Can anybody tell me what caused this?

[Miss Z]

Were any x-rays taken by either vet? Was there swelling, is that why the first vet first thought it was an abscess and then an inflamed joint? If he thought it was an inflamed joint, why put your cat on antibiotics rather than an anti-inflammatory?

This is indeed very strange, even with my vestigial knowledge of vet. pharmacology! If the amoxicillin clearly wasn't improving the situation, there was either one heck of an infection or NO infection to begin with. I can't think of a logical reason to re-prescribe the same drug and dose if symptoms were worsening rather than improving.

The heat around the swelling speaks immune reaction to me. I first thought it could be something to do with leakage of joint fluid provoking the inflammation. In my readings, I've heard of autoimmune-type diseases happening similarly in humans, and to some extent dogs, but never to the point that the animal gets as bad as I.R.Kitty. It does seem like a bit of a mystery.

The FIV thing I really don't understand. As far as doing a 'quick' blood test, there's quite a few options; I'm assuming in this case the vet must have carried out something along the lines of an ELISA SNAP test. However, since you say there was no fever, and that she otherwise seemed well, I am really unsure as to how he validated his test result (as mrspunkysmom said, the tests are not gospel, and a diagnosis is a combination of observed clinical signs and test data). Unless he thought it was well into its 'silent' period by then, although I'm sure there would be obvious loss of condition by that time.

If I ever come across anything in my next four years of study, I'll give you a shout!

[whoopdeedo]

Hello again, I wanted to add this update. I went through my filing cabinet and found the receipts of I.R.'s vet visits from last year. Here is a list of the dates and the treatment:

First visit to first vet: June 8, 2011. Treatment: Amoxidrops 30ml, Penicillin Procaine G per cc.

Second visit to first vet: June 13, 2011. Treatment: Dexamethasone per ml.

First visit to second vet: July 7, 2011. Treatment: Amoxidrops 20ml.

Third visit to first vet: July 16, 2011. Treatment: Clavamox drops 15ml.

I.R's still doing great, but she's got a new thing that she does that I suppose is a result of this happening to her. She only started doing this a couple of weeks ago. On her left side whenever we try to comb her or pet her near her back leg she has a spasm. She stretches out and gets stiff as a board and meows, but not like she's in pain, it sounds more as if she's confused. It stops after a few seconds and then she's back to normal. To avoid this from happening I try not to touch that spot, but sometimes it's unavoidable. Other than this new development she's still the same.

Thanks everyone for your help.