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Saddle Thrombus MY CAT WAS FINE JUST YESTERDAY What is saddle thrombus? A condition that affects cats that can occur very suddenly without any prior signs or symptoms. It occurs when a blood clot (called a thrombus) forms or lodges at the point where the main artery leaving the heart (the aorta) divides into the arteries supplying blood to the hind legs (the iliac arteries) and the vessel supplying the tail. Tell me more The aorta is the widest artery in the body, and when it splits at this trifurcation, the iliac arteries are significantly smaller. The thrombus (clot) normally forms in the heart and travels down the aorta without causing problems. When it reaches the iliac arteries it gets stuck occluding the blood flow and this means the legs no longer have a blood supply. Vital supplies of blood and oxygen are abruptly halted, with no backup (collateral circulation). Why does this happen? Any heart disease that causes abnormal turbulence can cause a thrombus to form in the left atrium. The most common cause is Hypertrophic Cardiomyopathy (HCM) which is a condition where the heart muscle becomes thickened making it harder for the heart to pump. Cardiomyopathy literally means heart muscle disease. Other causes: Restrictive Cardiomyopathy (RCM), scarring of the heart prevents normal pumping action. Dilated Cardiomyopathy (DCM), the walls of the heart balloon out causing an enlarged, weak walled heart. Mitral Valve Disease, the mitral valve controls the flow of blood on the left side of the heart, if it wears out blood flows backwards back into the left atrium. Heart Based Tumors What will I see? Symptoms THIS IS A TRUE EMERGENCY Howling, crying or screaming. A thrombus is extremely painful. Hiding and not wanting to be touched or moved. Open mouth panting Inability to walk, dragging one or both hind legs. Cold legs and feet. Toes may be pale or blue. GET TO THE VET AS SOON AS POSSIBLE What will the vet do? The vet will be suspicious based on the history and clinical signs. Ultrasound of the iliac arteries may show the clot. In 76% of cats with saddle thrombus, this was the first sign of heart disease. Chest x-rays will look for heart failure – this shows up as fluid in or around the lungs. Blood testing will assess general health and ability to tolerate medications. Echocardiography to classify the heart disease. Begin treatment of the underlying heart disease when the patient is stable. Treatment Pain management! Intravenous heparin to attempt to dissolve the clot. Aspirin or Plavix ® Physical therapy Oxygen therapy as needed. Intravenous fluid therapy. Surgical intervention is associated with a poor survival rate. Treatment Part 2 – More Detail The patient’s clotting factors and platelet count should be done before initiating heparin therapy. Low molecular weight heparin (LMWH) is the drug of choice for treatment. Aspirin and Plavix © are also used because they have anti-platelet activity. Streptokinase and urokinase are used in people to improve arterial blood flow. Few studies have been done in cats. In one study all the cats died after receiving streptokinase. t-pa or tissue plasma activator is also used in human thrombolytic therapy. This drug is very expensive and also hasn’t been widely tested in cats. Supportive Care Nursing care involves managing the comfort of the affected limbs. The legs need to be kept warm. Physical therapy including passive range of motion. The care giver moves a joint through its entire range of motion without assistance from the patient. Bladder support. The patient may not be able to urinate on his own and may need to have his bladder expressed. Drug Therapies for Preventing Recurrence The anti-platelet drugs: ◦ Aspirin has been in use for more than 30 years in treatment of thromboembolism. It works indirectly and has only moderate anti-platelet activity. ◦ Plavix or clopidogrel affects platelets directly and is thought to prevent recurrence of arterial thromboembolism. The anti-coagulant drugs: ◦ Warfarin interferes with Vitamin K and disrupts the clotting cascade. Warfarin should be used in conjunction with heparin. Warfarin can be challenging even a minor injury could cause a life threatening hemorrhage. ◦ Low molecular weight heparin (LMWH) is used in clot prevention. The most common side effect is minor bleeding. What is the prognosis? Unfortunately the prognosis is very poor. Even if treated successfully the likelihood of another clot forming is high. Cats with a rectal temperature of 98.9F have a 50% or higher chance of survival. 25% of pet owners elect euthanasia without attempting treatment. Median survival time of cats in heart failure is 77 days. Cats not in heart failure 223 days. Home Care: What to Expect It may take 3 weeks or more for the cat to regain hind limb function. Full function may never return. Care is similar to that of a paralyzed pet. Urinary and fecal incontinence is not uncommon. He will also have limited ability to groom himself. Frequent baths are a must to prevent urine and fecal scald. Underpads manufactured as a human incontinence aid are incredibly helpful in maintaining a clean environment. Be aware of the potential for pressure sores from sitting in one position for long periods of time, and scrapes from dragging the hind limbs around. His bladder may or many not need to be expressed to allow him to urinate. Continued physical therapy at home will help keep the limbs flexible. Prevention There is no known way to predict which atrisk cat will develop a embolism. The best prevention is regular veterinary exams. If there are any signs of heart disease: ◦ Heart murmur ◦ Change in rhythm ◦ Change in breathing patterns They should be followed up on: ◦ Blood tests ◦ Echocardiogram (ultrasound of the heart) ◦ Referral to a cardiologist (heart specialist) References CVCA Cardiac Care for Pets (2013). Echocardiogram [Ultrasound Image]. Retrieved from http://www.cvcavets.com/felinearterial-thromboembolism.asp Drs. Foster & Smith Educational Staff (n.d.). Saddle Thrombi Diagram [Line Drawing]. Retrieved from http://www.drsfostersmith.com/images/articles/a_1463_Saddle_Thrombi.jpg The Merck Manual For Pet Health (2011). Thrombus [Line Drawing]. Retrieved from: http://www.merckmanuals.com/pethealth/cat_disorders_and_diseases/heart_and_blood_vessel_disorders_of_cats/blo od_clots_and_aneurysms_in_cats.html Nelson, R. W., & Couto, C. G. (2003). Aortic thromboembolism in a cat [Photograph]. Retrieved from http://www.answers.com/topic/aortic-3 Pavlina, S. (2013). Feline arterial thromboembolism: A terrible FATE. Veterinary Technician, E1-4. Retrieved from http://www.vetlearn.com/veterinary-technician/feline-arterial-thromboembolism-a-terrible-fate Ware, W.A. (n.d). Hypertrophic Cardiomyopathy [Drawing]. Retrieved from http://maxshouse.com/Illustrations/Hypertrophic_Cardiomyopathy-Dia.jpg