As already noticed, thrombosis of the jugular vein was a disease of common occurrence in the days of indiscriminate blood-letting and unclean surgical practice as pursued before the advent of antiseptic surgery when phlebitis frequently followed the operation. In more recent years, since the lancet and the fleam have been laid aside, it has become a rare and exceptional ailment.
As in arteries, so in veins, thrombosis is the result of degeneration or injury inflicted on the wall of the vessel. It also results when the vessels become varicose or abnormally dilated. In the particular instance under consideration it follows upon the operation of bleeding, or the accidental opening of the jugular vein. But the immediate cause is not perhaps the injury alone, but the introduction into the wound at the time, or subsequent to its occurrence, of some septic or decomposing matter. A dirty fleam or lancet, a dirty pin, or dirty tow employed to bring the edges of the divided vessel together, are the most likely media by which to infect the wound. Inflammation of the vessel having been thus excited, the blood circulating within it is induced to coagulate, and to be deposited on the inflamed surface layer after layer until the passage becomes completely obstructed and the flow of blood along the neck on the affected side is arrested in its course towards the heart.
The lips of the wounded vessel are more or less tumefied and separated from each other, and the parts around are swollen and painful to the touch. The plugging of the vessel invariably proceeds in an upward direction, where it may be felt for some distance as a hard, cordlike thickening in the channel of the neck. Subsequent changes in the condition of the vessel and its contents will depend upon circumstances. In some instances the wound heals, the plug becomes organized, still retaining its position in the vein, with which it unites to form a solid cord. Here the general health of the patient is but little impaired; since, however, the jugular vein is no longer able to convey the blood back from that side of the head to the heart, the vessels of the face will be inordinately distended, the brain will be somewhat surcharged with blood and liable to slight functional disturbances, especially when the head is held in a depending position. This danger will be materially modified after a time, when compensating enlargement of the jugular vein of the opposite side and its tributaries takes place, and their carrying capacity becomes thereby increased.
It must be understood that with one jugular vein spoilt the conveyance of blood from the head to the heart will have to be done for the most part by the other, which, in course of a little time, will widen out and accommodate itself to,the task imposed upon it.
Animals having suffered from this disease should not be turned to grass or allowed to eat from the ground. The downward position of the head under the altered conditions of the circulation tends to an accumulation of venous blood in the vessels of the head, resulting in swelling of the lips and tissues of the face, dizziness, and vertigo.
Instead of being organized, the plug in the vein may soften and break up into a pus-like matter, resulting in the formation of one or more abscesses in the upward course of the swelling. These may break, empty themselves, and heal, perhaps to form again and produce deep sinuous wounds in the track of the vessel. The most serious consequences resulting from jugular thrombosis occur when matter from the softened and disintegrated clot finds its way into the circulation. Thereby the blood becomes poisoned. The septic particles are distributed over the body, and, settling down in some of the more important organs, produce destructive abscesses or a condition known as " pyaemia".
Any appearance of thickening in the course of the jugular vein, such as we have described, should be met by prompt measures of treatment. A dose of physic will first be called for, and at the same time all hard corn is to be knocked off and replaced by sloppy mashes of bran and scalded chaff. The wound should be repeatedly irrigated by carbolic solution and covered with antiseptic gauze. Hot fomentations applied over the injured vein will aid in reducing inflammatory action and checking the progress of the disease when permissible. Should abscesses form, they will require to be opened, and to be well syringed out with antiseptic dressing from time to time and packed with antiseptic wool.
Some practitioners recommend a blister to the swollen vein, and place complete reliance on this form of treatment. There can be no doubt that in some subacute and slowly progressive cases such a course might prove beneficial, but in the more active and severe attacks the course recommended above would be more appropriate.