I'm currently fostering a breeder surrender girl that has cauliflower ear. From what I've read, it's caused by possibly ear mite infections left untreated. The injury is from them scratching and shaking their heads back and forth. The bumps are hematomas and left untreated form into the cauliflower looking masses.
Unfortunately for this little girl it probably will require surgery. Her ear canal is almost totally blocked from the mass.
What is a Cauliflower Ear?
Any animal with ears can get a cauliflower ear. They are common among cats and dogs, especially those with ear mites. Ear mites cause an animal to bite or scratch at its ear, and also to shake its head repeatedly. This trauma can result in a hematoma. Just like with humans, a hematoma in a pet should be treated to prevent infection and disfigured ears.