House ate my pet

[plague08]

I had a Shrunken Pet (mule) that that i sat on the floor of my house. As soon as i sat it down it disappered.

It was the second story and i look below and in any creates in the house no luck.
Anyone have any ideal how i can recover it. This is the second time something like this has happened in two houses.
I used transparency and looked around aswell.

[plague08]

I found it! It was under the floor boards of the house. (Bug?)
Has this never happened to anyone els?