Are they getting enough exercise? Walk them on leash 3-5 miles a day, or at least for 1 hour. A tired dog is a well behaved dog. This method works for my dogs.
The other options are to work with a trainer (I’ve never tried it, can’t afford such things). Also, ask your vet about medication, if only to calm them down a bit so that they will be receptive to training. Sometimes anxiety disorders manifest themselves as aggression.
Or, consider a homeopathic approach http://www.vitalanimal.com
According to the homeopathic vets, over-vaccination can lead to increased aggression.
Dogs under 20 pounds have the most adverse reactions.
