Our dear old dog Kiri (no longer with us) had some sort of infection and her ear ballooned up. The vet operated and cut and drained it. Then she had to wear a plastic thing around her neck so she couldn't scratch the stitches out. I don't know if we ever found out why - she just started scratching and eventually it made the ear swell. The whole thing was upsetting and expensive, but it didn't kill her.
She lived to be 17!!
She was a mixture of bull terrier and NZ cattle dog (called a Huntaway over here) and she was beautiful and intelligent.
Robyn