Discharge is any substance — fluid, pus, mucus, blood, or exudate — that flows or oozes from a wound, lesion, or body opening. In equine medicine, discharge is a clinical sign evaluated by character (clear, cloudy, purulent), color (white, yellow, green, red, brown), consistency (watery, thick, mucoid), and location. The combination of these features points toward the underlying cause and guides the urgency of veterinary attention.
Common locations and their significance: nasal discharge is normal in small clear amounts; bilateral mucopurulent (yellow-green, from both nostrils) discharge suggests respiratory infection or strangles. Ocular (eye) discharge that is clear and minimal is common with dust or irritants; thick or purulent ocular discharge indicates infection. Discharge from a wound indicates the wound is producing exudate — clear or slightly pink serous fluid is normal in early healing, while purulent (pus-containing) discharge indicates bacterial infection. Discharge from the hoof, particularly in the coronary band area or from the sole, is a classic sign of abscess drainage as a common source.
The depth of dermal involvement context matters: discharge that originates from a wound or lesion that has not penetrated to living tissue is an epidermal issue; discharge from a wound reaching the dermis or deeper signals live-tissue involvement with greater infection risk. In all cases, persistent, foul-smelling, or bloody discharge warrants veterinary assessment. Discharge accompanied by swelling, heat, lameness, or systemic signs such as fever or elevated heart rate requires prompt attention. See also pasture safety for wound risks that can produce discharge-causing injuries.
Further Reading
Medical discharge as a clinical sign is described in the medical discharge article on Wikipedia. Systemic conditions in horses that present with abnormal discharge are addressed in the Merck Veterinary Manual section on Disorders Affecting Multiple Body Systems of Horses.