I like the contrast of colors in the first photo but the background is a little distracting. It kinda clutters the "negative" space.
In the second photo I like the juxtaposition between the book and and bridle. The photo seems a little dark though. In addition, to someone who does not know horse's they might not understand what the book is tangled up in -- it looks like it is sitting in a pile of leather straps. Maybe if you could rearrange the bridle to highlight a certain aspect such as the bit so it is more obvious what it actually is.
The third picture is a nice shot. There is a clear horizon line, however, the quality of the photo is pixelated which throws off the "natural" saturation of colors, particularly in the sky. I can't really tell if it is cloudy or clear.
I like the forth picture, nothing to rally critique except that it would be an even better shot with a professional lens/camera.
In the seventh photo the small area of of the upper eye which shows a reflection has a green hue which kinda destroys the contrast between the black/white and the brown iris in my opinion. It is a bit confusing whether or not you meant it to look like that.
In the eight photo, it's a creative idea but the layout of the bridles looks sloppy. What are you trying to show the viewer?
Photo number 10: it's a cute shot but it is blurry and pixelated. The height of the fence compared to the six of the pony is a bit distracting to me also. I think this picture would be very nice if it was cropped down to a close up of the horse's head. Basically, capturing the expression of the horse through his eyes maybe even get some of his boroque neck and his wild mane with his knee partially in the shot to make it more interesting.
IN the last photo I really like the lighting and the shadows. The ribon that reads "second" is a bit too vertical and hard to read. Also the vague scribbles thet resemble a horse in the upper left corner I think should be shown more. It's a little awkwardly placed.
Good job, keep it up.