• The severity of signs varies with the age of the animal and duration of the illness.
• Signs may be mild.
• Horses less than 1 year old may have a fever only.
• Horses 1 to 3 years old develop fever, depression, mild limb swelling and lack of coordination.
• Adults exhibit the characteristic signs of fever, poor appetite, depression, reluctance to move, limb swelling and jaundice.
• Fever is highest during the first 1 to 3 days of infection, but may last for 6 to 12 days.
• Signs become more severe over several days.
• Any existing infection (such as a leg wound or respiratory infection) can be made worse.