Why would our German Shepherd Dogs temperament suddenly change from placid to aggressive?

He is nearly 3 years old and the most times it's towards my wife it could be something simple like passing the phone between each other he starts to growl then lunges and tries to bite.We have had him since he was 12 weeks old

in what circumstance?if they were not socialized and a stranger walked in the door, perhaps.if a dog they disliked crossed their 'territory' and he was not trained well, maybe.sign up for some obedience training and you wont have to worry.

Usually a sudden change like this is a sign that a dog isn't feeling well or is in pain or distress for some reason.They can't tell us how they feel, so they try to show us. If your dog is showing any other symptoms such as weakness, limping, loss of appetite, vomiting or diarrhea you can probably hazard a guess that she's sick. If you can't see anything, then it's possible she has an internal problem of some sort.Only a vet can make a diagnosis and I'd strongly suggest that you have her examined right away so that you can figure out why she's suddenly acting this way. Dogs don't just become 'aggressive' for no reason, and if it's not a health problem then it could be that she's had some sort of experience that has severely frightened or upset her. Again, a vet is the best person to talk to.Best of luck, hope she's doing much better soon

could be the heat. could be not feeling well. could be if it is addressed to a particular person that that person has tormented or ill treated the dog previously. If it has had puppies , there are lots of reasons and not enough information with regards to age and circumstances regarding the aggression.

As the first poster stated, you left alot open.Under what circumstances does he/she become aggressive? With family members...or strangers?How old is your GSD? Has he/she been properly socialized?Sounds like you have a problem on your hands. Is he neutered? If not, that would be my first step. Some un neutered males can become dominant/possessive of one member of the pack ( you). I would also suggest contacting a professional trainer to work with you AND your wife. Your GSD needs to learn their are 2 bosses in the house and that he is NOT alpha. Find a trainer that specializes in dominance issues and be sure that your wife does as much work with him as you do and be consistent.

dogs are usually like tis out of frustration, either not walking enough, or if its not been seen to, alot of hormones running round with very little to do. but could be a number of things, if you can give a bit more info might be able to help a bvit more

What u said there is a perfect opportunity to do a little training. Get your dog to sit, before you pass the phone tell him 'stay'. Reward him. Go to pick up the phone and let him see it with it in your hand. Reward him. Now before you lean to pass the phone tell him stay and reward him. This should start to give him the idea that he can look but not touch. If he goes for your arm, get him back into the sitting position immediately. That didn't earn any rewards. Try the same thing again you were doing before he lunged. Keep at this and reward him for every stay. Dont reward for the moving, correct him instead. He will get the idea. Your best bet is to seek a trainer. He will also need some mental stimulation, go out with him, play retreiving games and hide and seek. The little training every day is vital to his mental health. He will be a much calmer dog when he does this with both you and your wife. Xxx

You STILL haven't given anything like enough detail.• As he is in the 10-months-to-3-years period in which under-trained pooches firstly act like tempestuous teenaged humans, challenging all authority, then take over leadership of the house, one possibility is that he has decided that he has superior status in the household pack than does your wife. You gave us no details as to how many levels of obedience he has graduated through, who trained him, whether he normally obeys your wife without hesitation.And you gave us only one example - and were horribly vague about that. Consider the WAY the phone is passed. Consider whether he reacts differently depending on WHO it is being passed to. Is the phone being passed ACROSS him, so that your wife leans low across his head or neck or body? Are you the sort who is constantly denigrating your wife, or have taken to shouting drunkenly at her, so that your dog has no respect for her?• It is possible that he is a mild epileptic - it is SHOCKING how many British "breeders" have in-bred and heavily line-bred on certain producers of epilepsy - when the pedigree of an epileptic taken to the Breed Council has been traced back, over 100 appearances of the most notorious of those producers have been found. Most fits occur while dogs & owners are asleep. If he has the kind of petit mal known as "absences" you wouldn't be aware of them happening right in front of you, except that he sometimes seems clumsy, bumping into things he would normally pass smoothly. He may or may not need medication. But you will need to be aware that he sometimes will be briefly blind & deaf, and will be confused when his senses organs switch back on, so would defensively think that whoever was now looming over him instead of being where they were before his sensory organs "blanked out" is intending to attack him.• It is possible that he has a brain tumour. In which case he will become more and more unpredictable and need to be euthanased.A vet, with the ability to see & test your pooch in various relevant ways, will have trouble deciding which, if any, of those applies. Yet YOU expect US to do it based on just the dribble you have supplied????◙ Add http://pets.groups.yahoo.com/group/The_GSD_Source to your browser's Bookmarks or Favorites so that you can easily look up such as rescue groups, feeding, vaccinations, worming, clubs, teething, neutering, size, diseases, genetics.◙ To ask about GSDs, join some of the 400+ YahooGroups dedicated to various aspects of living with them. Each group's Home page tells you which aspects they like to discuss, and how active they are. Unlike YA, they are set up so that you can have an ongoing discussion with follow-up questions for clarification. Most allow you to include photos in your messages.Les P, owner of GSD_Friendly: http://pets.groups.yahoo.com/group/GSD_Friendly"In GSDs" as of 1967