, wise, old cow-horse might possibly pick his way.

The Ranch at the Wolverine 1914

Immediately the well-trained cow-horse felt the strain it backed up and held the rope taut.

The Dude Wrangler Caroline Lockhart 1916

There was a desk made of boxes, and on the desk lay a shot-loaded quirt that more than one rebellious cow-horse knew to its sorrow.

Jean of the Lazy A 1915