What main clinical sign is observed in sheep affected by Haole koa toxicity?

The primary clinical sign observed in sheep affected by Haole koa toxicity is fleece loss. Haole koa, also known as the invasive tree species, can produce compounds that are harmful to certain livestock, including sheep. The toxins present can lead to a disruption of normal hair and fleece growth, resulting in significant fleece loss, which is a prominent indicator of toxicity.

When sheep are exposed to these toxins, the physiological stress and skin irritation can affect hair follicles directly, leading to abnormal fleece shedding. This condition can severely impact the quality of the wool and the health of the sheep, as fleece is essential for regulating temperature and protecting the skin from environmental factors.

Understanding this clinical sign is vital for veterinary practitioners working with livestock in Hawaii, as it helps in diagnosing and managing cases of Haole koa toxicity effectively. The other options listed do not directly relate to the specific toxic effects associated with Haole koa exposure in sheep.