What is a common indicator that a horse may have severe eye issues?

A ruptured eye is a significant and alarming condition that typically indicates severe injury or disease affecting the horse's eye. When the eye is ruptured, it can lead to serious complications, including loss of vision or even the eye itself. This condition usually results from trauma, infection, or a penetrating injury, and it can manifest with severe pain, swelling, and immediate medical attention is needed.

In contrast, while frequent blinking, eye irritation, and pupil dilation can suggest various eye-related issues or discomfort, they do not necessarily indicate a severe problem. Frequent blinking may denote minor irritation, and pupil dilation could indicate a range of non-severe conditions. Eye irritation is also common and can often be treated without urgency. Thus, the distinction lies in the severity and immediacy of a ruptured eye as a critical health concern for the horse.