Dog parents may have seen the diagnosis of “littermate syndrome” going around on TikTok and Instagram, but few actually know what it is–and a lot of people are claiming to be experts. We’re giving you the 411 on littermate syndrome so you can keep an eye on your new pup and make their transition into your family as seamless as possible.
What is Littermate Syndrome?
Littermate syndrome is a term used to describe behavioral issues that sometimes arise when two puppies from the same litter (or close in age) are raised together. While not a formally recognized medical condition, many trainers and behaviorists observe patterns like excessive bonding between the siblings, aggression, anxiety, and difficulties in training when puppies are raised together without proper guidance.
Is it a Real Medical Issue?
Yes and no. “Littermate syndrome” isn’t a scientific diagnosis, but it’s a real phenomenon backed by anecdotal evidence and professional experience. The core issue is that two puppies bond so closely to each other that they fail to form healthy relationships with humans or learn to cope independently. Dogs with littermate syndrome may struggle with anxiety, be harder to train, or develop aggression toward one another or outsiders. However, not all pairs develop these issues. With commitment and consistent training, many families raise sibling pups successfully.
How Can You Avoid It?
The best way to avoid littermate syndrome is to raise one puppy at a time. If you’re set on adopting two, be prepared for intentional, structured training:
- Train and walk them separately.
- Crate them individually.
- Give each dog one-on-one time daily.
- Work on independent confidence-building.
These steps help each puppy develop their own identity and resilience.
What If You Suspect It?
If you think your dogs are experiencing littermate syndrome:
- Separate routines immediately – individual walks, meals, and playtime.
- Consult a professional trainer or behaviorist.
- Work on socializing each dog individually to new people, places, and other animals.
While it takes extra effort, dogs with littermate syndrome can improve and lead happy, balanced lives with the right support and training. If you have any questions about your specific dog’s behavior or health, please reach out to your vet!
