* Puppy's Immune System: Puppies at 3 weeks old are still very vulnerable and their immune system is developing. They haven't had their first set of vaccinations, making them susceptible to infections.
* Socialization: Before 8 weeks old, puppies learn essential social skills from their littermates and mother. Introducing other dogs too early can disrupt this crucial learning period.
* Play Style: Puppies at 3 weeks are still learning to play gently. Older dogs might unintentionally be too rough, leading to injury or fear in the puppy.
Here's a gradual introduction process:
1. Scent Introduction: Before the first meeting, swap blankets or toys between the puppy and your other dogs to allow them to get used to each other's scent.
2. Supervised Meetings: Start with short, supervised meetings in a neutral area. Keep both dogs leashed and allow them to sniff each other from a distance.
3. Controlled Play: If the initial meetings go well, you can gradually allow controlled play in a safe, enclosed area.
4. Observe Carefully: Watch for signs of stress or aggression from both dogs. If you see any, separate them immediately.
It's crucial to:
* Monitor closely: Even with careful introductions, you should always supervise interactions between your dogs.
* Be prepared to intervene: If necessary, use a firm "No!" or separate the dogs.
* Consult a veterinarian or professional dog trainer: If you have concerns or the introduction doesn't go smoothly, seek professional guidance.
Remember, every dog is different, and some may need more time to adjust than others. Be patient and let the process unfold naturally.