CHAPTER TEN: LYMPHATIC DISEASES
Definitions:
Lymphangitis – ______________________________________________________________
Lymphadenitis – _____________________________________________________________
Lymphadenopathy – __________________________________________________________
Lymphoma - ________________________________________________________________
The Lymphatic System and Inflammation
The lymphatic system is the mechanism by which transudate and exudate are removed from the extracellular space. The vessels of the lymph system have a relatively negative hydrostatic pressure in comparison to the extracellular space, which acts as a sort of vacuum to remove fluid from the extracellular space. Once fluid enters the lymph vessel it is considered lymph fluid. All lymph fluid is filtered by at least one lymph node before the fluid is returned to general circulation. In this way the lymphatic circulation helps to remove toxins and pathogens from the blood. Every lymph node has resident macrophages that kill pathogens filtered out of the lymph fluid. Although the lymphatic system is designed to work with the immune system to protect the body from pathogens it may be a vector for the spread of disease. Some infections can be spread through-out the body by the lymph circulation and particular types of cancer have been shown to metastasize through the lymphatic system.
‘Stocking Up’
Stocking up is a generic term for a build up of fluid occurring in the lower limbs. The flow of lymphatic fluid up the limb depends on pressure differences and movement in the tissue surrounding the tiny lymphatic vessels of the lower limb due to the absence of valves. The most common cause of stocking up is . Stocking up is a bilateral, mild swelling or edema within the pastern and fetlock areas. It is usually limited to the hindlimbs only and doesn’t cause pain or lameness. The overlying skin will remain normal with possible mild pitting when pressure is applied.
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