What is the fine-grained topic of the following text: Contents include: "Manuscript Transmitted to the Veterinary College in 1816", "Navicular Joint Disease Unknown as the General Seat of Chronic Lameness of the Fore Feet", "Contraction", "Two Forms of Contraction", "The General or Apparent Contraction", The Occult of Partial Contraction", "Insidious Nature of Contraction", etc. Only return the topic.
Chronic Lameness in Horses due to Navicular Joint Disease and Contraction