To find this information, I recommend:
* Checking the Howrse website: Look for official breed lists or forums where players discuss rare horses.
* Consulting Howrse communities: Search for online forums, Discord servers, or Facebook groups dedicated to Howrse.
* Asking other Howrse players: If you know anyone who plays the game, they might know which breeds are considered rare.
Remember that the rarity of breeds in Howrse can change over time due to breeding programs and events.