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EQUINE VETERINARY EDUCATION / AE / APRIL 2018


developed haematogenous septic arthritis from a jugular vein septic thrombophlebitis. Thrombophlebitis is defined as venous thrombosis


secondary to inflammation of the vessel wall. Jugular thrombophlebitis is a commonly observed, undesirable, iatrogenic complication seen in equine practice, particularly during intensive care (Dias and de Lacerda Neto 2013). It occurs almost exclusively at the site of placement of an i.v. catheter and in colic cases it has been estimated to occur in 2 to >50% of catheters left in situ >48 h (Lankveld et al. 2001; Geraghty et al. 2009; Klohnen 2009; Russell et al. 2010). The condition may progress to life-threatening complications and reported complications of septic thrombophlebitis in horses include bacteraemia, endotoxaemia, vegetative endocarditis, pulmonary thromboembolism and pleu- ropneumonia via the pulmonary circulation (Ryu et al. 2004; Dolente et al. 2005; Dias and de Lacerda Neto 2013). The aetiological triad of venous catheter-related


thrombosis consists of local trauma, venous stasis, and altered coagulation status, the most important of which is local, ongoing injury of the jugular vein caused by the catheter (Lankveld et al. 2001). Horses particularly at risk are critically ill patients with severe gastrointestinal disease, septic foals and mature horses subjected to severe systemic inflammatory response syndrome, severe intestinal disease, endotoxaemia, salmonellosis or hypoproteinaemia (Dallap Schaer and Epstein 2009; Dias and de Lacerda Neto 2013). These disease processes are also known to be associated with the development of a general hypercoagulation state, which is believed to be attributable to the loss of specific anticoagulant proteins such as protein C and antithrombin III (Dolente et al. 2005). The degree of debilitation of the horse is also an important predisposing factor for the occurrence of thrombophlebitis caused by an i.v. catheter (Dolente et al. 2005; Dallap Schaer and Epstein 2009). Silastic catheters are known to be the least thrombogenic of all catheters used in veterinary medicine (Dolente et al. 2005). Nevertheless, catheter composition does not seem to be a risk factor for the occurrence of thrombosis in horses (Lankveld et al. 2001). The diagnosis of thrombophlebitis is based primarily on


history and physical signs, principally localised firmness and a cord-like jugular vein (Dias and de Lacerda Neto 2013). When bacteria become seeded in thrombi to produce a septic thrombophlebitis, affected horses can show fever, depression and neck stiffness. Other clinical signs include local swelling, and heat and pain around the cord-like jugular vein. The disease can be evaluated using ultrasonography and/or contrast angiograms. The sonographic feature is a thick- walled vein with an occlusive hyperechoic structure adhering to the vessel wall (Geraghty et al. 2009). A septic thrombus typically appears as a hyperechoic heterogeneous cavitating mass in which the anechoic areas represent fluid accumulation secondary to infection and necrosis. Anaerobic bacterial infections often show numerous hyperechoic areas, which creates an acoustic shadow due to gas production (Dias and de Lacerda Neto 2013). Both medical and surgical treatments for thrombophlebitis


are reported. Local treatment with hot packs and hydrotherapy can be useful while nonsteroidal anti- inflammatory drugs may help to reduce pain and inflammation. Systemic antibiotics are indicated for sepsis and heparin therapy may be useful for generalised coagulopathy


© 2016 EVJ Ltd


(Dallap Schaer and Epstein 2009; Dias and de Lacerda Neto 2013). Aspirin at a dose of 20 mg/kg bwt every other day is also recommended to inhibit platelet activation and aggregation (Dias and de Lacerda Neto 2013). Other novel medical treatments using thrombolytic agents such as streptokinase, urokinase and tissue plasminogen activator have also been investigated (Morton 2005). Thrombolytic therapy consists of the pharmacological dissolution of the blood clot by i.v. infusion of the plasminogen activators to activate components of the intrinsic fibrinolytic system. However, further research is needed in horses when using these new fibrinolytic agents (Dias and de Lacerda Neto 2013). Surgical therapies for restoration of blood flow, which include balloon thrombectomy and a variety of vein transplantation techniques for replacing affected portions of the jugular with different types of graft, are typically ineffective and may only be achieved with complex and expensive procedures (Wiemer et al. 2005; Russell et al. 2010). In refractory cases, surgical excision of the vein has been recommended and recently, standing jugular phlebotomy for removal of septic contents has been reported (Russell et al. 2010). In the present case, surgical intervention was required after all medical treatment avenues had been exhausted. The standing phlebotomy technique was chosen since it had been reported to be a straightforward procedure with minimal post-operative complications (Russell et al. 2010). Fortunately, the athletic performance of horses used for


nonracing events is not affected by thrombophlebitis, whether it is unilateral or bilateral (Moreau and Lavoie 2009). In bilateral cases, the lateral thoracic, cephalic and saphenous veins are other options for drug administration and the collection of venous blood samples (Dias and de Lacerda Neto 2013).


Ethical animal research We have explicit informed consent from the animal owner.


Source of funding None.


Authors’ declaration of interests No conflicts of interest have been declared.


Authorship


All authors have provided a substantial contribution to the manuscript and approved the final version.


Manufacturers' addresses 1Uvedo, Jordan. 2Gulf Pharmaceutical Industries, Ras al Khaimah, United Arab Emirates. 3Bimeda, Inc., Le Sueur, Minnesota, USA. 4Randlab, Peakhurst, New South Wales, Australia. 5Pfizer Animal Health, Kalamazoo, Michigan, USA. 6AstraZeneca UK Limited, London, UK.


References


Carstanjen, B., Boehart, S. and Cislakova, M. (2010) Septic arthritis in adult horses. Pol. J. Vet. Sci. 13, 201-212.


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