6.10.4 Jugular vein thrombosis
Occlusion or partial occlusion of the jugular vein by a thrombus is a relatively common complication of long-term catheterisation (>24 hours). Usually the thrombus is small and does not present a clinical problem other than complithe administration of intravenous fluids or drugs. However, in some cases the situation becomes more serious. The vein may become inflamed (thrombophlebitis) or even infected. This may occur following intravenous injection of irritant drugs, poor aseptic technique, or simply due to the presence of foreign material such as a catheter. It is most commonly a problem in anirecovering from colic surgery and in those with septicaemia, endotoxor bacteraemias (particularly salmonellosis). This is because these animals are frequently in a hypercoagulable state and are usually catheterised for prolonged periods. In severe cases, the condition can be life threatening and complications such as pulmonary thrombo-embolism and endocarditis can occur. Long-term scarring of the vein may result in reduced venous return, although recanalisation usually results in resolution and a collateral circulation may develop over time.
Palpation of the affected vein reveals a firm cylindrical mass within the lumen. Distension of the vein above the thrombus will be present to varying degrees depending on how much of the lumen is occluded. Oedema and venous disof the head may be visible if the vein is severely occluded, particularly if both left and right jugular veins are affected. Swelling can become marked and is usually worse after exercise. Athletic performance can be reduced due to preson the pharynx. Pain, heat and swelling around the site may be present with thrombophlebitis; if the site is infected a discharge may break out at the skin surface.
Diagnosis can be made on clinical grounds. In addition, ultrasonography is a valuable technique which allows the clinician to detect the build up of thrombus within the lumen before it becomes clinically apparent. It will show a moderechogenic mass within anechoic blood filling the vein and allows the size of the thrombus to be measured. Slow flowing blood may appear to contain echogenic particles similar to the smoke occasionally seen in the heart (see section 4.2.6). Pockets of fluid may be seen within the thrombus and hyperareas suggestive of gas may be found in thrombi which are infected. Recanalisation may become visible as the thrombus matures and the condition resolves.
Haematology and plasma fibrinogen analysis are useful aids if infection is considered possible, but interpretation is frequently complicated by the primary problem for which the animal was under treatment.
If a substantial thrombus is detected, indwelling catheters should be removed. Further catheterisation or intravenous injections in the affected vein should be avoided if possible. However, if the thrombosis is small and uninfected, it may be better to place catheters in the same vein lower down rather than risk losing both jugular veins. Alternative sites should be used if possible for taking blood sample or administering intravenous injections. The lateral thoracic, cephalic and saphenous veins are suitable. If sepsis is suspected, the contents of catheters should be submitted for bacteriological culture and isolates should be tested for antibiotic sensitivity. Broad spectrum antibiotic treatment is indicated until the results are available. Local poulticing may help to bring an abscess to a head. NSAIDs may reduce the inflammatory response and prevent further aggregation of thrombus.
Most cases of jugular thrombosis resolve without complication. However, the prognosis is not so good if marked thrombophlebitis is present, or if infection develops. Long-term antibiosis may be required for infected thrombi. In intractable, severe cases, surgical resection of the affected vein is required.