Mechanics have weeks where they see a slew of brake jobs, or more carburetor issues than usual. There's no rhyme or reason; it's an odd universal phenomenon. Dog trainers, too, have weeks where they seem to hear about an awful lot of the same type of issues. This week, for me, it's been life-threatening, severe aggression issues.
When I say "life-threatening," I don't mean the dog is mauling people; I mean solutions are being discussed that include ending the dog's life. These can be the toughest types of issues that trainers deal with, both behaviorally and emotionally, but that emotional pain is multiplied exponentially for the owners.
No one gets a dog expecting it to behave aggressively. By the time a bite or multiple bites happen, the family is normally very attached to the dog. I have worked with a multitude of aggressive dogs over the years. Some had mild issues such as fear-based reactivity toward other dogs, or snapping at people. Some issues were more moderate, and the dog had already bitten someone. And there have been those who had puncture-wounded multiple people.
For severe cases, before anything else, I recommend a veterinary exam that includes a full blood workup (including a full thyroid panel conforming to Jean Dodd's specifications) and a thorough physical exam to rule out any type of physiological cause for the aggression. Assuming the dog is physically sound, for those dogs at the extreme end of the aggression spectrum, options are limited:
Training: Owners must be wholeheartedly committed to a behavior-modification protocol. They must use careful management in the meantime so that no one is hurt. Even with owners who are completely committed, though, if there are children in the home, training might not be a viable option, as the children's safety must come first.
Management: I have known people who have had severely aggressive dogs but managed the dogs so carefully that no one was ever hurt. Those people did not have children. What they did have was a strong love of the dog, a boatload of patience, and a willingness to live in a way that causes chronic stress. The quality of life for the dog must also be considered in these situations.
Rescue: I list this as an option mostly because so many people think a rescue might be the answer. Having been involved in rescue for many years, I can tell you that no group wants to take in an aggressive dog. Think about it: How will they adopt the dog out? There would have to be months of behavioral rehabilitation, assuming the rescue even had a trainer on hand. Even then, should the dog be adopted out and bite someone, the organization could be liable. Besides, during those months of training, a number of other sweet, deserving dogs could have been occupying that space. Believe me, we all wish that magical ranch where dogs run free existed, but it doesn't.
Euthanasia: This is the option no one wants to think about. Unfortunately, in some cases it does end up being the right alternative. That said, I have never in 20 years of behavior made the call as to whether someone should euthanize their dog after only having read an email or having a phone conversation, despite the fact that I have been asked to do so numerous times. No owner should ask for help with that type of decision without a thoroughly qualified behavior specialist seeing the dog in person.
One more thing: I have heard people discuss extracting a dog's canine teeth as a solution for severe aggression. Seriously! Sure, the dog wouldn't be able to cause as much damage, but this is not a solution. The dog would still experience the emotions that went along with the aggression, so the underlying problem wouldn't be solved; another dog could attack and the dog would not be able to defend himself; and the chronic stress the dog is under would likely eventually cause the dog physical illness as well as emotional distress.
Of course, in the best of all worlds, a trainer would be consulted before the aggression issue gets to the severe stage. (For trainers, check out http://www.apdt.com.) Interview trainers carefully to get a feel for their methods and experience. If you work with a trainer who does not seem to be a good fit, find another. A veterinary behaviorist is another good option. (Please note that many veterinarians do not have extensive training in behavior; an actual behaviorist is recommended.) My heart goes out to anyone who is dealing with this issue. Be sure to discuss options with a qualified professional who can help you to make the right decision.