The longer, coarser outer hairs of a double coat that repel water, dirt, and UV radiation. Guard hairs protect the soft undercoat beneath and give the coat its visible color and texture.
Understanding guard hairs prevents the mistake of shaving or over-stripping a double coat, which can permanently damage the coat's protective structure.
When deshedding, remove dead undercoat while leaving guard hairs intact — this preserves the coat's weather-resistant properties.