Part 94

The pancreatic ducts are as a rule greatly dilated and thickened (in man they form enormous cysts, Senn, Osler), and the glandular tissue is atrophied, indurated (sclerosed), and of a brownish yellow color.

Treatment of such cases would be unsatisfactory. By way of prevention succulent food, abundance of pure water, and the correction of any infective catarrhal affection of the duodenum, or of the bile or pancreatic ducts would be specially indicated. Free exercise in the open air would be desirable.

PANCREATIC NEOPLASMS. TUMORS.

Often malignant, and secondary. Melanoma in white horse. Carcinoma in mare and dog. Epithelioma. Debility, icterus, abdominal swelling, emaciation. Treatment: laparotomy, or potassium iodide.

Tumors of the pancreas are quite frequently malignant, and show a preference for the head of the organ. They may be primary but are more frequently secondary.

In gray horses melanotic tumors are found, in connection with similar formations externally, and especially as age advances. Brückmüller found them of varying size, from a pea to a hazel nut, scattered through the pancreas and adjacent tissues.

Gamgee records a carcinoma of the pancreas of a mare.

Carcinoma is more frequent in this organ in dogs, the neoplasm having an irregular form, an imperfect line of delimitation from surrounding parts and a hard, fibrous stroma enclosing caseous centers, undergoing fatty degeneration.

Nocard reports an epithelial tumor of the head of the pancreas in a bitch. The animal which had been ill for six weeks was debilitated, emaciated, and icteric with a marked abdominal swelling. It died two weeks later, and necropsy revealed a whitish sublumbar tumor, the size of a large apple, with irregular rounded projections. This pressed on the posterior vena cava, surrounded the vena portæ and gall duct and completely closed the latter. Microscopic examination showed it to be an epithelioma. The liver was undergoing cirrhosis.

Treatment, usually hopeless, would be by laparotomy. If actinomycosis were present give potassium iodide.

DISEASES OF THE SPLEEN.

No guidance through palpation or secretion. Leukæmia. Lymphadenoma. Spleen a favorite culture ground for microbes. Congestions, engorgements, ruptures. Safety valve to portal system and liver. Rhythmic splenic contractions under reflex action.

The spleen even more than the pancreas is so deeply seated and so surrounded by other organs, that its diseases are not readily appreciable by physical examination, while the absence of any special secretion excludes the possibility of diagnostic deductions through this channel. Even the relation of the condition of the organ to the number of the leucocytes and red globules fails to afford trustworthy indications of disease, since leucocytes originate in other tissues as well as the spleen, and the destruction of red globules may take place elsewhere. Yet an excess of eosinophile leucocytes in the blood suggests hypertrophy or disease of the spleen, and an excess of leucocytes in general is somewhat less suggestive of disease of this organ (see Leucocythemia). If adenoma is further shown, in enlargement of lymphatic glands elsewhere there is the stronger reason to infer disease of the spleen.

The physiological relation of the spleen to the blood especially predisposes it to diseases in which the blood is involved. The termination of splenic capillaries, in the pulp cavities, so that the blood is poured into these spaces and delayed there, opens the way, not only for the increase of the leucocytes, and the disintegration of red globules, but for the multiplication of microörganisms which may be present in the blood, and for a poisoning (local and general) with their toxins. Hence we explain the congestions, sanguineous engorgements and ruptures of the spleen in certain microbian diseases (anthrax, Southern cattle fever, septicæmia, etc.)

We should further bear in mind that the spleen is in a sense a safety valve for the blood of the portal vein, when supplied in excess during digestion. In this way it protects the liver against sudden and dangerous engorgements, but it is itself subjected to extreme alternations of vascular plenitude and relative deficiency. This may be held to take place largely under the influence of the varying force of the blood pressure in the portal vein, but according to the observations of Roy on dogs and cats, it is also powerfully influenced by muscular and nervous action. He found rhythmic contractions of the organ due to the muscles contained in the capsule and trabeculæ, repeating themselves sixty times per hour, and which might be compared to tardy pulsations. He further found that electric stimulation of the central end of a cut sensory nerve, of the medulla oblongata, or of the peripheral ends of both splanchnics and both vagi caused a rapid contraction of the spleen. The spleen may thus be looked on not only as a temporary store-house for the rich and abundant blood of the portal system of veins during active digestion, but also as a pulsating organ acting under the control of nerve centres in the medulla. That the various ascertained normal functions of this viscus may be vicariously performed by others, as shown in animals from which it has been completely extirpated, does not contradict the occurrence of actual disease in the organ, nor the baleful influence of certain of its diseases on the system at large.

ANÆMIA OF THE SPLEEN.

General anæmia, debility, wasting diseases, starvation, hæmorrhage, stimulus to formation of red globules, asphyxia, electricity, cold, quinine, eucalyptus, ergot. Symptoms: lack of eosinophile leucocytes in the blood of a debilitated subject may lead to suspicion. Treatment: tonic, light, sunshine, pure air, exercise, nutritive food, iron, bitters.

In cases of general anæmia the spleen is liable to be small, shrunken, wrinkled, and when cut the surface is drier and lighter colored than in the normal condition. This condition may be seen after old standing debilitating diseases, but is common in animals that have been reduced by starvation, just as the opposite condition of hyperæmia and enlargement comes of abundance of rich food and an active digestion. It may shrink temporarily as the result of profuse hemorrhage, but Bizzozero and Salvioli found that several days after such loss of blood it became enlarged and its parenchyma contained many red nucleated hæmatoblasts. The result of hemorrhage is therefore to stimulate the organ to enlargement and to the resumption of its embryonic function of producing red blood globules. Contraction of the spleen further occurs under asphyxia, the deoxidized blood being supposed to operate through the medulla oblongata. As already noted the spleen shrinks under stimulation of the central end of a sensory nerve (vagus, sciatic). An induced current of electricity applied to the skin over the spleen causes marked contraction (Botkin). Cold, quinine, eucalyptus, ergot and other agents also induce contraction. In the normal condition there is an inverse ratio between the bulk of the spleen and the liver, the enlargement of the one entailing a diminution of the other, but in certain diseased states, such as anthrax, ague, etc., both are liable to enlargement at the same time.

Symptoms of splenic anæmia are wanting, through a lack of eosinophile leucocytes, in the blood of a starved or otherwise debilitated animal, may lead to suspicion of the condition.

The treatment of such a case would be addressed rather to the general debility which induced the splenic contraction than to the contraction itself. Light, sunshine, pure air, exercise, grooming, nourishing food and the avoidance of all debilitating morbid conditions would indicate the principles of therapeutic management.

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.