Hi i am new on here, we have had rotties for 15years we are just pet owners, never had any problem at all, all been super family pets, until my male rottie shocked me completly the other day, he has never ever shown any signs of aggresion towards any other animal or person, but we were in the vets he was sat down sniffin around looking around calm as you like until this poor unsuspecting cocker spaniel came in and he lunged for it and almost tried to kill it, i was so shocked it was completly out of the blue, dogs were coming and going its not as if it surprised him, i just cant understand why he did this, we used to let him off playing with other dogs on the beach and park and now i am terrified, he will do it again but he will hurt something, he isnt even scared of the vet, loves the attention, i really cant understand it or know how to deal with it, he hasnt since shown aggresion but i havent let him off his lead, i have enrolled him in classes and are going to start him with agility, he is only 11months old, but hes big and i dont want to add to the irresponsible owners who give these dogs their bad reputation,
thanks

Not an excuse but a reason maybe, did the cocker challenge him, was it male.

Your boy is at the ultra hormonal stage going through puberty.

Lots of training to keep his mind occupied and to make obedience and respect of you second nature are a good idea at this time.

welcome! maybe he misread the dogs signals? or not as brainless said, it could have been challanging him. just try and keep him having possitive times with other dogs, and try not to get nervy about it when other dogs approach, he'll pick up on it and might react to that. let us know how your getting on with it. i know how distressing it can be, especially with a big breed with a rep- not only scary but mortifying, you don;t want to be "one of those owners"... you''ll do fine! and you;ll find plenty of support on here

It's easy to forget the power our "babies" really have isn't it and when we see it in it's raw state, it can come as a real shock. You might be overeacting to the unknown. He perhaps overacted to the fact that he was at the vets and wanted out at any costs. Did he actualy make contact with the other dog and do damage, or do you think he would of killed if he had?

I was reading this post with dismay until I read his age and then was relieved. At 11 months he's well and truly into the most 'manly' phase of his development. The fact that he's shown no temperament problems so far, and I guess is an other-wise well balanced lad, suggests that the outcome looks promising.
As Brainless said, train through this hormonal phase and above all, try to avoid letting him get involved in situations which may have a lasting impression on him at this sensitive time. He may fancy a go at being a 'hoody' so you need to show him that it's not on.
Training -avoidance - patience. All things you will be good at as experienced Rott owners. Good luck.

Thank you so much for all your insight, i am a bit more relaxed now! Although i must point out that the spaniel was in fact a girl, and as far as i can rememeber the poor thing never even looked at him she was too busy jumping all over her dad! And also he didnt actually hurt this spaniel he just completly lunged for it with a growl as deep as his boots if you can call it a growl it was more like a roar, And to tell you the truth i dont if he would have hurt her, i cant say, i would like to think not but wouldnt that make me irresponsible? Same as i have said i have had this breed for a number of years and i know they can be unpredictable, but i have never had one that took it to this extreme, and i think this is maybe one of the reasons it has shocked me so much. Do you think it could have been the fact that the spaniel was really giddy?, could he just of been telling her to chill? Well i dont know, but i will let you know how buster gets on , he is now enrolled in classes and starting agility, and i know he will love it!
thank you all

roxie and busters mum x

glad your feeling a wee bit better. your not being irresponsible, from posting and obviously being worried your clearly not being complasent, your just hoping for the best. he might have been more stressed about the vets than you realised and over reacted to her bounciness. see how it goes, just be careful and patient. good luck!

First off at 11 months old your male Rottie is getting abit hormonal and his attitude will start to change, this is where you keep on with the training and make sure he keeps his manners!
The one thing is slightly worrying is that you say you have owned Rotties for 15 years and you know they are unpredictable!!!!  We have owned Rotts, GSD's and Akita plus many others for over 20 years and I would never say a Rottie is an unpredictable dog.  My 16 mth old male Rott is getting a little more bolshy because of his age but he is constantly reminded of how to behave and because of this he can meet and greet anyone and any dog and is good as gold.  He does however get very excited and can also be vocal...this is natural behaviour of a Rott who wants to play. 
Are you sure it was aggression or was it an over excited boy trying to play and making alot of noise about it???

firstly hello, and thanks for your reply, however i said rotts can be unpredictable not are and this is usually more common in males, that doesnt mean they are all nasty unpredictable, When we got our first rott we were  advised to have a bitch as our first dog, that was one of the reasons and this was also confirmed in the many dog and training books we used at the time, and i also stated that this is why it shocked me so much because we had never had a problem like this ever. And i could tell he wasnt over excited and wanting to play i know the diffrence, he had never ever lunged and made the awful growling that he made ever before! We like to think of ourselves as responsible rottie owners, and i have not had this before, i am looking forward to the classes with buster and i am sure he will excel in the agility, thanks for all your comments and suggestions they are all helpful, and i am glad to report a nice calm walk on the beach this afternoon and buster did exceptionally well, he had fun and i wasnt as wary, thanks
roxie and busters mum x

Well done. Your going about this with a calm and considered way, which I'm sure he'll pick up and it will maybe never happen again. Let's face it, they are all capeable of snapping when stressed, what ever the breed.
Good luck and enjoy your new classes.

It may well have been the situation he was in at the time, sometimes smaller dogs that move around quickly can un nerve bigger dogs.  I'm glad you went out and had a nice calm walk with him today.  Good luck with the training classes and hope all goes well with your boy.

Even a wrong glance from a dog can set a guard dog off, to him he was just protecting from what it sounds like, and if he is in the puberty stage, he will need an extra shaper eye kept on him! But if he's not aggressive in nature I wouldn worry too much.

you say the other dog was "jumping all over its owner" i think that might be the reason, if your dog has ben taught this is wrong he may have been trying to tell the other dog off. not his job i know but he doesnt know that yet. i have to watch my big dog also if another dog is behaving in a mad way as he feels the need to step in. x

Thanks for your interest, however i have another small query...i know i should trust my new dog trainer but today she advised me let buster off his lead on the beach with a great assortment of other dogs running about she said she wanted to evaluate his responses? I decided that i really didnt want to do this because i didnt feel comfortable with it, it felt very irresponsible? He was jumping about and he was making the play noises, but however i did not know whether he was going to do something wrong!! I wouldnt have been able to cope with it, do you think she was right or should i be looking for another trainer?

I don't know whether you would get the same response from your dog when there are lots & lots of dogs around. In my limited experience my GSD Zak behaves very different when confronted by a number of dogs, than when it's a one to one situation. At agility shows & training he virtually ignores other dogs, at home on his own territory he fixates on dogs coming towards him & almost goes into a crouch position. He does pass most dogs without a problem, but will try & lurch towards any that bark at him. If you don't feel comfortable with this situation, you know your dog & if your gut instinct tells you not too let him loose, don't back down. Does your trainer have experience with rottweilers, if not, I would suggest you change to one that does.

not sure about the training aspect with this, but i;d feel pretty uncomfortable about it to... i imagine it feels a bit like inviting trouble.

I'm not sure if I have read this correctly so forgive me if I have it wrong but should you be doing agility with him if he is only 11 months?? I have enrolled my dog [he is a Brittany and thus much lighter boned than a Rottie] but they wouldn't let him start untill he is 14/15 months as the bones and joints are still growing.