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What is Saddle Thrombus

A couple of weeks ago, I mentioned that Meow Meow suffered from a complication of heart disease called saddle thrombus or FATE. Further, due to her condition, we decided to put her to sleep. But what is saddle thrombus? What are the signs? Does it affect dogs too? And can it be prevented? Continue reading as I answer these questions and more.

Distal aortic trifurcation thromboembolism, aortic thromboembolism, and saddle thrombus are all similar. And you’ll usually see them used interchangeably as well. Moreover, aortic thromboembolism or ATE is a deadly illness. Plus, when a blood clot or thrombus gets established in the aortic trifurcation, it extends down into the external iliac arteries. At that point, it ends up resembling a saddle. Thus, the term saddle thrombus.

Causes of Saddle Thrombus

black pug
Photo by Charles on

You already know that saddle thrombus occurs in cats. In fact, it’s more common in male cats than females. And although it’s rare for dogs, it does happen. Additionally, just as with cats, saddle thrombus is more prevalent in male dogs than females. However, saddle thrombus is usually caused by heart disease in cats, typically HCM. Though, with dogs, a variety of conditions can produce saddle thrombus, including

  • sepsis
  • cancer
  • cardiomyopathy aka heart disease
  • damage to the lining of a blood vessel
  • enlarged left atrium
  • heartworm
  • hyperthyroidism
  • iron deficiency
  • blood clotting issues
  • weakly performing heart
  • protein losing nephropathy (PLN)
  • and splenectomy

And according to this study, PLN was the most commonly diagnosed issue recognized to induce a hypercoagulable state. Therefore, it’s presumed there might be a connection between an increased tendency to develop blood clots caused by PLN and saddle thrombus formation.

Signs of Saddle Thrombus

Traits like unexpected paralysis, pain, respiratory distress, and sudden death can take place in both cats and dogs with acute onset of saddle thrombus. Despite that, it’s still rare for dogs to experience acute onset. Rather, canines are more likely to manifest symptoms of chronic onset of saddle thrombus compared to cats.

Signs of Acute Onset Saddle Thrombus in Cats and Dogs

black and white dog next to a calico cat on a brown couch

Since blood supply to hindquarters is blocked, both cats and dogs can experience

  • paralysis in one or both hind legs (cats)
  • back legs will be cold to touch
  • foot pads and nail beds may appear pale
  • cats will cry out or meow more
  • hypothermia
  • vomiting
  • possible respiratory distress
  • and sudden death
  • paralysis in one or both hind legs (dogs)
  • back legs will be cold to touch
  • foot pads and nail beds may appear pale
  • dogs bark and appear anxious
  • hypothermia
  • vomiting
  • possible respiratory distress
  • and sudden death

Symptoms of Chronic Onset Saddle Thrombus in Dogs

Chronic symptoms are more subtle and may only appear as weakness or limping. However, over time your dog may also present with

  • anxiety
  • coughing
  • trouble getting up or jumping
  • reduced ability to exercise or stamina
  • hypothryroidism
  • a limp due to weakness in back legs
  • lowered body temperature
  • toe wounds
  • sudden paralysis and pain
  • respiratory distress
  • weakness
  • and sudden death

How Saddle Thrombus is Diagnosed

man and woman looking at an ultrasound machine while Pomeranian is on a table
Photo by Tima Miroshnichenko on

Including the above signs, upon examination, femoral pulses on the inner upper back legs are typically absent on cats. And sometimes they’ll be absent on dogs. Therefore, a diagnosis of saddle thrombus can be made largely on symptoms alone. Given the gravity of the situation, most pet parents opt to euthanize their pets.

Otherwise, if treatment is still desired, more tests and diagnostics are required, such as

  • Xray
  • Ultrasound
  • Urinalysis (dogs)
  • ECG
  • and blood tests

Several factors should be considered when determining to pursue treatment rather than euthanasia. Issues that negatively impact survival with cats include

  • decreased heart rate
  • absence of motor function
  • having more than one leg affected
  • hypothermia
  • and a confirmed diagnosis of congestive heart failure (CHF)

And the main factor affecting survival with dogs is ambulatory status. For instance, dogs with aortic thromboembolism usually fare better if they are still walking compared to dogs who are paralyzed due to the same condition.

How to Treat Cats with Saddle Thrombus

tortoiseshell cat being treated at a veterinarian's office

Often cats need to be hospitalized for a week or two with saddle thrombus until stable. Additionally, they may be referred to a kitty cardiologist But, initially, treatment may consist of

  • pain medications
  • oxygen, if and when necessary, for CHF or respiratory distress
  • IV fluids for dehydrated cats
  • antithrombotic therapy, ie heparin
  • as soon as oral medicines are tolerated, then Plavix is started
  • next, when patient is stabilized and pain is under control, physical therapy of affected limbs is started

However, loss of blood flow to the hind leg can lead to tissue death. So, if only one leg is affected, amputation is an option. Though, there are some contingent aspects.

  • after patient is stable and comfortable, any necessary diagnostics for treating the underlying cause of saddle thrombus are carried out
  • and monitoring patient closely

How to Treat Dogs with Saddle Thrombus

veterinarian giving tan pit bull terrier injection of some medicine
Photo by Pranidchakan Boonrom on

As you’ll notice, much of the therapy offered to cats with saddle thrombus is similar for dogs as well. Nevertheless, there are a couple of differences, as you’ll see. In addition, treatment is not universal, which means it depends upon the veterinarian and their expertise. Therefore, if your dog has saddle thrombus, medical care might include

  • hospitalization, depending upon the severity of the patient’s condition
  • pain medications
  • oxygen therapy, if necessary
  • antithrombotic medication, such as heparin
  • aspirin and/or Plavix will also be started
  • although, if clotting isn’t broken up, then the patient may be referred to a specialist, or the veterinarian may opt to surgically remove the clot
  • and finally, treat the underlying cause of saddle thrombus

Outcomes with Cats and Dogs with Saddle Thrombus

black and grey cat with short hair on a white surface
Photo by Burak The Weekender on

Once cats and dogs have a saddle thrombus, the prognosis is very poor. Despite the effort, they’ll either end up not making it, or more than likely have another episode. Thus, most pet parents choose euthanasia for their pets as the most humane option of relieving their suffering. However, you will undoubtedly find instances online of pets who were discharged from the hospital or survived ATE. Though, from everything I’ve read, those examples are considered outliers.

For instance, this study, involving 250 cats that had FATE, revealed that over 150 of the cats were initially euthanized. The study followed the therapy, hospitalizations, deaths, and etc over a period of several months. Then, depending upon certain conditions, some of the cats survived up to a week. But, due to severity and other factors I’ve listed, many still didn’t make it. And others had 2 or even 3 additional occurrences of FATE. In the end, only 6 of the 250 cats survived.

And this one, regarding dogs with saddle thrombus, is similar, yet not as grim. It included 100 dogs at the beginning. But again, because of different issues, only 16 of the original 100 were still living half a year later.

Preventing Saddle Thrombus

a veterinarian checking a sick dog using a stethoscope
Photo by Tima Miroshnichenko on

Plavix is the recommended preventative treatment for saddle thrombus in at-risk cats. Though, many pet parents don’t know that anything is wrong with their cats until it’s too late. But that’s why vaccinations are a great time to see the vet. Moreover, if your pet has chronic issues, such as heart disease, CHF, or kidney disease, keeping up with visits is a necessity.

Although, there are things you can look out for as well, to be proactive. Since I know you care about your pets as much as I care about my own, I like to share the things I’ve hopefully learned. With Meow Meow dying, I look back on things I feel I should’ve noticed; things that make me question whether she was sick almost 2 years ago. But then I tell myself, Of course she was, silly! She had heart disease. Indications your cat might have an issue with their heart or be at-risk for saddle thrombus would be

  • water intake (drinking more than ~1 cup a day for an adult cat)
  • activity level has dropped significantly
  • appetite has changed as well or doesn’t eat as much.
  • losing weight
  • using the bathroom in places other than the litter box
  • panting or shallow breathing
  • stopped grooming themselves, ie. claws need trimming and they have dandruff
  • and/or periodic lameness in different limbs

Since I don’t know much about dogs with saddle thrombus, there wasn’t anything different online than what’s already listed. Yet, I feel like they would also present in some ways similar to a cat such as

  • activity level has changed, ie not doing as much or can’t do as much
  • appetite has changed, ie, doesn’t eat as much or eats more than before for an adult dog
  • weight gain or weight loss
  • panting or shallow breathing when not doing much exercise
  • periodic lameness in different limbs
  • low urine output compared to water intake
  • weakness
  • vomiting
  • and/or abnormal behavior

I based these symptoms on the conditions listed above that can cause saddle thrombus in dogs. Furthermore, if you’re concerned about your pet’s health, contact your veterinarian. The best prevention is early detection and treatment.

So, What is Saddle Thrombus

tortoiseshell shorthair cat asleep on a blue jacket next to window

Saddle thrombus can affect both cats and dogs. Although, it’s not as common with dogs as it is with cats. And while heart disease is the main culprit behind ATE in cats, there can be any of a number of issues in dogs. Moreover, dogs generally manifest chronic onset symptoms, whereas cats will have acute symptoms. Also, both cats and dogs are diagnosed and treated pretty similarly. However, veterinarians no longer surgically remove blood clots in cats.

In addition, both kinds of pets have a poor prognosis, depending on motor function. Furthermore, if cats have hypothermia, more than one limb affected, and CHF, that affects the outlook as well. But keep your pets’ annual visits with the veterinarian, so they can detect any changes. And if you notice anything out of the ordinary, please call the vet. I hope you never have to experience anything like that with your fur babies.

Thank you for taking the time to read this post. Please comment, share, and please don’t forget to follow.

Extras non fowl

HCM Heart Disease in Cats

HCM heart disease in cats is a condition that causes the heart muscles to thicken. Further, it can affect kittens and adults alike, as well as any breed and gender. In addition, it’s estimated that anywhere from 15% to 30% of cats have HCM. However, most cats with HCM show no signs of disease. On top of that, we had to put Meow Meow to sleep recently due to complications related to HCM. As a result, it’s my sincere hope to prevent other pet parents from losing their cats in like manner.

Typical for me, when we or our pets go through an illness or injury, I scour the web for as much information as I possibly can to understand, and to hopefully prevent or find a solution to the issue. What started as a limp in Meow Meow rapidly progressed to lameness in only a matter of a couple of days. At prior vet visits, we were never told she had heart disease; never heard the words heart murmur, mitral valve dysplasia, or arrhythmia.

What caused Meow Meow’s lameness was feline aortic thromboembolism, otherwise known as FATE or saddle thrombus. And once cats are diagnosed with FATE, such as Meow Meow was, there is rarely good news. Therefore, even though saddle thrombus essentially brought about Meow Meow’s death, HCM heart disease was at the root of it.

What Causes HCM Heart Disease in Cats

bengal cat lying on the floor
Photo by u7426 u5218 on

Genetic predisposition of HCM is the prevailing cause in many cat breeds, including Ragdoll, Sphinx, and Maine Coon. But HCM is also readily recognized in other purebred cats, including Bengal, Shorthair, Norwegian Forest, and Persian. So heredity is thought to be a determining factor with those breeds as well.

Although, other cat breeds, including mixed breeds, are speculated to have similar genetic causes to their HCM, work directed toward finding those remains unfruitful as of yet. Plus, mixed breed cats generally either don’t have well-documented family history or no family history of HCM. Thus, scientists believe there are also other, unknown causes of HCM.

Though, according to Cornell Feline Health Center, both hypertension and hyperthyroidism lead to HCM. Lastly, chronic kidney disease (CKD) and heart disease are often linked together in humans and cats; either one can provoke the other.

Symptoms of HCM in Cats

close up photo of dark gray British shorthair cat
Photo by Marianna OLE on

First of all, since cat owners don’t regularly exercise cats, unlike their dog counterparts, there might seem to be no symptoms of HCM heart disease in cats. Often dubbed the silent killer, because pet parents aren’t aware their fur baby has it until heart failure, FATE, or even sudden death.

But that doesn’t mean changes aren’t occurring. Even as the heart becomes less effective, your cat’s body makes up for the disease, concealing symptoms.  Think of small adjustments their body makes over time, ones we don’t register. Sadly, extended activation of such compensatory mechanisms damages the heart muscle and other organs in the end stages of the disease. Therefore, for clarity, I’ll divide the symptoms into 2 distinct medical conditions.

Congestive Heart Failure (CHF)

orange tabby cat wrapped in gray and white blanket
Photo by Tatiana u0410zatskaya on

CHF occurs if your cat’s heart isn’t pumping enough blood to other parts of their body, causing fluid to back up in the lungs.  Humans with CHF often compare it to drowning. And according to BMC Veterinary Research, cats affected with HCM have been shown to carry a 23.8% risk of developing congestive heart failure. Furthermore, symptoms of CHF in cats include:

  • Heart murmur
  • Abnormal heart rate or rhythm
  • Increased time spent sleeping while less time being active or playing
  • Weight loss, including decreased appetite and vomiting
  • Elevated breathing rate and/or effort
  • Pale or blue gums and cold extremities
  • Fainting or loss of consciousness
  • Open-mouth breathing or panting
  • Ungroomed appearance–upon close inspection, they might have dandruff in their fur, and/or long claws
  • And sudden death


black and white digital drawing of a cat showing thromboembolism, with heart, aorta and saddle
Digital Art, Courtesy of Sarah Smith

A thromboembolism is a blood clot that breaks off and causes a blockage.  And based on Purdue College of Veterinary Medicine, as of 2003, thromboembolism was observed in around 50% of cats with HCM. In addition, where the clot breaks off and settles determines the symptoms.

  • Stroke – a blood clot that blocks blood flow in the brain.  And signs consist of seizures, weakness, blindness, falling, muscle spasms, and coma.
  • Pulmonary embolism – a blockage that occurs in the lungs. And the signs are labored and rapid breathing. But the cat can also cough, have blue-tinged gums, faint, and/or go into shock. In addition, sudden death is also possible.
  • Aortic thromboembolism, aka saddle thrombus. 89% of cats with saddle thrombus have some form of heart disease. However, HCM is the one most often to blame. And saddle thrombus appears because a blood clot travels from the aorta and settles in the saddle, cutting off ALL circulation to one or both back legs. Additionally, it generates extreme pain and paralysis, and is often fatal.

Furthermore, in some cats, the strain of FATE deteriorates their cardiomyopathy leading to acute congestive heart failure.  So you see, a cat can have both saddle thrombus and CHF with cardiomyopathy. Though, it’s not common. And if it happens at all, it’s usually later in the disease.

How HCM Heart Disease in Cats is Diagnosed

2 vials of blood samples
Photo by Karolina Grabowska on

Unfortunately a DNA test is not how heart disease in cats is definitively diagnosed. Seeing that some cats that are predisposed to it don’t fall ill with HCM, even as other cats aren’t do. However, your pet’s veterinarian might hear a heart murmur at a routine office visit. Or another symptom might pop up, in which case the vet may recommend

  • proBNP blood test that measures the NT-proBNP hormone that’s released by stretched or stressed muscle cells in the heart. Despite being reported to have a 90% accuracy rate, there are other issues that can influence the test results.
  • echocardiogram is considered the gold standard when assessing the heart. This feline echo shows an image of the heart so veterinarians can then evaluate the heart size, shape, and the way it functions. Moreover, the veterinarian will be able to measure wall thickness, examine heart valves, and check blood flow. Echocardiograms can also be used to detect some heartworm infections.

Depending on your pet’s symptoms, your veterinarian may recommend a chest X-ray and/or an electrocardiogram (ECG) besides. The X-ray would look for fluid on the lungs. And the ECG would reveal any heart rhythm abnormalities.

Just be aware that if your cat doesn’t have HCM heart disease now doesn’t mean they won’t at some later time. Thus, if you have a high-risk breed, like one listed above, you should get them regularly tested.

Treatment for HCM in Cats

4 different pill bottles and 3 packets of medications next to blood pressure cough on wooden boards
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Fortunately, many medications formulated for people are also prescribed for cats with similar issues, as you’ll see below. However, don’t give any medicines to your pets until clearing it with your veterinarian first. Obviously dosages are completely different. In addition, disease progression will dictate treatment. But overall, the veterinarian may want to

  • slow your cat’s heart rate, correct arrhythmias, and lower blood pressure

Beta blockers like atenolol can slow heart rate and lower blood pressure. And calcium-channel blockers, such as Cardizem, are used for cardiac arrhythmias.

  • minimize clot formation

Plavix is usually better than aspirin at preventing further clots, according to Morris Animal Foundation. .

  • alleviate fluid build-up with CHF and change your cat’s diet

Diuretics like furosemide are used to drain excess fluid from the heart and/or lungs. Plus, oxygen therapy and needle aspiration are additional options if congestive heart failure is severe.

Also, your cat’s veterinarian likely won’t recommend changing any diet UNLESS your fur baby has congestive heart failure. That’s because unrestricted sodium intake for cats with CHF causes fluid retention. Talk to your veterinarian, or look here for ideas on what to feed your cat if they have CHF.

  • and lastly, give your cat pain medicine if needed

Prognosis of HCM Heart Disease in Cats

orange tabby cat lying on a green surface
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There are many variables involved when evaluating the prognosis for HCM in cats, like your cat’s age and how advanced the heart disease is. In addition, how well your cat responds to treatment affects the outlook as well. However, generally HCM heart disease is a progressive disease. Usually once symptoms appear, unless the first one is a blood clot, cats live about ~ 2 years. Otherwise, the odds are less than that.

Moreover, it’s vital to understand that heart medications don’t cure HCM. Although, they can prevent the disease from getting worse, and/or from causing secondary issues. Nevertheless, the best plan is to get cats diagnosed early, before any symptoms start.

HCM Heart Disease in Cats

close up of tortoiseshell cat sitting on a couch
Meow Meow Kitty Kitty

As I’ve learned about hypertrophic cardiomyopathy, and all of the resulting symptoms and complications, I realized why we didn’t notice the subtle signs in Meow Meow. She was a middle-aged cat when she came to live with us. Perhaps if she was kitten or a year old back then, things might have been different. But when Meow Meow came to us, she was already deep in her habits of sleeping all day. Therefore, we had nothing with which to compare her behavior.

Again, HCM is a degenerative disease, especially once symptoms start showing up. But it doesn’t have to be a death sentence. Even something as simple as excessive sleeping or an unkempt appearance should be taken as a sign that something is off. Because the sooner treatment can be started, the better your cat’s fighting chances are.

Thank you for taking the time to read this post. I hope you enjoyed it. Please post a comment, share, and don’t forget to follow.