◊ Affections Of Blood Vessels ◊
Affections Of Blood Vessels
I-AFFECTIONS OF ARTERIES
It is non-significant injury as a result of elasticity and vitality of the artery. When an artery is severed by contusion, the inner and middle coats contract and retract within the outer coat, and this promotes thrombus formation.
i-Penetrating or non-penetrating: -
Non-penetrating wound causes weakness of the vessels wall predisposing to aneurism while penetrating one causes hemorrhage. Severity of hemorrhage depends on size of injured artery.
ii-Punctured, incised, contused, or lacerated: -
a-Punctured wound: -
It may be caused by sharp pointed objects, a piece of bone during fracture, or during surgery (neurectomy or phlebotomy) and gravity of the wound depends up on;
1-The nature of the causative object
2- The size of the puncture
3-The location and the size of the artery
b-Incised wound: -
1- Incised - Complete severing: -
Complete severing of large vessel may cause fatal hemorrhage, while those with smaller caliber, deeply situated, and associated with narrow wound in the overlaying tissue, may be followed by natural hemostasis with thrombus formation that is organized 40 days later.
Before organization of the thrombus, hemorrhage may recur if the wound is subjected to violence or the blood pressure increased.
2- Incised - Partial severing: -
Partial severing of the vessel may be oblique, transverse, or longitudinal. If the oblique or transverse sections are small, spontaneous hemostasis may occur as in case of punctured wound. If more than half the circumference of the vessel is involved, the wound retracts due to the elasticity of the wall and the constant force of the blood stream prevents the formation of thrombus. On the other hand, longitudinal wounds are less gaping, and so it is not so dangerous.
When an artery is torn, the inner layers recoil and covered by the outer layer that promotes coagulation, and this is the main idea of hemostasis by torsion or ecraseur.
Characteristics of arterial hemorrhage: -
1-The blood escapes in jets that coordinate with the ventricular contraction, but if the artery is so deep, the pulsatile movement may be not clear.
2-The blood is bright red
3-The bleeding is dimensioned or arrested by pressing the cardiac side of the wound, and when bleeding continues, it may be due to anastomosis with another artery at the distal portion.
Varieties of hemorrhage:-
1-Primary or immediate hemorrhage
2-Recurrent or intermediary or reactionary hemorrhage
Prognosis of arterial wounds: -
Prognosis depends up on the size of the wound, the species of the animal (hemostasis occurs faster in dog, ox, sheep, and horse respectively), and the nature of the injury (complete severing is better than partial severing of the artery, as the inner wall retract in the former controversial to the later).
Treatment of arterial wounds directed towards;
1-General treatment of the associating wound by suturing …..etc
2-Control of infection and stimulation of healing by using antibiotic and vitamins
3-Control of hemorrhage
2-Ulceration of Artery
The wall of an artery can be subjected to ulceration by the pyogenic microorganisms as with abscess formation and fatal bleeding can occur depending up on the caliber of the vessel.
1-Treatment of the associating cause (The abscess)
2-Control of hemorrhage
3-Rupture of Artery
Artery may rupture as a result of laceration by fractured bone or violent effort as struggling or jumping.
When a superficial artery ruptures, subcutaneous pulsating hematoma beneath the skin ensues (diffuse aneurism), but when a large internal artery ruptured, death may occur within few minutes to hours according to the size of the artery.
Small superficial ruptures treated as hematoma, while internal ruptures are usually out of treatment.
Aneurysm is seen frequently in horses as a result of strongylus vulgaris. External aneurism is distinguished as a pulsating swelling on the course of an artery that expands at each pulsation. The main complication of an aneurism is rupturing with fatal hemorrhage.
Ligation of the artery above and below the aneurysm and extirpation of the aneurysm after ligation
5-Arteritis and Arterial Thrombus
Arteritis always precedes thrombosis. It ensues as a result of irritation of the endothelium by bacteria or parasite, or by violent over stretching of the endothelium. The rough surface of the artery permits thrombus formation that starts small and later on increases in size and extends to the first collateral branch and causes complete occlusion.
Partial thrombus affects the need of the tissue to blood and oxygen, even if the animal doesn’t suffer any clinical signs, but when the animal is active, the blood supply becomes relatively insufficient and signs of reduced blood supply to that organ appear clearly.
An example of this theory is the colic seen in equine after feeding them coarser roughages while they have mesenteric thrombus due to strongylus vulgaris. These animals will suffer from colic as the blood supply of the intestine is relatively insufficient during digestion of coarse roughages that require relatively much more intestinal motility and subsequently much more blood supply.
Symptoms of aortic and ileac thrombosis: -
The symptoms of thrombosis at bifurcation of the aorta are characteristic, the horse is quite normal at rest, but after exercise, he stops and shows symptoms of distress and even the animal may lying down. If the case is unilateral, the affected limb may be cold and has no prominent veins like the health leg, and the condition is called intermittent claudication. On rectal examination, the location of the thrombus can be detected. The prognosis is grave because the case is usually incurable.
There is no satisfactory treatment of the condition, and the following measures are tried without definite success;
1-Administration of potassium iodide, fibrinolytic enzymes, or heparin
2-Massage of the aorta per rectum although fragmentation of the thrombus may cause embolism and death of the animal
3-Rest of the animal that is followed by gradual exercise
II-AFFECTIONS OF VEINS
Wounds of the vein are much more common than arterial ones as a result of the superficial location of veins, and they usually give rise to hemorrhage of various degrees according to the size of the vein wound, aside from the hemorrhage, infection of the vein and phlebitis may ensue according to the nature of the causative agent.
As arterial one
When a vein is opened near the chest, air can enter the vein leading to air embolism, that may affect the coronary artery, pulmonary artery, or it cause heart failure when it is large enough.
Massage over the injured vein to permit escape of air with blood
Phlebitis is irritation of the smooth inner lining of a vein (tunica intima) and associated with roughening of the vein lining that can encourage the formation of clots. All veins are susceptible for phlebitis, however, the jugular and umbilical veins are usually at greater risk of developing phlebitis.
General signs: -
The vein is reddened or inflamed and can sometimes be felt as a thick cord beneath the skin.
1-Peri-vascular infiltration by irritant drug like chloral hydrate or thiopental
2-Lack of aseptic precautions during IV injection
3-Extension of infection from other sites, septic wounds over the vein, or toxins
4-Infection of umbilicus
The vein appears as hard resistant cord due to roughening of the endothelium with thrombus formation that adheres to the wall of the vein occluding its lumen partially or completely. The peri-venous tissue seems edematous and pain is evident along the course of the vein.
Treatment includes resting, antibiotics and anti-inflammatory drugs
1-Keeping the affected area at rest to avoid extension of the inflammation or disintegration of the thrombus and embolism
2-Application of antiseptic for the wound of the affected vein
3-Providing for drainage of the wound
4-Application of counter irritant after the thrombus organized, to stimulate collateral circulation and to remove edema from the parts drained by the vein
Inflammatory symptoms are much more acute, and abscesses may be formed over the vein that may form fistula discharging hemorrhagic pus. Probing of the fistula may cause the probe to enter the vein.
1-Opening abscess after maturation and enlarging the fistulous orifice for removal of the necrotic tissue
2-Irrigation of the lesion by antiseptics
3-Otherwise, extirpation of the purulent vein can be performed
It is a complication of one of the fore-mentioned types of phlebitis that ensues due to disturbance of the clot or the thrombus of the vessels either mechanically or as a result of infection. It is characterized by repeated hemorrhage.
1-Plugging of the wound with antiseptic gauze to arrest bleeding
2-Ligation of the vein
It is uncommon in veterinary practice. Usually it is observed on the ventral aspect of the abdomen or the lower part of the leg.
2-Firing the skin over the vein to act as a sort of permanent bandage
3-Obliteration of the vein by injection with certain substances
4-Ligation of the vein above and below the swelling and excision can be applied