Inflammation of the Superficial Veins in Cats


PetMD Editorial

Updated Aug. 24, 2022

Phlebitis in Cats

Phlebitis is associated with a condition known as superficial thrombophlebitis -- an inflammation of veins close to the surface of the body, also known as the superficial veins. Phlebitis is generally due to an infection, or because of thrombosis -- the formation of a clot (or thrombus) inside a blood vessel, which in turn obstructs the flow of blood through the body.

Superficial venous thrombophlebitis is the most common form of this condition, and is usually localized in one area.

Deep tissue thrombophlebitis, conversely, is associated with clinical signs of sepsis, in which a bacterial infection occurs due to the presence of pathogenic organisms and their toxins in the blood or tissues. This type of thrombophlebitis is also associated with deep tissue thromboembolism, in which a clot or thrombus formed in one part of the body breaks free and migrates to another blood vessel, where it causes blockage.

Phlebitis can affect both dogs and cats. If you would like to learn more about how this disease affects dogs, please visit this page in the PetMD health library.

Symptoms and Types

The main symptom of phlebitis is a localized inflammation, which can be seen due to warmth, swelling, pain, hardened vessels, or a redness of the skin known as erythema. If at least two of the aforementioned signs are present, this can be taken as a sign of local inflammation. Drainage or fever may also be present, both being associated with such infections.


There is no age, breed, or gender of cat that is known to be more susceptible to the development of phlebitis. However, very young or elderly cats may be at higher risk simply due to a less developed or poorly functioning immune system.

Characteristics that are considered risk factors for the development of phlebitis include obesity, lack of mobility, poor vein quality, chronic heart or kidney disease, pregnancy, and/or an immunodeficiency disorder in which the cat's immune system does not function properly.

The main cause of phlebitis is intravenous (IV) catheter use. Poor catheter quality or care may lead to bacterial colonization of a catheter, which can then infect the cat. Catheters are often used during surgery, or for the treatment of trauma victims.


A number of diagnostic procedures are necessary for properly diagnosing phlebitis. The Doppler test is an inexpensive means for testing blood flow in the cat's veins, and may reveal any blood circulation irregularities and blockage. Blood cultures may also indicate signs associated with systematic inflammations. Additional diagnostic techniques may include X-ray imaging and urine analysis.


If infection is suspected, antibiotic treatment will be the most likely treatment. The specific antibiotic prescribed for your cat will depend on the location of the infection, as well as the suspected contaminants behind the infection (if no culture is available at the time). Additional medications may help to make your cat more comfortable by alleviating related symptoms.

Living and Management

After the initial treatment, antibiotic therapy should be adjusted based on the follow-up culture tests. Certain veins, known as phlebotic veins, should be avoided for IV therapy or blood collection until your cat has completely healed. With proper antibiotic treatment, the most severe cases may still take up to three weeks to resolve.


Because the main cause of phlebitis is poor quality catheters or improper catheter care, this is the primary area to target when thinking about prevention. Any IV catheter sites should be cleaned regularly with antimicrobials and treated with antimicrobial ointment, in order to avoid bacterial infection that may lead to phlebitis. Sterile dressings should be used, and catheters should be changed within 24 hours, especially if they were placed in an emergency situation. Longer catheters may reduce the incidence of phlebitis.

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