Female Agression towards Pup

Question
Hi about 3 months ago we purchased a male boxer pup as our other male boxer had lymphoma and had to be put down. So our female wouldn't fret too much we bought a male to keep her company. Problem is she is very agressive towards him every time he goes near her. She snarles and tries to bite him and stares hard at him. I have had a trainer out 2 times and she had advised training for both of them. I took him to my mum's place as she has mmy boxer females sister and the pup and her got on fantastic together. I walk them together with my daughter on the leash and at first they jump and kiss each other but then she just turns away and ignores him as she knows if she starts with him she gets into trouble. So on leashes they are ok, but if I take him off and he goes near her she starts aggression again.I have them separated at the moment,but this is really hard and i don't know what to do. Please help.

Answer
It sounds as though the female is grieving for her loss and not accepting an alternative playmate.

Dogs do grieve as people do, and a "replacement" was not the answer. It only caused her to resent the replacement pup.

You cannot force her to accept him, and he is so young, all he wants to do is play and socialize with her when she is not accepting him as her lost mate.

She should have taken to him as a substitute mother, but didn't.

All you can do is modify her behavior because she is the aggressor, not the pup.

Buy a whistle. Each time she shows signs of aggression toward the pup, blow it. This startles her and diverts her mindset of aggression in that moment, to a different state of mind. Attention onto you.

Use a simple one or two word reprimand command that you choose to use continually each time (everyone in the household) and be consistent with the whistle and verbal reprimand command.

You can leash her (shows control) and lead her into a time-out crate for a 3-5 minute time-out. Do not use this crate for any other purpose: no crating at night, when leaving the house; do not use for anything other than a "time-out." purpose. You do not want her to associate this crate with any other crate being used for sleeping and time when you leave the house, etc.

A whistle always helps divert a mindset and soon, she will learn the sound of the whistle will lead to being crated for 3-5 minutes and represents bad behavior.

Let me know how this works for you in a few weeks with a follow-up.

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