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Maybe you knew the risks and brought two puppies home anyway. Maybe you inherited a bonded pair from a family member who couldn’t cope. Maybe you were told it would be fine, and now you’re standing in your kitchen at 6am with two puppies screaming in separate crates, wondering what you’ve done.
It doesn’t matter how you got here. You didn’t come here for a lecture. They’re yours now, you love them, yet something feels harder than it should. Or maybe nothing’s wrong yet, but you’ve started reading and now you’re worried.
Raising littermates (whether actual siblings or two puppies of similar age brought home around the same time) is genuinely one of the hardest things you can take on as a dog owner. Not because it’s impossible, but because it asks more of you than almost anything else, and most of the advice out there is either “you shouldn’t have done that” (not helpful) or “just love them both equally” (not enough).
So: what’s actually happening when two puppies grow up together, how to tell if things are heading somewhere concerning, what the work looks like day to day, and where to find help. We’re also not skipping the question most content avoids: when keeping both isn’t the right call.
What’s actually happening (and what isn’t)
You’ve been searching for help and you’ve encountered plenty of dire warnings, heated debates about whether it’s even real, and very little in between.
“Littermate syndrome” isn’t a formal diagnosis. The IAABC has pointed out there’s no peer-reviewed research confirming it as a distinct condition, and that critique is legitimate. You won’t find it in a veterinary textbook.
But the challenges are real, whatever you call them. What matters for you right now isn’t the label. It’s understanding the mechanism, because the mechanism tells you what to do about it.
During the critical socialisation window (roughly three to 16 weeks), a puppy’s brain is forming lasting associations with the world. If your puppy experiences every new thing alongside their sibling, they can use that sibling as an emotional crutch rather than developing their own capacity to handle novelty. The sibling becomes an external coping device. Remove it, and the puppy has no internal resources to fall back on.
This isn’t about them missing each other the way you’d miss a friend. It’s that one or both puppies have outsourced their entire stress management system to the other dog.
It often shows up as a bold/shy dynamic you might already be noticing. One puppy appears confident while the other seems anxious. But separate them and the picture changes: the “bold” one was masking, the “shy” one was hiding. Neither is independently confident. They were borrowing from each other.
Guide dog organisations tested this directly. They tried placing two puppies in a single foster home, organisations with rigorous outcome tracking, selecting specifically for confidence and focus. The result: at least one puppy, often both, ended up temperamentally unsuitable for service work. Every major guide dog programme now has a one-puppy placement policy. When organisations whose entire model depends on producing confident, independent dogs decide dual placements don’t work, that’s worth paying attention to.
“It’s not about them missing each other. One or both puppies have outsourced their entire stress management system to the other dog.”
None of this means your situation is hopeless. It means the challenges you’re facing, or trying to prevent, have a mechanism behind them. Understanding it is the first step toward working with it.
Normal hard, or problem hard?
Two puppies will always be exhausting. But “I haven’t slept properly in three weeks and everything is chaos” and “something is developing that needs intervention” are different situations. Knowing which one you’re in changes what you do next.
When things are hard but healthy, you see temporary protest and then settling. You take one puppy for a training session and the other fusses for a bit, sniffs around, finds a toy, gets on with things. The fussing settles in a few minutes, not an hour. During individual time with you, each puppy can hold your gaze, take a treat, actually process what you’re asking. Their play together is reciprocal: you see role swaps, natural pauses, the ability to disengage when you call them. When they encounter something new, they’re curious about it. They look to you for reassurance, not to each other.
When things are heading somewhere concerning, separation triggers something beyond fussing. Sustained screaming. Frantic pacing. One or both puppies throwing themselves at barriers trying to get back together, not a protest that settles after five minutes but panic that doesn’t resolve. Individual training becomes impossible because neither puppy can register what you’re asking. They refuse high-value food, can’t hold eye contact, scan constantly for the sibling. Play escalates into high-arousal wrestling that doesn’t stop without you physically stepping in: no pauses, no role swapping, no ability to self-regulate.
These patterns typically start emerging between eight and 16 weeks, but the real danger point is adolescence. Between six and 18 months, inter-dog aggression can surface in pairs that seemed merely “close” as young puppies. Same-sex pairs carry the highest risk for severe conflict, particularly females. What looked like sibling rivalry at 12 weeks can become genuinely dangerous fighting at 10 months.
If what you’re reading here sounds familiar, that’s not a reason to panic. It’s a reason to act. The earlier you start, the more effective the work is.
What your days look like now
Practitioners consistently describe raising littermates as triple the work of a single puppy, not double. Each puppy needs their own training, their own outings, their own relationship with you, and you’re doing all of it twice while also managing them together.
The goal is simple even when the path to getting there feels relentless: each puppy develops as an individual who enjoys the company of their sibling, rather than as half of a dependent pair. That rests on three things, separate sleep, separate training, separate outings, and your days are going to be built around rotating between them.
Separate sleep
This is where you start, tonight if you haven’t already. Self-soothing skills develop during independent rest. Two puppies sharing a sleeping space reinforce each other’s emotional dependency through every night.
Start with crates side by side where they can see each other. Over two weeks, gradually increase the distance. The goal is separate rooms, but pace it to what they can handle without sustained distress. A few minutes of settling-in whimpering is normal. Prolonged screaming means you’ve moved too fast: close some distance and try again.
This is also insurance you’ll be grateful for later. If one puppy ever needs surgery or an overnight vet stay, a dog who has never slept alone faces a compounding crisis: illness on top of separation panic. Sleep independence now prevents emergency anxiety later.
Separate training
You’ve probably already noticed this: training both at once doesn’t work. One puppy performs while the other watches. You end up with one dog who knows their sit and one who’s learned that their sibling handles it.
Dedicate five to 15 minutes of individual training for each puppy throughout the day. While Puppy A trains with you, Puppy B goes to a separate area with a lick mat, a frozen Kong, a snuffle mat, something that makes separation predict good things. Then swap. This teaches the waiting puppy that being apart leads to something worth having, and the training puppy that focusing on you is where the reinforcement comes from.
This is also where separate relationships form. Each puppy needs to learn their own name, their own recall, their own cues. They need the experience of being your sole focus. For puppies whose primary social world has been each other, discovering that their human is interesting and worth paying attention to is foundational work.
Separate outings
A puppy who only explores the world alongside their sibling hasn’t developed resilience. They’ve borrowed it.
Three or more solo outings per week for each puppy. They don’t need to be elaborate: a walk to the shops, a different park, a visit to a friend’s house. The point is that each puppy encounters novelty and navigates it with you, not with their sibling as a security blanket. They look to you for cues. They build their own confidence. They learn the world is navigable on their own terms.
Putting it together
In practice, the rotation shapes your whole day. Mornings start staggered: one puppy out for a short solo walk while the other has yard time or a quiet activity. One puppy training with you while the other settles in their crate, then swap. A supervised play session together where you’re watching energy levels, practising recall out of play, making sure things stay reciprocal. Later, one puppy comes on an errand with you while the other stays home. Evenings, they take turns settling with the family.
Some weeks the logistics feel like they’re running you rather than the other way around. That’s normal. You’re running two parallel puppy-rearing operations, not one operation with two puppies in it. The workload is real, and minimising it would be dishonest. But it’s achievable with structure, and the alternative, hoping togetherness alone will sort things out, consistently produces outcomes that take far more effort to address later.
“You’re running two parallel puppy-rearing operations, not one operation with two puppies in it.”
What you’re building toward
The relentless rotation doesn’t stay at this intensity forever. The long view matters when the short view is exhausting.
In the first three to six months of consistent work, you start noticing shifts. One morning you take a puppy for a walk and realise the other one settled in the crate without a sound, not because you managed it perfectly but because they just did. Training sessions get more productive. They’re focusing on you, not scanning for the sibling. You can take one out and the other doesn’t melt down at home.
Around the one-year mark, the shape of your household starts changing. Solo walks feel normal, not like a military extraction. They can visit the vet individually without the one left behind regressing. You notice each puppy starting to seek you out independently, not just when the other one isn’t available but as a genuine preference. The daily structure is still there, but it’s become routine rather than a daily negotiation.
Between 18 months and two years, you start to see who these dogs actually are. The bold/shy dynamic, if it was present, softens. Individual personalities emerge. The quieter one might surprise you with confidence you hadn’t seen before. The bolder one shows steadier, less reactive temperament.
By three years, successful pairs typically look like any well-adjusted multi-dog household. They enjoy each other’s company. They play. But they can also be apart without distress, focus on you without searching for each other, and navigate the world as individuals. The structure loosens. The vigilance relaxes.
Not every pair reaches full parallel independence, and that’s not failure. Some households settle into managed co-existence: stable and safe, but with ongoing structure around feeding, sleep, and play. You still separate for meals. You still monitor play sessions. The underlying patterns need sustained management rather than fading into the background. Many multi-dog households operate this way for years, and the dogs live well within it. The question isn’t whether the work eventually ends. It’s whether you’re building toward stability or managing crisis.
The earlier the work starts, the more achievable these milestones are. Dogs who had no early intervention face harder odds. But starting late is still better than not starting.
When things aren’t shifting
Sometimes you do the work and the needle doesn’t move. You’ve been separating consistently for weeks, running the rotation, doing the individual training, and the distress at separation isn’t reducing. Or the signs were already severe before you started and nothing you’re doing seems to touch them. That’s not a reflection of your effort. It’s a signal that the situation needs more than management alone can provide.
Professional intervention changes the equation. Recovery from co-dependence typically follows a general arc. The first couple of weeks are about safety and assessment: physical separation as baseline, finding out whether each puppy can settle in their own space at all, getting enough stability to see what you’re actually working with. Weeks three and four, you start mapping what specifically drives the distress, what triggers escalation, what environments make it worse or better.
Months two and three are the active behaviour modification work: desensitisation to separation, reinforcement of solo behaviours, building the individual skills that co-dependence stunted. The benchmark practitioners look for is that each puppy can manage a 30-minute solo walk without searching for the other dog. Not tolerating the absence, but genuinely engaged with you and the environment.
By months four to six, you’re gradually reintroducing joint activities with structure. The benchmark here: 15 minutes of reciprocal play without escalation to aggression or high-arousal wrestling that can’t self-regulate.
Progress isn’t linear. You’ll have weeks that feel like starting over. The trend line matters more than any single day.
Finding the right help in Australia
The titles in dog behaviour are confusing and the industry is unregulated. Knowing who does what saves time, money, and false starts.
Veterinary behaviourists are the specialists: veterinarians with advanced qualifications in behavioural medicine who can diagnose underlying conditions and prescribe medication where needed. For severe anxiety, escalating aggression, or progress that’s stalled, start here. Search the ANZCVS member list under Veterinary Behaviour for registered specialists.
Behaviour consultants IAABC, Delta-accredited are non-veterinary professionals who design and implement behaviour modification plans. They’re your day-to-day support for separation protocols, training structure, and ongoing management. The IAABC consultant finder filtered for Australia and the Pet Professional Guild Australia directory are searchable by location.
Trainers (PPGA, APDT) handle puppy classes, obedience, and socialisation guidance. Important foundation, but for the specific dynamics of co-dependent pairs, you generally need the tier above.
Most university veterinary hospitals (Sydney, Melbourne, Queensland, Murdoch in WA, and Adelaide) operate behaviour services as referral centres. You’ll need a GP vet referral, but it’s worth the process for complex cases where multiple factors are intersecting.
Initial behaviour consultations typically run 90 to 120 minutes and cost $350 to $450. Follow-up sessions range from $78 to $200 depending on duration and format. Expect wait times of eight to 12 weeks for sought-after consultants. Book early. If you’re seeing concerning signs, don’t wait until things reach crisis to get on a waiting list.
Avoid anyone using or recommending aversive tools: prong collars, shock collars, choke chains. Anyone guaranteeing results or promising quick fixes. Anyone framing the problem as “dominance” or suggesting you need to be “the alpha.” These approaches carry particular risk with co-dependent pairs, where heightened arousal and redirected aggression are already concerns.
The conversation nobody wants to have
If you need what follows, you probably already know. And you may have been avoiding it because everything you’ve read online makes you feel like a failure for even considering it.
You’re not a failure.
When rehoming is the right call
Veterinary behaviourists encounter situations where rehoming one dog is the most compassionate option available. Not a last resort born of giving up, but a considered decision based on clear indicators.
If your puppies are inflicting puncture wounds on each other. If fights are happening daily despite consistent management, and the pattern is worsening rather than stabilising. Physical safety, theirs and possibly yours, is at stake. Management alone isn’t ethical when you’re dealing with severe aggression that isn’t responding to intervention.
If one puppy has become so dependent they can’t eat, can’t play, can’t function without the other in sight, and progress has plateaued despite professional help and potentially medication. When a dog’s entire capacity for experiencing life has been consumed by a single relationship, sometimes changing the equation is the most loving thing you can do.
And if your own mental health is deteriorating, if the financial strain is unsustainable, if the around-the-clock management is physically breaking you down, that matters too. You cannot help them if you’re collapsing. Recognising your limits isn’t selfishness. It’s honest assessment of what they need versus what you can provide.
If you’ve reached the decision to rehome, the question of which dog stays is best made with your veterinary behaviourist, not alone. They’ll assess which puppy has formed the stronger independent bond with your household, which temperament is better matched to your living situation and capacity, and which dog is more likely to transition well into a new home. In many pairs, the answer becomes clearer than you’d expect once a professional maps the dynamics. The bold/shy roles that developed within the pair don’t necessarily predict who thrives where: a “shy” puppy might flourish as a solo dog with a quieter household, while a “bold” one might do better with an experienced handler who can channel that energy. This isn’t a decision about who you love more. It’s an assessment of who needs what, and where each dog gets the best chance.
What happens after rehoming
What actually happens to dogs after rehoming is often what convinces people it was the right call. The “shy” dog frequently gains significant confidence once they’re no longer living in the shadow of a bolder sibling. The “bold” dog typically improves in focus and human bonding once the sibling distraction is removed. Dogs separated young (before six months is ideal, though later separation still helps) generally adjust well to new homes. Many become higher-functioning adults than they would have been in the co-dependent pair.
“Rehoming one dog isn’t failure. Keeping two dogs in chronic distress because separation feels like giving up isn’t serving either of them.”
Both dogs often thrive once they have the space to develop independently. That’s not a consolation prize. That’s two dogs getting the chance to become who they are.
How to do it ethically
Start with the breeder. Responsible breeders include right-of-return clauses and will want to know if a placement isn’t working. They can vet a new home where the puppy develops as an individual or lives with a stable adult dog as a mentor.
If the breeder isn’t an option, breed-specific rescue organisations are the next step. Groups like Labrador Rescue (operating across NSW, VIC, QLD, and WA) and specialist breed rescues have deep expertise in temperament assessment and matching dogs to appropriate homes.
State-based services like RSPCA NSW’s Rehoming Assistance portal can also facilitate safe rehoming when other routes aren’t available.
Whatever path you take, full transparency about the dog’s history, needs, and behavioural patterns is non-negotiable. The new home needs complete information to succeed.
Where this leaves you
That was a lot of ground, and if you’re feeling the weight of it, that’s reasonable. Whether you’re implementing separation protocols tonight, booking a consultation this week, or sitting with a harder decision, the path forward asks real things of you.
But the framing matters. You’re not surviving chaos. You’re building two individuals. Each puppy in your house has their own temperament, their own curiosities, their own relationship with you waiting to develop. The work of separation isn’t pulling them apart. It’s giving each one the space to become who they are.
If you haven’t started: Start with sleep. Tonight. Crates side by side, with the plan to gradually increase distance over the next two weeks. That single change begins shifting the dynamic.
If you’re worried about what you’re seeing: Book a behaviour consultation now rather than waiting. Eight to 12 week wait times mean the sooner you’re on a list, the sooner you have professional eyes on the situation. The ANZCVS member search and IAABC consultant finder are where to start.
If you’re considering rehoming: Talk to your breeder or a veterinary behaviourist first, not the internet. They can help you assess whether you’ve reached that threshold, and guide the process with the dogs’ welfare as the priority.
And if someone you know is thinking about getting two puppies at the same time, we’ve written a separate guide for that conversation.
