CHAPTER IV.
DISEASES OF BLOOD-VESSELS.
Diseases of vessels, arteries or veins, in animals of the bovine and ovine species are frequently nothing more than localisations of grave general disorders, and rarely admit of treatment. This is specially the case in regard to arteries, but a study of the diseases of veins has some practical importance.
PHLEBITIS.
Phlebitis, i.e., inflammation of a vein, is of interest only in the case of bovine animals. In them certain conditions may occur which the practitioner should understand, with a view either to prevention or treatment. Inflammation of the veins may be due to external causes, such as surgical or accidental wounds (phlebotomy wounds, accidental wounds, local inflammations, etc.), or to internal causes of infectious origin (general infection, puerperal infection, etc.).
ACCIDENTAL PHLEBITIS.
The jugular vein may become inflamed as a result of accidental wounds or of phlebotomy, but the mammary vein in cows is much more frequently affected. In both cases the disease is due to infection of the clot which seals the vessel; it may assume the form of either adhesive phlebitis or suppurative phlebitis. Whether produced directly by the use of infected instruments or whether it is of a secondary character, traceable to the clot being infected by germs entering from without being conveyed to the wounds by the head-stall chains, by litter, manure, etc., the result is the same. The inflammation, at first confined to the endothelium, extends to the wall of the vein and causes fibrin to be precipitated over the inner wall of the inflamed vein for a distance varying with each case.
If the microorganisms do not produce suppuration, the vein appears simply thrombosed and inflamed, the phlebitis remains of an adhesive character, and may disappear spontaneously, provided the animal be kept quiet. If, on the other hand, suppuration is set up, the clot gradually breaks down, the internal surface of the vein develops granulations and undergoes suppuration, and the phlebitis is then said to become suppurative. The clot may even become entirely detached, transforming the suppurative phlebitis into a very grave form of hæmorrhagic phlebitis.
The jugular is the commonest seat of adhesive phlebitis, the mammary vein of suppurative phlebitis.
Symptoms. The symptoms are easy to recognise. The accidental or instrumental wound is the seat of a painful œdematous swelling. It discharges a reddish offensive serosity, or exhibits blackish-violet bleeding granulations surrounding a little central sinus.
The affected vein, whether the jugular or mammary, soon becomes swollen, is sensitive to the touch and very rapidly becomes indurated in the direction of its origin for a greater or less distance.