Inflammation of the veins is a medical condition known as phlebitis. This condition results in inflammation and swelling in and around the affected veins. It can happen to superficial or deep tissue veins and can affect any part of the body. Phlebitis can affect cats of any age or breed. It is common in animals that have immune disorders or reduced immune function. Vein inflammation is often associated with thrombosis or blood clots. It is also commonly caused by infections. Inflammation of the veins can affect blood flow throughout the body, which may result in complications with key bodily systems like the cardiac, respiratory, and nervous system. Cats with symptoms of inflammation of veins should be seen by a veterinary professional as soon as possible.

The most common symptom of inflammation of the veins in cats is inflammation or swelling, often in a localized area. It is possible for the inflamed veins to swell so much that they can be felt or seen through the skin. Additional symptoms are common but may vary depending on the location the inflammation. Vein inflammation can affect the cardiac, respiratory, or other systems. 

Symptoms include:

There are two primary types of inflammation of the veins in cats, although in many cases phlebitis will be named for its location in the body. The two types of vein inflammation are:

A variety of conditions can cause inflammation of veins. Any inflammatory condition can include veins or blood vessels. It is also commonly caused by blood clots, sources of infection, or as a complication associated with wounds or surgeries. The cause of the inflammation can affect a localized area within the cat’s body or may be a septic, or full-body, condition. Common causes of phlebitis in cats include:

Diagnosing inflammation of veins is a simple enough task, but diagnosing the underlying cause may require the use of multiple diagnostic methods. Your veterinarian will need to discuss your pet’s full medical history, including any medications or recent medical procedures. Be prepared to discuss any symptoms you have observed as well. A complete physical exam will allow your veterinarian to locate inflamed veins, swelling, wounds, or hot spots. Veterinary staff will also take samples of your pet’s blood and urine for laboratory analysis. Blood tests will include a complete blood count, biochemistry panel, and blood culture to look for signs of infection. A urinalysis and urine culture may also be conducted. 

Additional diagnostic measures may be needed, especially if an obvious cause like a bacterial infection is not identified. X-rays, CT scans, or other diagnostic imaging techniques may be used. These methods will allow your veterinarian to observe the veins in the affected area, image the heart and lungs, and check for signs of certain underlying causes like blood clots or cancers. CT angiography, a method that uses dye to highlight veins and locate clots or blockage, is also common when vein inflammation is present. In some cases, an echocardiogram may also be used to study heart performance. If signs of cancer or growths are identified, a tissue biopsy may be collected as well.

Many of the treatments associated with phlebitis in cats are used to treat the underlying cause of the condition. This means the prescribed treatments may vary significantly depending on the diagnosed cause. Some of the treatments for inflammation of the veins include:

Intravenous (IV) fluids are often administered to patients experiencing inflammation. This therapy can aid in maintaining proper hydration, supporting cats that are in a weakened state, and helping with blood flow. This common treatment carries a very low risk and is generally administered on an inpatient basis. 

Oxygen Therapy 

With blood clots, especially those causing respiratory symptoms, oxygen will be provided to improve the blood oxygen level and stabilize the cat. Oxygen may be administered using tubing, masks, or an oxygen cage. This therapy is also low-risk and provided on an inpatient basis. 

Anti-inflammatory Drugs 

This category of drug is designed to reduce fever and inflammation. In many cases, this type of medication is also prescribed to aid with pain reduction. This treatment is often used to treat the symptom of inflammation, but further treatment for the underlying cause will still be required. Proper dosing is essential to reduce the risk of side effects associated with anti-inflammatory drugs. 

Drugs designed to thin the blood or for use in breaking up clots may be prescribed if thrombosis is the cause of vein inflammation. This treatment carries a moderate to high risk and is not appropriate for all patients. Hospitalization for observation will likely be required if this course of treatment is used. 

Surgical Intervention 

In some cases, surgery may be needed to remove a clot, repair vein damage, or remove tumors. As with any surgery, some risk is associated with this treatment. 

The prognosis for a cat experiencing phlebitis will depend on the cause of the inflammation. If the issue is a moderate condition like many infections or other treatable diseases, the prognosis is good. More serious conditions like blood clots or cancers may not respond as well to treatment. Some blood clots may be untreatable. If your pet is able to return home, be sure to follow all of your veterinarian’s instructions. Provide proper doses of medication, limit the cat’s mobility, and return for all requested follow-up visits. If symptoms return or worsen, seek veterinary assistance immediately.