Two males or two females may be aggressive toward each other. You can train all you like but never leave them alone together. Sooner or later they will fight and it will be bad. I have a female dog that is aggressive toward one I am fostering. I have another that just rolls over when she gets bad so that has worked out. Finally the big fight occurred and the foster dog got pretty beat up. Luckily the foster dog has grown and is a little feisty herself. Whenever the one gets loose or out, she has attacked the foster dog. Finally the foster dog kicked her **** and the pecking order changed and their hasn’t been another fight. I still don’t trust them together. I try to be careful and have a routine so that they are never loose together. It is a hassle when it is cold outside. Both dogs were used to running free and will take off when let loose or a door is opened. The problem becomes walking the other one until I can finally capture the other. It’s work but they are both rescued and they wouldn’t be alive if someone hadn’t taken them in. Your doing a really good thing by fostering. It is very hard to recondition dogs so that they are adoptable by other families. They want and need the love you offer but need to learn how to exist with care. I cannot get either one of these dogs not to run when loose so I’ve adopted them, hassle and all. I did put a, can’t think of the word, cross-hatched wood door up. Went to HD and bought the stuff and some 1×4s to frame it. You can see thru it and it separates my LR from my kitchen. I switch critters around as needed. And I put runners up outside so I can switch them around as needed and they still get exercise and fresh air. It’s worth it.

You cant stop aggression you can only change the enviroment and the “Pack” life. Male dogs and females both are territorial. You male is feeling intruded apon. He is protecting you and the female. The thing is you need to watch the behavior of the other dog. Is he fearful or is he dominantly behaving? He could be sending out signs that he is dominate, even if he is sick, to you male. Unless you very keen on doing many hours of work between the two I suggest keeping them apart till the sick dog is better. Also what is he sick with? Its not a good idea for the dogs to be together anyway if he has an infectious disease. Why put your dogs at risk? If he is just injured then again keep them seperated till he is fully healed, because constant threat and aggression will not help his healing time. If he is a foster he may not be the best idea for your household. If you plan to keep him you need to get help with your male dogs aggression maybe a trainer advice.

just be carefull when dowing this ok make share that you dont have kids about

You need to get control of your household. A trained member of the pack will look to you for guidance and let you as the leader handle the situation. He’s taken control and feels he needs to protect you and the female from whatever he feels as a threat. Reintroduce training to him and stick to it.

Keep him **********! When he shows signs of aggression, stiffened posture, wide darting eyes, ears back, raised hackles, raising the lip, growling, etc IMMEDIATELY spray him with white vinegar and water, use a shaker bottle or another noise maker. Anything to get his attention focused on YOU right away. Put him in sit and then down. Keep him there untill YOU give him permission to get up! No sooner – whether its 5 min or an hour.

Good Luck

Brush their teeth and show them dignity and humor, they will entertain their senses into mock and complaint, instead of prosecution and crash.

You need to keep them separated – at least for now. First, you’re bringing a new male into your dog’s home, which he doesn’t like. Secondly, the foster dog is sick so he’s not himself either. Ideally, if you could keep them in adjoining rooms with a baby gate up between them so they can see each other and most importantly to a dog, smell each other, they should get used to each other’s scents and become more accepting. You need to keep them separated until your dog calms down and gets used to the foster dog’s scent. Once that happens, they should be ok in a room together – supervised. If your dog is socialized and dog friendly, he should calm down.