OMG I finally found it

[essentialsaltes]

Spook!
An important formative book from my childhood. But my memory is so bad I thought it was about a cat, but it was really about a dog, since the witch was allergic to cats.

Comments

[essentialsaltes.livejournal.com]

Already bought through ebay!

[colleency.livejournal.com]

I'm almost positive I read that book as a child, too!