HYPERÆMIA—CONGESTION OF THE SPLEEN.
Four hours after full meal in splenic diastole. In well fed, high conditioned. From obstruction of splenic or portal vein or vena cava, heart, liver, or pulmonary disease, inhibition from encephalon acting through splanchnics or vagi, microbes, ptomaines, toxins, paresis, albuminoid diet. Spleen may be seven times its normal weight. Lesions: simple blood engorgement: proliferation of pulp cells: increased friability; rupture; dark color; hyperplasia of trabeculæ—hypertrophy. Symptoms: none; or colic; palpation in ruminants; tenderness. Treatment: directed against the causative disease; quinine, cinchonine, eucalyptus, ergot, cold douche, electricity, puncture.
Considerable hyperæmia of this organ takes place physiologically in connection with active digestion in the first four or five hours after an abundant meal, and especially at intervals of a minute, during what may be called the diastole of the viscus. The supply of blood is also much greater in the well fed animal, than in the emaciated and impoverished one.
Pathological hyperæmias of a passive kind may occur as the result of obstructions in the veins leading from the spleen, such as the splenic veins, the posterior vena cava, or that part of the portal vein comprised between its junction with the splenic and the liver. Diseases of the right heart or its valves, of the lungs (emphysema), or of the liver which hinder the onward flow of blood and increase the blood tension in the vena cava or portal vein have a similar action. Perhaps we should include inhibition of the nerves (splanchnic, vagi) and nerve centres (medulla oblongata, cerebral cortex) which preside over the contraction of the splenic vascular walls, and of the capsular and trabecular muscles. There is reason to believe that the ptomaines and toxins of several microbian diseases, operate through these centres, while other such microbes and toxins operate directly on the spleen itself.
Active congestions of the spleen are most commonly associated with microbian diseases and may be attributed partly as above stated to the action of the toxic products on the contraction nerve centres, and on the splenic vessels and parenchyma, but also in no small degree on the active proliferation of the germs themselves in the splenic pulp, and of the splenic cells. Among the most notable instances of this kind are, in man, malarious, yellow and typhoid fevers, and, in animals, anthrax, and Southern cattle fever. In most febrile diseases, however, there is a tendency in this direction, which may be fairly attributed to the paresis of the organ and the delay of the blood in its pulp channels and spaces with the consequent local increase of microbes and toxins. The microörganisms can usually be found abundantly in such cases, in the liquid of the pulp, and in the interior of the leucocytes and other cells that go to make up its solid constituents.
It has been long recognized by veterinarians that acute congestion often arises in connection with a sudden transition from a poor or insufficient diet to an abundant and nutritious one and especially to one that is rich in albuminoids (beans, peas, vetches, lucerne, sainfoin, clover, trefoil, in the fresh or preserved condition). If these are not in themselves the direct causes of acute and fatal engorgements of the spleen, they at least contribute in no small degree to the overdistension of the pulp spaces, the paresis of the organ and its successful invasion by pathogenic microbes.
The acute congestion attendant on specific microbian infection may be estimated by the increase in weight of the spleen. In the Southern Cattle fever this organ, which is normally 1.45 ℔., is habitually 2 to 5 ℔s., and may reach 8 or 10 ℔s. and in anthrax an equal increase may be noted.
Lesions. In such cases the organ may appear as if there were a simple blood engorgement, and this is largely the case in the early stages, but with the persistence of the disease there occurs an active proliferation of the splenic cells and especially those of the pulp. With the hyperæmia the consistency of the organ is diminished, and still more so with the cell hyperplasia, so much so that in extreme cases rupture may ensue. The color is always darker (purple or blue), but this is only in part due to the abundance of blood and in part to the thinness of the splenic capsule. If the condition persists a hyperplasia of the capsule and trabeculæ ensues, and the condition becomes essentially one of hypertrophy.
Symptoms. In the slighter congestions there are no appreciable symptoms. In the more severe there may be more or less violent colic, but this is usually marked to some extent by the profound depression attendant on the specific fever which is the cause of the congestion. Palpation of the spleen is impossible in the horse. In ruminants it may sometimes be felt along the upper border of the rumen just behind the last rib on the left side. It is soft and yielding retaining the indentation of the finger. If manipulation produces signs of pain it is all the more significant.
Treatment. As a rule this is the treatment of the fever which determines the hyperæmia. Apart from this, laxatives, quinia other alkaloids of cinchona bark, eucalyptus, a current of cold water directed to the region of the spleen, or induction currents of electricity to the same region are also decided stimulants to contraction. Ergot has been used with alleged advantage. In cattle acupuncture of the spleen has been put in practice in anthrax.