Hi,

My young male is 18months old and is increasingly showing more
And more aggression to other males. When we are out he doesn't get let off unless we can see
It is safe to do so and no other dogs are there.
He lives with an 8yr old dog who he has now attacked and punctured on four occasions. Previously it has been over food so they eat well away from each other now. Last night it was over a toy. I could remove the toys but I do think the younger dog will just find another flaming point. I do not want to rehome under any circumstances. I need to find a way around this.
What is the thinking of tardak and suporelin now? Do they think it calms them down for aggression or not.

What breed/s have you got? Some are of course far less likely to be able to live together with other males, and for some breeds I don't think it is worth even trying.

In my experience, Tardak/Suprelorin and also neutering makes a small difference but often not enough, it depends so much on the individual dog. I have one entire male who cannot LIVE with any other male, neutered or entire makes no difference at all, but he is absolutely fine to meet other males for short periods of time, such as at shows. I have two other entire males that both live with neutered dogs no problems but do not generally accept other entire male dogs.

You need to keep the two separate when you cannot supervise, both for the sake of making sure nobody is injured, but also the more fights there are, the worse it will get. I never keep any dogs of the same sex together when leaving the house of my Malinois (the Papillons are different), even if they have never had a problem with each other, as I know this breed CAN easily develop problems with their own sex -both dogs and bitches.

They are both giant breed. The young male had grown up with the older one but uts been the last 3 or 4 months that he has started getting aggressive. The older male is neutered.

They are both separated when we are not in. I do have a kennel too that could be used but it defeats the object if him being a pet. As the fights have started when we are at home anyway.

Sounds like the male is approaching hormonal, if not complete, maturity and it may be a case of deposing the older dog- spats over resources etc.. Puncture wounds indicate he means business. The only thing that may be slightly odd is that your older dog is castrated- so not necessarily a straightforward competition for the best of everything. Was your older dog castrated late?

Has your older dog seen a vet recently and can you discount an underlying medical condition that might prompt the younger dog's behaviour? Equally, does younger dog have a completely clean bill of health?

You say he is reacting to other dogs outside, is this any dog or is there a pattern , whether sex/neuter status, size, type etc..?
It could be a learned behaviour that has arisen fro some reason with your older dog and is now generalising, or if intact male specific it is more likely hormonal. Need to figure out if this is defensive/fear, learned bullying/resource control or competitive hormonal.

I would not leave these dogs alone at any time and I think you need to be very clear that you control resources and supervise all their interactions and ensure you are totally even-handed. It might be an idea to have someone in to help you figure out what is going on.

The only thing that may be slightly odd is that your older dog is castrated- so not necessarily a straightforward competition for the best of everything. Was your older dog castrated late?

It happens anyway. :( One of my entire male dogs very nearly killed one of my neutered dogs. It was touch and go for a full month before we knew the neutered dog would even live. The neutered dog is bigger (about 10 kgs heavier), 4  years older and was neutered at 5 months.

Goldmali,

Yes, that is true, although I tend to think such an early neuter can make a dog behave in ways that are deemed inappropriate/weird for an adult dog, at least in the eyes of other adult dogs..if you see? As we know, weird behaviour can prompt a bullying/feather plucking/murderous frenzy in the other animals. Awful but true.

For the other person, I really feel that serious aggression, that involves puncture wounds, should involve professional intervention before it all gets out of control and to ensure the real reason is nailed down. Castration may help, or make it worse, or have no impact at all, so it is vital to try to find out what is going on.

Yes, that is true, although I tend to think such an early neuter can make a dog behave in ways that are deemed inappropriate/weird for an adult dog, at least in the eyes of other adult dogs..if you see?

Yes I fully agree, and it was a big mistake made 12 years ago never to be repeated -I was just making the point that even if NOT neutered late, some entire dogs can take against neutered dogs. This boy who was neutered young, he took until the age of 3 before he started to act like a male. I didn't think he ever would (which is WHY he was neutered so early) but aged 3 he suddenly started cocking his leg and then he also mated and tied with a bitch in season, so it was like his development was just halted for a while, then he still turned into a "proper" male.

Goldmali,
Fascinating! So one asks how did that work? Was his brain already masculinised enough in the uterus? Did he 'learn' how to be a male from observing other intact males in the group, was he in some way affected by their testosterone? This stuff is so interesting because one would really think that neutering at such a young age would stem any possibility of proper, adult male interactions. Study please!

Edited to say that I seem to recall that early neutering can also produce hyper-sexual behaviour, amongst other things, but that is slightly different from what you describe.

Back to the OP, I really think get a behaviourist in and they should do a 360 degree appraisal and history to ensure you nail down reasons for attacks, only then will you really know how to proceed long-term. If nor bred by you would the breeder of your younger male have any comments/observations? 

The breed here is key, there are many of the more guarding, dominant, reactive breeds (like terriers) and some primitive types who cannot be relied on to be sociable with their own sex, despite having sound temperaments.

It's worth a try, however from my experience it made no difference and it got to the point where it wS too stressful for both dogs and humans to live like this. I had in behaviourists and tried many things but nothing worked. The dogs couldn't be together due to the younger one attacking the older one.

I think you need to get a decent behaviourist in to observe the dogs first hand and work out what is going on, and how best to deal with it.  There can be myriad little signals between them, body language, gestures and so on that would indicate a particular issue.

You say they are a giant breed - can you specify?  Giant breeds vary greatly - some are very gentle, others are VERY hard work and barely domesticated.  What they are could have a significant bearing on the situation.