The dreaded consequence of injections – phlebitis

Phlebitis is an inflammatory change in the vein wall. In horses, the jugular veins, which are located on either side of the neck in the jugular groove, are often affected. These veins transport blood from the head to the heart. Due to their location and easy accessibility, they are most commonly used for injections, infusions, or the insertion of intravenous catheters.

INHALT
Definition Causes and development Symptoms Diagnosis Treatment Forecast Prophylaxis
Definition

Different types of vein inflammation are distinguished based on the structures of the vein affected. Endophlebitis refers to inflammation of the innermost layer of the vein wall. Periphlebitis, on the other hand, is inflammation of the tissue surrounding the vein. Thrombophlebitis, which occurs relatively frequently in horses, describes inflammation of the vein wall with the formation of a thrombus (blood clot).

Causes and development

Phlebitis can be aseptic (without the involvement of pathogens) or septic (with the involvement of pathogens).

Every injection into a vein, even when performed correctly, causes mechanical irritation at the injection site, resulting in localized aseptic inflammation within 24 to 48 hours. However, this inflammation subsides within 2 to 3 days without treatment. Repeated use of the same vein can cause a blood clot to form on the inner wall, which gradually grows larger and makes the vein increasingly impermeable. This is known as aseptic thrombophlebitis.

Septic thrombophlebitis is caused by failure to disinfect the puncture site, unclean, non-sterile syringes and cannulas, or non-sterile or irritating injection or infusion solutions. Bacteria enter the vein through the puncture site and cause purulent inflammation of the vein wall with the formation of a purulent blood clot.

Periphlebitis is caused by improper or accidental injections into the tissue surrounding the vein. This can happen especially when the horse makes defensive movements. The injected drugs or fluids irritate the connective tissue, which can also be aseptic or septic. In the septic form, abscesses form and drain pus to the outside.

Symptoms

Often, the first symptom is a cord-like, sometimes warm thickening in the area of the vein puncture site. Aseptic thrombophlebitis manifests itself as a thickened but painless vein.

In the case of septic thrombophlebitis, the affected vein is severely thickened over a length of approximately 20 cm or more, hard, warm, clearly painful, and no longer compressible. Due to the impermeability of the vein, congestion and swelling in the head area, up to and including a hippopotamus head, can occur because the blood cannot be transported away. As the condition progresses, abscesses and necrosis (death) of the entire vein may occur.

A life-threatening complication of this vein inflammation is the washing away of infected thrombus material. The pathogen is spread throughout the entire organism via the blood and can thus lead to infection of other organs such as the lungs, kidneys, or joints.

In the case of periphlebitis, extensive swelling occurs in the area surrounding the vein, which often leads to fatigue and fever if bacteria are involved.

Diagnosis

After a thorough clinical examination and a preliminary report on any injections administered, your veterinarian will usually be able to make a diagnosis quickly. With the help of an additional ultrasound examination, they can determine the exact extent of the changes within the vein and make precise statements about the permeability of the vein.

Treatment

Mild vein inflammation without thrombus formation usually heals on its own within a few days; treatment is not necessary. Aseptic inflammation with thrombus formation is treated locally several times a day for several days with anti-inflammatory ointments or gels. Your veterinarian will decide on a case-by-case basis whether anticoagulant medication should also be used to dissolve the blood clot and restore blood flow in the vein. In severe cases, hospitalization may be necessary to better monitor the patient.

In cases of septic vein inflammation, ointments that promote blood circulation are applied. The aim of this treatment is to allow any abscesses that have formed to mature so that they can then be lanced and the pus drained out. The horses are also treated with antibiotics to prevent the bacteria from spreading through the blood. It is recommended that this treatment be carried out in an animal hospital.

IMPORTANT: Ointments must NOT be rubbed into thrombosed veins, but only applied to the surface, as there is a risk that parts of the thrombus could detach and spread through the bloodstream.

If the vein is no longer patent in the case of infected thrombophlebitis and its function cannot be restored, it is possible to remove the entire vein surgically. The advantages of this operation, known as phlebectomy, are a faster healing process and the prevention of infected thrombus material being washed away.

Forecast

Simple cases of phlebitis have a good prognosis, as they usually heal without treatment. Phlebitis with uninfected blood clots has a significantly longer healing phase, but still has a favorable prognosis, as the blood clots usually dissolve completely. Infected phlebitis can take a very long time to heal with conservative treatment, sometimes lasting several months. Due to the potential loss of the affected vein, the prognosis is considered cautious. After surgical removal of the inflamed vein, healing takes only about three weeks. The function of the removed vein is taken over by other nearby vessels.

Prophylaxis

Phlebitis cannot be completely prevented. However, the risk of inflammation can be significantly reduced with the help of various measures. The most important measures within the scope of veterinary examination and treatment are careful disinfection, the use of sterile materials, and the correct and careful administration of any intravenous injection or infusion. In clinics in particular, consistent management of indwelling venous catheters, including the correct selection of the catheter system, care, monitoring, and timely replacement, is one of the most important measures for preventing vein inflammation.