You have took on quite a challenge here and did pretty well under the circumstances.

Your focus and composition are ok, but the scene itself was your enemy.

The lighting and surroundings of this location are hard to overcome. The soft lighting is good for the detail in the horse, but there is a lot of unwanted detail in this setting that shows up all to well. There is no contrast between the subject and its surroundings to the left of the doorway.

The window in the background detracts from the subject. As does the grass in the mesh.

You can crop in tight on the left and go to a vertical format.
You may also crop a little clutter from the right to improve the photo.

The toning imparts a little touch from a different time and complements the horse.

If you get the chance to take more pictures of this pretty animal, get the owner to bring it our into the open where you can simplify the surroundings and contrast the horse against the background. Experiment with perspectives; get in close and capture its personality. (Do a tight closeup of the owner and the horse's faces, and the owner will always remember you. When the animal passes on your will have the owners undying gratitude.)

Hi...I love horses and I'd love to see this one in an open space somewhere. Someplace where there is green grass and trees maybe. Or if you could get a close up shot of just his face. I do feel the lighting here isn't good at all, but I do appreciate your efforts in trying for this photo. Please don't give up, but just enjoy what you're doing and appreciate the input that other photographers will give to you. Caedes has a lot of really nice people, and they will always be helpful.
Looking forward to more photos by you soon..Verena

I agree with what is stated above. I would have cropped this a bit to take some of the clutter out. Otherwise I like the coloring and the subject of course is beautiful.

You chose a tough subject Emily but I can see why you like it. I suggest you crop all the white on the left out and crop the right hand side to the door handle. Then make it a greyscale (Black and White). You’ve done quite well really and just a couple more steps can make it even nicer.

I agree with most of the above comments, but the major problem is with the exposure itself. All the highlights on the horse are either lost or subdued. The square format crop is primarily from the left side in almost as far as the window on the back wall.
Also a very small amount from the top border to halfway to the horses ears.
With the right amount of contrast and Gamma correction it's a gorgeous portrait, and the items on the front wall now compliment and integrate nicely. The tone of this looks like it may be an "OLD PHOTO" effects filter, and in my opinion they rarely look good. I don't think I've ever gone this far but after seeing this reworked, I'd be happy to have it in my own
collection. The basic ingredients are all there.