What is Littermate Syndrome? This term encompasses a range of behavioral challenges that may present themselves when siblings (or young pups of different litters) come home at the same time and are raised together. While the concept is anecdotal rather than evidence-based, I think it is a subject worthy of discussion and attention (and hopefully future research). Some of the commonly-seen issues may include:
- Poor socialization! While it may seem that the pups are getting extra playtime with each other, having two of them means that it is all the more difficult to manage taking them out of the house to socialize with the rest of the world. They are also more likely to just pay attention to each other rather than the new faces/events/places around them. They may fail to learn strategies to form relationships with new people and new dogs.
- Hyperattachment! If the pups’ owners don’t take special care to allow the puppies time apart from each other, they can easily develop attachment issues between them. This may result in the puppies getting anxious when they’re apart, even well after they reach adulthood.
- Training Deficits! It’s far harder to train two pups at once than it is to focus on just one. This means that their owners may struggle to train all of the basics with both of the puppies, when they would have had more success with just one of them.
- Aggression/Infighting! It’s unfortunately common that as littermates develop, their play may become overly rough and their squabbles become dangerous. It’s common that these pups share spaces, toys, chews, and other resources, which are all areas of concern regarding dog-dog aggression. When pups go through puberty and young adulthood, the additional hormonal fluctuations also factor in to this problem.
Patricia McConnell, PhD and expert in animal behavior describes Littermate Syndrome: “It seems harder to get their attention, harder to teach them emotional control, and harder to teach them boundaries.”
The moral of the story? It may be wise to wait until your first pup has had time to develop before adding another.