Lymph nodes are small round masses of immune tissue located throughout a horse's body that help protect it from infection and disease. Linked by lymph ducts throughout the body, they remove antigens from lymph fluid. Swollen lymph nodes may be a symptom of illness.

A wide range of conditions, from trivial to life-threatening, can cause swollen lymph nodes. Note the locations of the swollen lymph nodes, take your horse's temperature and observe any other abnormal symptoms. Call your veterinarian to determine the appropriate treatment.

Swollen lymph nodes under the jaw and along your horses throat latch could point toward a disease known as strangles. Strangles is an infectious, contagious upper respiratory infection caused by the bacterium Streptococcus equi equi. Symptoms include swollen or abscessed submandibular lymph nodes, fever, nasal discharge, cough and depression. Call your veterinarian immediately if your horse exhibits any of these symptoms.

Because the causes of swollen lymph nodes are various, there is no single solution or prevention. As always, keeping your horse's environment clean, vaccinations current and limiting your horse's exposure to stress is your best line of defense against disease.