A saddle thrombosis is a blood clot which sticks in the artery going to the
back legs. It's not an internal bleed and is unfortunately a symptom of
HCM (hypertrophic cardiomyopathy) or a congenital heart disorder . Cats can
get this from any age (my two were diagnosed at 12 weeks old) but is more
common in cats over four. It is often sadly fatal.
I am sorry to say but any brothers or sisters have a 50% chance of this
condition as it is inherited as a dominant gene. They should have ultrasound
scans if possible at a cardiologist to see if they too have HCM or other
heart defects. If they do, knowing early can mean treatment to slow the
disease and reduce the risk of clots. Plavix is a medicine to thin the blood and
can cause an internal bleed rarely, but there would have to be major
arterial damage for that to happen. Five of my cats take plavix.
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