Saddle Thrombus in Cats: Causes, Symptoms, and How To Help Your Cat

What Is Saddle Thrombus in Cats?

Imagine your cat’s vascular system as resembling a tree.

The aorta, like a tree trunk, is the large vessel that runs from the heart down a cat’s body. It branches off into many arteries, like the branches of a tree.

Sometimes, a blood clot can become lodged where the aorta branches near the cat’s hind legs. This type of blood clot is called a saddle thrombus.

Another name for this condition is feline aortic thromboembolism (FATE).

If a blood clot blocks circulation to the hind legs in this region, the cat loses the ability to use them effectively, and their foot pads may take on a blue tint and feel cooler. This condition is very painful, and affected cats will often cry out when the clot occurs.

Saddle thrombus is a medical emergency and requires immediate veterinary attention.

Symptoms of Saddle Thrombus in Cats

Saddle thrombus in cats has several distinct symptoms, including:

• Sudden hind leg paralysis

• Vocalizing and signs of pain

• Rapid breathing

• Panting

• Bluish-tinted foot pads

• Back legs feeling cool to the touch

• Weak pulses in the back legs

Causes of Saddle Thrombus in Cats

Most cats who experience saddle thrombus have underlying heart disease.

Heart disease disrupts the normally smooth flow of blood. When blood flow becomes choppy or turbulent, it is more prone to develop clots.

These clots can lodge in the aorta specifically where it branches and supplies their legs with blood in the saddle region.

Even though about nine out of 10 cats who have a saddle thrombus have heart disease, most of them never show any previous signs of heart trouble.

Unfortunately, for most patients, the saddle thrombus is the first sign that something is wrong.

Aside from heart disease, a saddle thrombus can also be caused by cancer, most commonly lung cancer, or it can even occur spontaneously with no known cause.

How Veterinarians Diagnose Saddle Thrombus in Cats

A saddle thrombus in cats is usually diagnosed based on a physical exam by your veterinarian.

Your vet will likely take X-rays to assess your cat’s heart and lungs and rule out other causes of sudden hind leg paralysis and pain.

They may recommend additional testing, such as an echocardiogram (ultrasound of the heart), blood work, and possibly clotting tests.

Treatment of Saddle Thrombus in Cats

Unfortunately, this condition is very painful and has a poor prognosis.

Treatment usually involves prolonged hospital stays for supportive care and management, followed by a long recovery period with extensive nursing care required at home.

Treatment involves pain medications, blood thinners, and physical therapy while waiting for the clot to break down and dissolve.

During this period, affected cats may need help with going to the bathroom. They are often stressed from pain and fear from not being able to use their back legs. As a result, many will not eat their food.

These cats may require appetite stimulants or assisted feedings to avoid developing other problems.

Affected cats are often initially anxious and feeling pain, with concurrent underlying heart disease that must also be managed. For pet parents seeking treatment, referral to a 24-hour care facility may be recommended as round-the-clock oxygen therapy is sometimes needed.

If heart failure is present, it must also be treated with diuretics, like furosemide, and an ACE-inhibitor medication, like benazepril.

Your cat’s cardiologist may recommend other heart medications as well, depending on what they see on your cat’s echocardiogram.

Humane euthanasia is elected by more than half of pet parents of cats affected by saddle thrombus.

Of those who decide to try treatment, about half of treated cats survive to be discharged from the hospital.

Recovery and Management of Saddle Thrombus in Cats

Cats who respond to treatment often start to get use of their back legs returning slowly around four days to a week or so after the clot is diagnosed.

Even once they start to be able to use the legs again, full return to function takes weeks.

Unfortunately, regaining use of the legs is only half the battle, as they are much more likely to have another clot in the future and require lifelong blood thinners to reduce this risk.

Many affected cats will form more blood clots that can travel to other more dangerous places, like the lungs.

After your cat is discharged from the hospital, they will likely need physical therapy and several modifications to their environment to support them during their recovery.

Because your cat likely won’t have full use of their back legs yet when they are discharged from the hospital, you will want to make sure they have easy access to all their resources.

Keep your cat confined in a small, safe space where they are not able to fall and hurt themselves.

Getting in and out of the litter box can be a struggle, so some affected kitties may struggle with cleanliness as they accidentally soil themselves while trying to go to the bathroom.

Hygiene is important to avoid secondary skin infections, so be sure to keep them clean and bathed as frequently as needed.

Pee pads can be useful, as they are easy to dispose of and change when soiled.

If cat diapers are used, be sure that they are cleaned regularly and that your cat is not sitting in a soiled diaper.

Talk to your veterinarian about physical therapy at home to help restore normal movement in the legs and avoid muscle atrophy.

Many affected cats benefit from passive range-of-motion exercises where their hind legs are flexed, extended, and rotated as if they are pedaling a bicycle. You can try these exercises gently for five to 10 minutes, depending on their tolerance, several times a day.

Prevention of Saddle Thrombus in Cats

As most saddle thrombus events are caused by underlying heart disease, prevention of heart disease is key to preventing blood clots.

Avoid breeding cats diagnosed with heart diseases such as hypertrophic cardiomyopathy (HCM).

Keep your cat up to date on annual wellness visits with their vet for early screening and detection of any underlying disease.

While there is very little you can do to prevent the initial saddle thrombus, the risk of recurrent clots is significantly reduced with blood thinners.

Your cat’s vet and veterinary cardiologist can help make a long-term medication plan to prevent future clots.