Things to watch are numerous !! First of all it is necessary to know the exact area and that the meadow is accessible. You must also know if the terrain is unfathomable zone or not and also if it does not have a shelter, if you can build one !! And also if you have a water point or if you can bring a tank to have water. Be careful with the water points in a meadow because in the stagnant water the diseases are very numerous! A basic test to see the quality of the water is in my opinion necessary and a must! If it is water "moving" for example river, creek, I would also test for water to be on and avoid any diseases; Knowing that another water point is strongly recommended for drought or dam situations.
The second thing very important are the barriers to their strength, if the stakes are planted very deeply and if they are high enough and if the ground is well defined (space between barrier and path). Also to watch is if you can put electricity on the barriers or if it is already there.
Last thing to watch is if in the meadow there are toxic plants for the horse! If there are none, there is no need for further development, but if there are toxic plants / trees, either remove them or, for the trees, delimit an area around Of the tree so that the horse does not have access!
I hope this helps !!