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Aggressive JRT towards other dog in household
We have had our JRT for 4 years and a year ago brought a german sheppard puppy into the household. Up until a month ago they had gotten along with the Jrt being the boss. We got the JRT fixed about that time and ever since he has been very aggresive towards the sheppard who is now a year old. The sheppard never starts the fights but need less to say the sheppard is starting to defend himnself. We recently got muzzels and have been using for about 2 weeks with no improvement if we take them off when both dogs are in the same room the JRT will go after the sheppard. The sheppard can just be laying down and the JRT will stare him down and then attack. We don't want to get rid of either dog but don't know what to do.