* Consistency: The shoulder height is a more consistent measurement than the head height. Horses' heads can vary significantly in size and shape, even within the same breed, making it difficult to get a reliable measurement.
* Practicality: Measuring to the shoulder is easier and faster. It's a more accessible and stable point on the horse, allowing for a more accurate measurement without the need for specialized equipment.
* Function: The shoulder height is a good indicator of a horse's overall size and build, which is relevant for its suitability for different types of riding and work. A horse's shoulder height is directly related to its leg length, stride length, and overall movement capabilities.
* Historical Reasons: Horse breeding and racing traditions have historically used shoulder height as the standard measurement. This practice has been in place for centuries, and it's become the accepted norm in most parts of the world.
In conclusion, measuring horses to the shoulder is a practical, consistent, and functionally relevant method that has become a standard practice in the horse industry.