Our family has a 9 year old maltipoo and purchased a 13 week female yellow lab. The second day our maltipoo was just walking by her and the lab got very aggressive with her. And did not back down.
Hi @Sadie girl I guess your question is what should I do about the puppy's behaviour? 1. Teach the puppy to love the crate. When the puppy is in the crate, the adult dog will get some respite. 2. Don't label the puppy aggressive. There is too little time to tell wether the new dog is aggressive, or just doesn't know how to play properly. 3. Put the puppy on a houseline. You can use that to separate the puppy from the adult dog. Ideally find toys, tug toys, treats to entice the new dog towards you. You have to become the centre of attention. The dogs can play together but you are the conduit for the play. While you cuddle the older dog, throw say a ball to entice the pup to chase the ball. When the puppy plays with you and the ball, throw a ball for the adult dog to play with. Use the houseline to constrain the puppy from chasing the ball meant for the adult dog. Alernatively let the dogs have individual turns at sniffing a treat 'salted' snuffle mat. The primary goal is to teach the puppy to be calm rather than aroused when around other dogs, and your other dog, in particular.
Your puppy is not 'aggressive'. 13 week old puppies are not "aggressive" in the situation you describe. Instead, your lab sadly has a very different play style to your existing dog and you will need to think very hard about whether you are up for managing the two together. Some breeds are not ideal co-habitants. With a Maltipoo, you have an elderly fluffy small dog, whose play style will be light-contact, with similar-sized dogs. A Maltipoo is not going to appreciate full-on wrestling with another dog's mouth around her neck. That's just not what that type of dogs likes in play. Your lab, is a typical lab. As such, she probably likes to play extremely roughly, to chase and then slather all over another dog's neck, and (without careful supervision and raising) may treat another dog like an object or toy, rather than a being with his own play requirements. This is not a combination to get without thinking through fully how you are going to supervise them, have them together around the house and have harmony. You are going to need to constantly supervise CLOSELY any time the two dogs are in the same room and reachable by each other. You will need to have the puppy on a 2.5m house line, and hold the pup out of reach of the other dog - hoping that the Maltipoo will come forwards to interact with the pup. If the Maltipoo doesn't choose to do that, then allowing the pup to reach him will not result in a good outcome. You will only terrify him more. Any time you are not around to literally hold the end of the house line and give the situation 100% of your attention, the dogs should be separated by a stairgate or 'crate and rotate', with one dog crated and the other out. I would recommend you really think long and hard about whether you are up for the close supervision and separation and gradual integration that is going to be involved - for probably months - particularly if you have only just got the lab.
We had similar problems in the beginning. We have a 6 year old Shi Tzu, and a now 20 week old Lab puppy. In the beginning I really had huge concerns if the both of them would ever get along. The puppy would pounce on the other dog, would drag him around by his tail, bite at him, body check him, just not playing nice at all. She now has learned that he will only play with her if she plays nice. She will get down to his level now, and even roll over on her back and they play together just fine now. Something that has helped us tremendously was continuously taking the both of them out together for fun activities. I think you need to get them used to eachother outside of your home first, and you will see a huge difference. We also took our puppy to puppy class, puppy play time, and doggy day care to get her used to being around other doggies in a safe environment. GOOD LUCK!
