Which sign indicates that a pony may need shoeing?

The indication that a pony may need shoeing is often shown through loose nails pushing up from the hoof wall. This sign suggests potential issues with the integrity of the shoeing process or the fit of the shoes. When nails become loose, it can lead to discomfort for the pony and may affect its performance and overall hoof health. Properly fitted shoes should have nails that are secure and not causing any distress to the hoof. Observing loose nails is a clear sign that the pony may not be adequately shod and requires attention to ensure its well-being.

The other options do not directly relate to the need for shoeing. Hair growing longer than average could indicate issues with grooming or hoof care, but not necessarily the need for shoes. Increased appetite can stem from various factors such as changes in routine or environmental stress but does not indicate a direct need for shoeing. Changes in coat color are also unrelated to hoof care and shoeing requirements, often linked to health, nutrition, or seasonal changes.