This poisonous plant has always been a cause for concern for horse owners. The plant is about 2m tall with broad curly leaves and yellow flower heads. Horses do not normally eat fresh ragwort as it has a bitter taste but when dried (such as in hay) it can become a danger. Signs that a horse has been poisoned include yellow mucus membranes, depression, and lack of coordination. If a sufficient quantity is consumed (claimed to be 3-7% of bodyweight but scientific literature has documented survival at 20%) this can result in cirrhosis of the liver.

Recurrent Airway Obstruction (formerly known as Chronic Obstructive Pulmonary Disorder) is a relatively common allergic respiratory disease in horses. Symptoms include a chronic cough, nasal discharge and impaired breathing. One of the most important factors of managing this disease is minimising the horses exposure to the allergen. In such a case feeding a hay replacer such as Hi-Fi Senior is strongly recommended as both the grasses and alfalfa included in this product have been high-temperature dried to provide a consistently clean forage source.