I recently wrote about twisted stomach in the dog which is a fairly common out of hours acute emergency, while this condition does not occur in the cat there are other emergency situations which of course do happen, one of which is aortic thromboembolism, also known as a saddle thrombus. Again I saw many of these while I was in practice and the outlook was always pretty bad, more so than the twisted stomach in the dog. What happens is that a clot forms and blocks the lower part of the circulation causing loss of function of the hind legs. Typically the owner will arrive thinking their pet has been hit by a car and they will be very concerned as it will be obvious their cat is in great pain.
Cause : This condition probably is the result of an existing heart condition such as cardiomyopathy, because of this it usually affects older and middle aged cats. Some vets think it can also be as a result of hyperthyroidism but this is most likely rare. Logically anything which will produce a blood clot can lead to aortic thromboembolism.
Clinical Signs : These cases will be presented as acute emergencies, the affected cat will have experienced sudden loss of use of its hind legs, when you feel the hind legs they will be colder than the front legs and the rest of the body due to the lack of circulation. These cats are normally crying as they are in distress and pain, the vet will confirm a loss of femoral pulse and he may also be able to detect the underlying heart disease.
Treatment : My success rate with this condition was very low and most affected cats died or euthanasia was carried out. Surgery has been carried out by some vets to try and remove the clot and re-establish the circulation, this is rarely done and I understand the results have been variable to say the least. A number of drugs have been used which have had occasional success, these would include acetylpromazime as a vasodilator, and anticoagulants such as warfarin, heparin and aspirin. Streptokinase would be a logical drug to try but it is delivered via an aortic canula and as such may be beyond the skills of some vets in general practice such as myself.
Prevention : The most logical prevention would be to keep your cat fit, thin and well as so less likely to be affected by heart disease. If your cat is lucky enough to recover from this condition then drugs like aspirin would make a repeat episode less likely. Aspirin doses should only be calculated by a vet as this drug can be very toxic to the cat.
So that was a concise brief description of aortic thromboembolism, like twisted stomach in the dog it is a young vet’s nightmare scenario, you know what is going on, you know the right thing to do as far as treatment goes but you also know that in this case your efforts will probably end in euthanasia or death of your patient. I guess that’s life, and as clinicians we have to distance ourselves from any emotion and do our best.
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You may be interested to know that my cat has survived 2 blood clots. He has heart disease which was identified at the time of him having his first clot. He takes frusemide, clopidogrel, fortekor and asprin every 72 hours. He has been scanned and his left ventricle doesn’t vary much in size to his right which is apparently unusual. He is only 4 years old and leads a relatively normal cat life. Unfortunately I am always on tender hooks waiting for the next clot as I am aware that they tend to re-appear after 6 months and his first clot was 5 months ago.
Thought this may be of interest
Forgot to say that he never has any symptoms whatsoever. His back legs go from underneath him and that is it