If you insult them, they will not read your mail, they will not even consider what you have to say. It only convinces them that only low class people support the dogs. Even pro-dog people are alienated by the use of inflammatory language. Don't alienate your allies or potential allies.
People are outraged.
Something must be done. Help them find a way thru this. Don't just criticize, offer acceptable alternatives. Breed Specific Legislation. Not everything they propose is outrageous.