One hypothesis is that bacteria causing foot rot may act in conjunction with the spirochete bacteria to cause the wart lesion. Although wet, muddy conditions seem to enhance the spread of the bacteria, heel warts have been found on cows in the desert Southwest, indicating that the spirochete bacteria are highly contagious and thrive and grow both in dry and wet environments. Wart lesions are usually found at the back of the rear foot near the heel bulb. The uniqueness is that the wart lesions are only seldom observed on the front feet of cattle. Manure on the back of the heel appears to help provide an anaerobic environment for the bacteria to grow and develop.
Early lesions are small, round and strawberry-like in appearance.
The disease appears to affect mostly first and second lactation cows. This would indicate older animals have developed a resistance to the disease. The hind feet are the most often infected. Symptoms include moderate to severe limping, with little or no swelling above the hair line of the foot. Animals with the symptoms seem to experience extreme pain at the site of infection.