(taken from the SWEM Wiki)
Treatment
Horses should have safe and secure accommodations that follow welfare standards.
Horses should have reliable access to food and water.
Horses should have clean of stall and turnout spaces.
Horses should remain untacked if they're not required to be.
Horses should not be left tethered for long periods of time, as they will be unable to attend to their needs.
Horses should not be harmed or killed.
Building / Barn Standards
Doorways: 2b+ wide and 4b+ tall (minimum)
Walkways: 5b+ wide and 5b+ tall (4.5 optional on edges for detailing) (minimum)
Security: All entryways/exits must have a secure gate to prevent escape. Walls should be tall enough (2b+) to prevent escape.
Stallions and mares should stay separated at all times. You can have them in a separate barn or separate wings of a single barn.Â
Food and Water
Horses should always have access to:
Food: As either forage (grazing on grass) or feed (quality bale, timothy, alfalfa, or sweet feed)
Water: As either an infinite water source, or adequately filled water container (trough, half barrel)
Stalls
A good-sized stall allows a horse space to turn around and lay down with decreased chances of them getting stuck in walls. It should also allow space for a rider to provide unobstructed feed items and bedding and to safely interact with and maneuver a horse into and out of the stall.
Size: Stalls should be a minimum of 5x5, and a maximum of 12x12. Foaling stalls should be a minimum of 9x9, and a maximum of 12x12.
Footing: Stalls must have rubber mats placed underneath shavings, and shavings must cover at least 80% of the stall floor.
Runs/Paddocks
Runs, or paddocks, are fenced-in attachments to a stall, offering limited grazing space or just outdoor access with soft footing.
Size: Paddocks should be a minimum of 5x5 per horse.
Footing: Paddock footing should be soft and natural. Grass, dirt, or sand is recommended. Ice, pavement, concrete, or other hard surfaces shouldn't be in your horses' paddock area.
Terrain: Paddocks should not have extreme terrain.
Pastures
Pastures differ to paddocks as they are generally larger and intended for sustainable, longer-term grazing, exercise, and solo or group turnout of several horses at a time.
Size: Pastures should be a minimum of 10x10 per horse.
Footing: Pasture footing should be soft and natural. Grass, dirt, or sand is recommended. Ice, pavement, concrete, or other hard surfaces shouldn't be in your horses' pasture area.
Terrain: Pastures should not have extreme terrain.
Grazing: Pastures should offer mostly grass, but dry lots are permitted if bales are provided at all times.
Water: Pastures should have water via troughs and/or natural resources.
Stallions: Stallions shouldn't be turned out together or with mares/geldings. Only one stallion is allowed per pasture for safety reasons.