Animal Welfare Professionals

So, I adopted a dog (2 years old) about 5 days ago. Day 1: he was super sweet, got along perfectly with my other dog (who is 10 months old), had no issues with aggression at all. I even took him to the dog park and he was playful with the other dogs. All the way up until day 4/5 he was really sweet, but the last 2 days I’ve had him he’s developed some extreme aggression. He has lunged at other dogs at the park and even chased them. He growls at almost every dog that tries to play or comes near him. He wasn’t aggressive at all when I first got home a few days ago. 

Maybe I took him to the park too early? Since he’s older maybe he needs more time to get comfortable in my home before going to the park? My puppy acclimated to her new surroundings very fast, so I didn’t pay any mind to my new dog. Maybe that’s where I messed up. 

Since then I have stopped taking him to the dog park and am going to just let him hang with my other puppy and get used to my home and the super familiar surroundings. 

Please give me tips or suggestions on how to introduce him to other dogs, when would be a good time to start this, and anything else to help him adjust to his new home. 

I don’t want to be the reason he develops any bad doggo behaviors! 

Dog parks can be tricky. Not all dogs like dog parks - it can be very overwhelming even to dogs that are friendly with other dogs. Many times there are inappropriate dogs at the park that might bully others. I would recommend getting to know your dog and giving him time to acclimate to his new surrounds and home before exposing him to new experiences that might potentially be "scary". A good rule of thumb is to wait about 3 months before taking him to a groomer, dog park, friend's homes or to doggy daycare. By then you will be better able to read his body language and know when he is having a difficult time adjusting to a situation. If you do go to the park, avoid going during "peak" busy times.