Of direct traumatism may be mentioned an aneurism of the arch of the aorta in a horse struck by a wagon pole, during a sharp descent (Jacob), and two with aortic aneurism after violent blows on the back with shafts of wagons.
Symptoms. An aneurism within reach of the hand is to be recognized primarily by the pulsation of the swelling synchronously with the beats of the heart, and by a double rushing sound with each beat of the heart, observed on auscultation. An abscess over a large artery lying on a bone may pulsate but it is to be distinguished by the presence of a single in place of a double rushing sound on auscultation, by the possibility of causing more or less complete collapse under pressure, and by the history of an active phlegmonous inflammation followed by softening which steadily extends from the centre of the previously dense mass. In a case of aneurism of the gluteal artery of the horse reported by King and in one observed by the author the symptoms were unmistakable. Other similar examples on the popliteal artery and other failed to be recognized during life though attended by lameness.
In internal aneurism the symptoms are mostly indefinite. Ollivier found tympany and vomiting in a goat which at the necropsy showed an aneurism of the anterior aorta as large as the closed fist and enclosing a sewing needle. A more careful diagnosis should have detected a retarding of the maxillary pulse and a double rush over the carotid with each beat of the heart. Pressure on the vagus doubtless led to the symptoms noticed. In aneurism of the posterior aorta there have been noticed a loss of life and energy, dulness, lack of appetite and stiffness of the loins. Torpor of the bowels, expulsion of fæces with effort and groaning, intermittent colics, lameness in one or both hind limbs, and finally cramps in the hind limbs, and palpitations. In one case Maillet was able to reach the aneurismal tumor through the rectum.
Treatment. The treatment of internal aneurism will be seldom called for in the lower animals, as the disease is seldom diagnosed, is beyond reach of mechanical applications, and survival without certain power of endurance would seldom be desirable. In some valuable breeding animals it might be worth while to seek prolongation of life. The most promising measures are absolute rest, and low, non-stimulating diet of a laxative nature and in small bulk. Iodide of potassium is often useful in man, and although in the lower animals there is not the excuse of specific disease, yet the rest to the circulation and reduction of blood tension are not to be undervalued. Bromides may be given with the same object.
Other measures applicable only to aneurisms, within reach and essentially of a surgical nature include: Ice bags and compression. The compression should as a rule begin at the distal end of the limb and be concentrated by suitably shaped pads on the swellings. Ligature of the diseased artery above or below or both above and below the tumor. Galvano-puncture of the aneurism with the object of inducing coagulation. The introduction of coils of fine wire through a hypodermic needle with the same object in view. In both horse and dog the persistent compression with the finger seconded as it is by the plasticity of the blood has succeeded in checking the flow from large arterial orifices, and offers great encouragement in the application of this measure to aneurisms. The injection into the sac of tincture of chloride of iron with firm compression to prevent motion of the blood is another available resort.
ARTERIO-SCLEROSIS.
Fibrous thickening of the arterial coats and calcification are well known lesions in the posterior aorta particularly of the horse. Commencing in congestion or degeneration which lessens the resistance of the vascular walls, the condition tends to dilatation, and if this is checked by compensatory thickening, the condition of sclerosis is induced. The combination of a slight fusiform dilatation and fibrous or calcareous sclerosis is well known in the posterior aorta of the horse. Unless it advances to marked aneurismal dilatation the condition is not often recognized. If diagnosed, rest and quieting of the circulation are especially indicated. Should it occur in other parts of the body the symptoms would correspond to the organ invaded.
ANGEIOMA. CIRCOID ANEURISM. ANEURISM BY ANASTOMOSIS. VENOUS TUMOR. NŒVUS.
These are forms of dilatation and elongation of the network of small arteries, or veins, and even of the intervening capillaries. In man these constitute the unsightly red patches and swellings that appear on the face and hands. In animals with dark skins and hairy covering they can only be recognized by the swelling, the feeling as of a bag of worms when the hand is passed over it, and by the rushing sound when auscultated. The trouble is usually subcutaneous and is essentially a surgical one. The most promising treatment is by persistent pressure, by electric current supplementing the pressure, by electro-puncture, and by injections of muriate of iron. When the nœvus is not too extensive a double thread drawn by a needle through beneath the tumor at short intervals, then cut and each point tied separately, so as to completely stop circulation is most effective.