Arterial Thromboembolic Disease (Feline)
| PrintFeline arterial thromboembolic disease is caused by the movement of a thrombus (clot), typically from the left side of the heart, through the vasculature as an embolus, until becoming lodged in smaller artery, preventing oxygenation of tissues downstream. The most common place for this to happen is the trifurcation, or triple split, of the aorta, the largest artery in the body, where it branches to supply the hind legs. More rarely, emboli can lodge in other vessels in the body including those in the brain, the gastrointestinal tract, the lungs, and the kidneys. Feline arterial thromboembolic disease less commonly occurs secondary to neoplasia (cancer) and hyperthyroidism, and rarely without any known underlying disease. Feline arterial thromboembolic disease is often the first warning for owners that their cat has cardiac disease. Affected cats suddenly cannot use one or more of their hind limbs and are acutely painful. The rear legs are usually cool to the touch and discolored blue from the lack of circulation. This painful, life-threatening situation carries a poor to grave prognosis on its own which is typically compounded by that of the underlying condition.
Common name: Saddle thrombus, Blood clot
Scientific name: Feline arterial thromboembolic disease, Systemic arterial thromboembolism, Cardiogenic embolism
Diagnosis
Signalment
Approximately two-thirds of feline arterial thromboembolic disease patients are male due to the higher incidence of a heart muscle disease called hypertrophic cardiomyopathy. Abyssinians may be uniquely predisposed above and beyond their predilection for heart disease. Feline arterial thromboembolic disease can occur at any age and is most common in middle aged cats.
Incidence/prevalence
The incidence of feline arterial thromboembolic disease in the general population has been estimated to be 0.6-0.7%. Among cats with hypertrophic cardiomyopathy, the incidence is reported to be 13-17% clinically and up to 41% on examination after death. Cats that survive one episode are at high risk for a second thromboembolic event.
Geographic distribution
There is no known geographic predilection for this disease.
Clinical signs (primary, most to least frequent, scientific term, synonyms)
No femoral pulses (in hind legs), Paresis (weakness) of one or both hind legs, Paralysis of one or both hind legs, Cyanotic (blue discoloration) of paws and cool temperature of the paws.
Clinical signs (secondary, most to least frequent, scientific term, synonyms)
Painful (secondary to muscle damage from poor blood flow), Tachypnea (breathing fast, secondary to pain), Hypothermia (low body temperature, secondary to shock), Hyperglycemia (elevated blood sugar, secondary to stress), Rigid muscles and elevations of muscle enzymes (secondary to damage from poor blood flow), Azotemia (elevations in kidney parameters, secondary to poor blood flow).
Cause (scientific, common term)
Cardiomyopathy (heart muscle disease) and other types of cardiac disease, Hyperthyroidism (overactive thyroid gland) Neoplasia (cancer).
Organ system affected (most to least affected)
Cardiovascular, Neuromuscular.
Diagnostic tests
Physical examination, Echocardiogram (ultrasound of heart), Chest radiographs (X-rays), Biochemistry panel.
Differential Diagnosis
Trauma, Urethral obstruction (males).
Overview
Feline arterial thromboembolic disease is caused by the movement of a thrombus (clot), typically from the left side of the heart, through the vasculature as an embolus, until becoming lodged in smaller artery, preventing oxygenation of tissues downstream. The most common place for this to happen is the triple split, of the aorta, the largest artery in the body, as it branches to supply the hind legs. More rarely, emboli can lodge in other vessels in the body including those in the brain, the gastrointestinal tract, the lungs, and the kidneys. Feline arterial thromboembolic disease less commonly occurs secondary to cancer and hyperthyroidism, and rarely without any known underlying disease. Cats with cardiac disease are predisposed to feline arterial thromboembolic disease, Affected cats are suddenly unable to use their hind legs and have poor or absent pulses with cold, blue-discolored paws and painful, rigid muscles. Approximately two-thirds of feline arterial thromboembolic disease patients are male due to the higher incidence of a heart muscle disease called hypertrophic cardiomyopathy. Abyssinians may be uniquely predisposed above and beyond their predilection for heart disease. Feline arterial thromboembolic disease can occur at any age and is most common in middle aged cats. Aside from signs associated with the underlying disease, which may or not be evident, there are no warning signs. In retrospective studies, the episode of feline arterial thromboembolic disease was the first indication of cardiac disease in 76.4-89% of patients, although evidence of congestive heart failure is not uncommon on examination. When an echocardiogram (ultrasound of the heart) is performed on these patients, most have an enlarged, although studies disagree as to whether the degree of enlargement predisposes to feline arterial thromboembolic disease. The presence of a clot and in the left atrium is a risk factor for feline arterial thromboembolic disease. The exact mechanism by which cats are predisposed to developing clots in the left atrium is not well-understood.
Treatment
Home Care
Feline arterial thromboembolic disease is a medical emergency. Immediate veterinary care is required.
Professional Care
Affected cats should be administered pain relievers. Anticoagulant medication can prevent the formation of additional clots and may include warfarin, unfractionated heparin, low-molecular weight heparin, and/or aspirin. New antiplatelet drugs like clopidogrel may also prove helpful. Fluid therapy to promote circulation is beneficial if the heart can tolerate the load. Promotion of vasodilation with application of heat to the affected limbs may help. Agents used to break up the existing clot (streptokinase; tissue plasminogen activator, TPA) are expensive and have not been shown to improve survival. Complications following return of blood flow and flushing of damaged tissue can be severe.
Action
Because feline arterial thromboembolic disease is most commonly secondary to underlying and previously undiagnosed cardiac disease, it is crucial to assess cardiac function and to discuss the management of the primary condition and the prognosis associated with it with your veterinarian.
Outcome
In several studies, the survival rate averaged 35%, including cats euthanized based on poor prognosis for full recovery, underlying cardiac disease or cancer, and/or potential for recurrence. Rectal body temperature is an important indicator of survival. A lower temperature, an indicator of shock, carries a worse prognosis. Cats with heart disease had significantly shortened survival time (77 days) versus those without (223 days). To date, no medication entirely prevents recurrence. Low dose aspirin therapy (5 mg/cat every 3 days) may prevent recurrence. Cats with a history of feline arterial thromboembolic disease require life-long care.
Recommended Treatment
Feline thromboembolic disease is life-threatening and requires immediate veterinary care.
References/Additional Readings
Hogan DF, Andrews DA, Green HW, Talbott KK, Ward MP, and Calloway BM. Antiplatelet effects and pharmacodynamics of clopidogrel in cats. J Am Vet Med Assoc 2004;225(9):1406-11.
Laste, Nancy J. and Harpster, Neil K. A Retrospective Study of 100 Cases of Feline Distal Aortic Thromboembolism: 1977-1993. JAAHA Nov/Dec 1995;31:492-500.
Schoeman, JP. Feline distal aortic thromboembolism: a review of 44 cases (1990-1998). J Fel Med Surg 1991;1:221-231.
Smith, CE, Rozanski, EA, Freeman, LM, Brown, DJ, Goodman, Jennifer S, and Rush, JE. Use of low molecular weight heparin in cats: 57 cases (1999-2003). JAVMA 2004;225(8):1237-41.
Smith, SA, Tobias, AH, Jacob, KA., Fine, DM, and Grumbles, Pamela L. Arterial Thromboembolism in Cats: Acute Crisis in 127 Cases (1992-2001) and Long-Term Management with Low-Dose Aspirin in 24 Cases. J Vet Intern Med 2003;17:73-83.
Author
Donna Mensching, DVM
Editor
Steven Hansen, DVM, MS, MBA
DABVT, DABT
Please note that PetVet should only be used as a guide and in no way should be substituted for licensed veterinary care.
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