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Saddle Thrombus In Cats

The largest artery in the body that is the main “highway” for the propagation of oxygenated blood from thr heart to the tissues is the aorta. The feline aorta leaves the heart with oxygen rich blood and courses through the chest and ultimately through the abdomen heading toward the tail. At the level of the pelvis, the aorta splits into two smaller arteries that ultimately supply blood to the tissues of each leg. It is at this split where formed clots can get lodged, leading to a severe medical emergency called a saddle thrombus.

Saddle thrombus is exclusively a feline phenomena, causing a severe situation where the lodged clot cuts off blood supply to the legs. The lack of nutrient rich, oxygen rich blood reaching the tissues of the legs leads to severe pain, disuse of the legs and severe damage to the tissues, blood vessels, and nerves.

Typically, cats that are predisposed to saddle thrombus have underlying cardiac disease that increases turbulence to the flow of blood through the heart. This increased turbulence makes these patients more prone to the formation of clots. Cats with hyper-thyroidism are prone to a cardiac condition called hypertrophic cardiomyopathy. Therefore, saddle thrombus tends to be associated with cats that have hyperthyroidism.

Cats that have formed a saddle thrombus typically appear paralyzed, unable to move the rear legs. They are often vocalizing due to severe pain. When touched, the back legs are often cold and stiff, and sometimes there is panting and trouble breathing.

Due to the time sensitive nature of the irreversible consequences of saddle thrombus, as well as the severe pain that saddle thrombus causes, it is strongly recommended that one seek immediate veterinary care for one’s cat if saddle thrombus is suspected.

Saddle thrombus is diagnosed by a combination of history, presentation, cold/stiff rear legs, and lack of any palpable pulses in the rear legs. Chest x-rays will often indicate evidence of cardiac disease, and even congestive heart failure.

Prognosis is poor for saddle thrombus, even when found early. Treatment is geared toward managing pain and re-establishing blood supply to the legs through the use of IV clot busters such as heparin, or surgical removal of the clot. In many cases, however, the damage to the tissues, blood vessels, and nerves of the rear limbs is too severe and irreversible for treatment to offer a return quality of life, leaving euthanasia the most humane option for the patient.


Roger L. Welton, DVM
Founder and Chief Editor,
President, Maybeck Animal Hospital

CEO, Dr Roger’s Holistic Veterinary Care

Article updated 6/3/2014

7 thoughts on “Saddle Thrombus In Cats

  1. Lillie Taylor says:

    This week I had to make the horrible decision on what to do for one of my kitties. After being told that his heart was enlarged (not sure if that was from the beginning of his life or something that happened recently…I’m not a medical professional so I don’t know how that happens) and had a small amount fluid on his lungs along with the diagnosis of saddle thrombus we chose to humanely let him go. I could not imagine letting him live in pain since pets can not vocalize to us when something is wrong or risking him having another clot or some worse heart condition while we were at work and leaving him to suffer alone for hours. We were fortunate to be home when it happened this time and got him to the vet immediately. Sorry for the long story to get to the point of my post, but he is one from a litter that we fostered from kittens and decided to keep 3 of them. His sister passed away 3 years ago from some kind of unknown neurological issue. At least this is the only answer our vet could find. We now have only 1 of this litter left and he is 12 years old. It makes me very apprehensive that there is something in all the kittens from that litter (paranoid fur-mommy). Would a pre-emptive x-ray tell us anything that would help if the remaining kitty has a similar heart issue? Is there a medication he could take that might prevent a clot or is that even too dangerous to give them?

  2. Laurie says:

    This evening, I lost my beloved Odysseus to saddle thrombus. We made the decision to end his pain and it was so very hard to let him go. He was my very special cat friend and I will miss him dearly. He was 10 years old. This article is a spot on description of the symptoms and helps me to understand what happened to my little love. It also reassured me that we made the right decision. Thank you

  3. Cherie says:

    Saddle Thrombus is not necessarily only for cats. Ferrets will also be afflicted by this. It’s just as horrific for them. I just had one go through this two nights ago.

  4. Hannah mae says:

    I lost my dear tabby cat Joey to this this morning. At first I thought he had been hit by a car until I sadly found out the severity of it at the vets. I made the decision to put him down he was only 3 years old and I shall miss him dearly.this gives me understanding of what has happened and has been such an awful shock for us. Didn’t expect to loose him this soon it’s such a sad thing to happen and so rapidly. He seemed fine last night and then by morning couldn’t my little man ,x

  5. Lee says:

    Lost my lovely cat max on Sunday to saddle thrombus . I’d taken him to vets both previous days ( he was also on thyroid medication) because he’d been sick and breathing wasn’t quite right. He was given antisickness injection and steroid . He woke up Sunday I thought he was looking and feeling better when he was suddenly sick then howling and could not walk .Had to wait for an hour for vet to get to surgery . It was terrible . Nothing could be done so he was put to sleep . I can’t get over the shock miss him terribly . R I p max love you x

  6. Janice says:

    Just lost my little Belle (13) to saddle thrombus. Her brother, jasper(11), had it two years earlier. In both case I was woken up in the wee hours of the night by a screaming cat. The male was completely paralyzed in the hind end and Belle partially. Both had to be euthanized.

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