My cat was diagnosed with heart disease and lately will randomly act like he can't walk good. The first time it seemed like his leg gave out and he just crouched down for 3 or 4 minutes. Then he got up and was totally normal. No issues at all. It happened again tonight but I didn't see his leg give out he just started doing this weird crouch walking thing. Again, in about 3 or 4 minutes he was totally fine. We have taken him to the vet and they did an ultrasound and do not see any signs of blood clots. Is there something else that could be causing this? They did give him a very low dose of blood thinners just in case but honestly it's a nightmare giving it to him and half the time it doesn't work. He spits it out or severely foams at the mouth we can't figure out the best way to get him to swallow, it he just freaks out