First of all, you should get as much information about the genetic aspects of the horse as possible. If the tail of a horse it genetically thin then it becomes too difficult to make it appear fuller. However, doing certain things will make it look better.
If your horse’s tail is thin because of any other reason, not genetics, then it will not be difficult to make it appear thick.
The most important thing is that you need to brush your horse’s tail for at least once in a month. It is better to do this twice in a month but do not do it on regular basis because frequent brushing can cause hair loss that will lead to thinning the tail.
The most used products for the horse tail are Cowboy Magic and Show Sheen. Make sure you make a proper use of these products in order to get good results.
You should hold your horse’s tail from the base for brushing it as it is the most effective manner to brush it in a free-flow way.
Now take a hard brush for brushing the tail bone of your horse. Make sure you brush it lightly in which will stimulate the blood flow and will help in growing new hair. It will help in making the tail thicker as desired.
Make sure you trim the tail hair of your horse with regular intervals. Doing it with an interval of 4 to 5 months is more appropriate which will help in making the hair strong and thick. It will also help in eliminating the blunt edges of the tail hair.
If you feel that your horse’s tail hair have become dry, then you should use a conditioner to keep them soft because softness will keep them away from breaking.