mastiffs bad behaviour!!

[Antonia]

Hi, Im new on here and wondering if anyone can offer any advice or insite to my mastiffs behaviour change.
I will try and not ramble on too much!
My boy is 22months I have had him since a pup he has always been very freindly and gentle with everyone he meets....Untill about five months ago when he became agressive to anyone who came to the door. Growling and lunging at them. He was ok if kept away till visitors had entered the house and sat down then he would give them a good sniff and be fine. Only his behaviour has become worse. He is fine with me (very submissive )fine with my close family and two young kids. But anyone else who comes into the house he charges! He has not bitten but charges and leapes on people, including children!! Even children he has known since he was a pup and played with. I find this very worrying so am forced to lock him away at present when anyone is in my home. I know this will not help the problem. I have been trying to buy a muzzle for him to wear so he can be out when people visit but can not find one in the uk and so I am awaiting one ordered from the U.S!
If I shout at him when he charges people he stops and backs down but the second I relax he will do it again! He has now started this behaviour when I walk him. Some people he is freindly with some he will lunge at aggressively.
Up and till this problem he was fine with everyone went everywhere with me. If at the park all children including toddlers could approch him and he would be very freindly.
I want to get to the bottom of this behaviour and improve it so he can have more freedom again.
He is uncastrated and my vet suggested a hormone implant that stops the testostorone for a year but his has given very little improvement. Now my vet has suggested seeing a behaviourist.
He has always been fairly nervous of new experiences and loud noises so I dont know if it may be a fear response?
I am baffled as up untill now he was a soppy gentle giant and still is with people he knows.
If any one has any thoughts on this I would love to hear them.
Thanks for reading my ramblings!

[shontelle1985]

Hello. I dont know if you've read any of the previous threads on the forum, but there is a story on here about a Mastiff who got gradually more aggressive and eventually attacked a stranger after previously attacking a family member of his owner. His owner did the responsible thing and had him put to sleep rather than pass the problem on to someone else as alot of people do. She was undertandably devastated. This is obviously something you you want to avoid so I would follow the advice from your vet and seek help from a behaviourist. There are a million different ways of dealing with aggression, it sounds as if you really need help with your boy. Its a blessing that he is still good as gold with you and your family. I'm sorry I have no practical advice, your story just reminded me so much of the one I mentioned, I really hope there is a happy ending for yours.

[Mastiff]

Please don't do anything in a hurry, he may just be shy and DO NOT leave him unattended with children.
Forgive me for asking is he a mastiff or a neo, dogue, bullmastiff look on the KC registration form.
Your first port of call should be his breeder, a good breeder supports you throughout you dogs life. Do not go to an animal behaviourist without a personal reccommendation. I will mail you privately

[Mastiff]

Your e-mail is not available on your application under the name of Antonia without this I can not offer you further advise.
You could mail me on oemcforum@gmail.com
LS
Web Manager

[birdman]

hi antonia , sorry to hear that milo is experiencing a drastic change in behaviour as he was such a gentle boy,
to a point im glad he is showing no aggression towards your two children,but its very strange for him to be this violent , could this be an extention in behaviour of possibly being teased and goaded from out side of the fence , also several of the other mastiff sites have put forward the possibility of a thyroid problem when sudden aggressive behaviour crops up , so maybe some blood tests doing if not already done by vet , hope it goes well
regards
dave , bo & dillon

[Antonia]

Thanks to all who have replyed about this.
He is a Kc registered mastiff. I never leave him unattended with children. I wouldnt leave any breed of dog alone with children. Although he is very gentle and patient with my own kids.
The behaviourist recommended to me by the vets is the dog behaviour center at Staines. I dont know how experienced they are with mastiffs though?
Thanks Dave for the comment about possible thyroid problems. I will get on to my vet and see if we can test for it. It must be a shock to you hearing about his change in behaviour as he was up untill now a big soppy gentle lump!
I will keep you all updated on any progress made.

Antonia.