After one attack there is always an increased liability to a second, and great care should be taken to give the subject daily exercise, or where this is impossible, to reduce the feed, give a dose of saltpeter, and turn into a yard or roomy loose box on the idle day.
In chronic thickening of the limb, an evenly applied elastic bandage, extending from the hoof up, regular feeding and exercise, washing daily with a weak iodine lotion, and the internal use of iodide of potassium and other diuretics, with bitters and even iron tonics may be used.
INFECTIVE LYMPHANGITIS. TRAUMATIC LYMPHANGITIS.
Infection varied, through wounds, autogenous. Simple irritation, simple lymphangitis. Causes, sun’s rays, bruises, other injuries, lymph coagulation from heat, cold, chemical irritants, and coagulants. Germs in blood act on debilitated tissues, lymphatic constitutions, anæmic, overworked, or starved. Insect bites, claws, teeth of carnivora, foul instruments, fingers or clothes. Bloodless wounds dangerous. Distal parts of the limbs exposed. Fresh wound exposed, granulating less so. Most microbes enter by the lymphatics. Symptoms, extension from wound, swollen lymphatics, reticular lymphangitis, tubular lymphangitis, farcy, tuberculous case, slough. Fever variable. General infection. Joint infection. Chronic cases. Lesions. Diagnosis, from phlebitis. Treatment, antiseptics, diet, eliminants, antithermics, blisters, mercurial ointment, iodine, lancing, tonics, massage, bandage.
Under this heading must be named not one specific disease but a group of infections entering by the lymphatic vessels and developing inflammation of their substance. They may be divided into two classes: those caused by infection through external wounds and those in which the poison already in the system becomes localized on a weak or exposed tissue.
A third class must be included, in which there is no recognizable poison but simply a local irritation which leads to coagulation or other alteration in the lymph, or disease of the lymphatic vessels.
This subject belongs rather to surgery than medicine but it seems necessary to contrast it here with the plethoric form of equine lymphangitis. Most of its forms pertain to infectious diseases and will be treated in connection with these.
Causes of Simple Lymphangitis. Formerly many forms of lymphangitis were ascribed to mere local irritation; a superficial form will occur from exposure to the rays of the sun, and an inflammation attendant on a bruise or other injury with unbroken skin, may cause local inflammation of the lymph vessels and enlargement of the adjacent lymph glands. As we have seen above coagulation of the lymph and fibrine embolism may induce local inflammation in the walls, and this may occur in connection with excessive heat or cold or the presence of chemical irritants and coagulants. These cases are however rarely serious and the tendency today is to trace nearly all cases to infection, from germs already present in the lymph or blood, or introduced through a wound or sore. The effect of germs already circulating was shown in the beautiful demonstrations of Chauveau in regard to calves subjected to castration by subcutaneous torsion (bistournage). In the healthy calf the simple operation gave rise to little disturbance. The healthy calf injected with septic liquids equally escaped visible trouble. But the calf injected with septic liquids and then subjected to bistournage had a fatal infecting inflammation. There is a strong presumption that, in lymphangitis, starting from an injury with no external sore, the germs were already present in the blood or tissues but were unable to do any serious damage until the injured and weakened part or organ offered an area of lessened resistance to their colonization. Following the same line of thought it has been noticed that animals of a coarse texture, and lymphatic constitution (heavy draft horses and animals raised for the butcher), and such as are debilitated by anæmia, overwork, or poor and insufficient nourishment are above all liable to be attacked by lymphangitis.
The insertion of the septic poison may take place through the bites of insects, the claws, or teeth of carnivora that have been devouring tainted or infecting meat, through the lancet or operating instrument of the surgeon, by his fingers or the dust from his hair or clothes. The wound is perhaps more likely to be infecting if it leads to no effusion of blood, but affects only the thickness of the epidermis, as there is less chance for the washing out of germs by the flowing blood, and there is less care to employ antiseptics. Wounds in the feet and lower parts of the limbs are specially liable to infection by reason of their frequent contact with manure and decomposing organic matter in the soil.
A fresh wound, in which the lymph spaces are exposed, is somewhat more open to infection than one that has advanced to the stage of granulation, the layer of unorganized lymph and cells acting as a slight barrier to the passage of the microbes.