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.