Final answer:
Teat chapping or frostbite dermatitis is the disease that causes the described symptoms in dairy heifer teats during winter. It is similar to contact dermatitis but is primarily due to cold weather. Delayed-type hypersensitivity is another skin reaction but is immune-related.
Step-by-step explanation:
The disease that typically affects dairy heifer teats during the winter months, causing leathery and/or ulcerated/thickened teat skin, is known as teat chapping or frostbite dermatitis. This condition is comparable to contact dermatitis, where the skin reacts to irritants like latex, but in the case of dairy heifers, it is often due to the cold and harsh environmental conditions. Another disease involving skin reactions is the delayed-type hypersensitivity reaction, such as a tuberculin reaction, which is an immune response to a previous exposure to the antigen.