They don't really have a name for a group of race horses as far as I know. Cause generally when racing, they compete against each other. And it's a solo race for the win. So there is no association with the other horses, like for example a team of Basketball players.
There is no real name for a pack of race horses or a herde of race horses, or horde of race horses..............
A Race
paddock
Race Program
there is no particular race that 3 horses race in. there are more than 3 horses in a race which name is unmentionable figure it out by yourself i am not your mother don't even dare to improve this honest answer i have written i know i am cool
A 'herd' is a group of horses.
A herd
They are most famous for the Quarter-mile race, the race they get their name from.
A group of wild horses can be called a field, a herd, a set and also a remuda.
A group of horses is called a herd. A male horse is called a stallion.
A group of horses is commonly referred to as a "herd."
A group of horses, whether they are family or not are always called a herd.
Stud