Final answer:
The contagious horse disease causing lymph node abscesses is known as strangles, caused by Streptococcus equi, and the correct answer is b) Strangles.
Step-by-step explanation:
The disease described in the question, which is highly contagious among horses, causes abscesses in the lymph nodes, and is caused by bacteria, is known as strangles. Strangles is an infection in horses caused by the bacterium Streptococcus equi. This disease is characterized by severe inflammation of the mucosa of the head and neck, leading to the formation of abscesses in the lymph nodes. Strangles can cause fever, difficulty swallowing, and can lead to severe respiratory problems. Due to its contagious nature, horses diagnosed with strangles are often quarantined to prevent the disease from spreading. The correct answer to the multiple-choice question is b) Strangles.