Cairn Terrier anxiety after new puppy

An 8-year-old Cairn Terrier who's lived as top dog their whole life suddenly having to share the house with a bouncy puppy — that's a real upheaval for them. What you're describing isn't classic separation anxiety so much as situational stress: your older dog is probably fine when left alone as they always were, but now being left with the puppy is the problem. Before I point you anywhere useful, tell me a bit more: what does the anxiety actually look like — is it pacing and hiding, vocalising, or has there been any growling or snapping at the puppy? And how long ago did the puppy arrive?

That's actually a fairly positive picture — the growling is healthy communication, not a sign of something breaking down, and hiding rather than destructive behaviour or constant vocalisations suggests he's coping, just unhappy. Six weeks in is still quite raw for an older dog. A couple more questions: are they left together unsupervised in the same room, or is there separation between them when you're out? And does your Cairn have a space of his own that the puppy genuinely can't access?

Right — that's the core issue, honestly. Your Cairn has lost any sense of control or retreat, and that's what's driving the anxiety. The single most impactful thing you can do is give him a guaranteed puppy-free zone: a crate or pen with a covered top where the puppy physically cannot follow him. That restores his agency. Alongside that, I'd recommend an Adaptil Calm Home Diffuser. It releases a synthetic version of the calming pheromone mother dogs produce, and it's genuinely effective for exactly this kind of situational, household-disruption stress in adult dogs. It won't sedate him or change his personality — it just takes the edge off background tension. Plug it in wherever he spends most of his time. You'd typically start noticing a difference within one to two weeks. Pair it with proper zoning and you should see him settle considerably.

It works for dogs of any age, so yes, the puppy will benefit too — though puppies are generally resilient and less in need of it. The diffuser covers a room rather than targeting one dog, so both will be exposed. That's actually a good thing: a calmer puppy is less likely to pester your Cairn relentlessly, which helps the whole dynamic. One diffuser in the main living area is usually sufficient. If your Cairn retreats to a bedroom or second room frequently, it's worth getting one for that space too.

Most people run it for the first three months after a big household change — that's roughly how long it takes for a new multi-dog dynamic to stabilise. Each refill lasts about 30 days. You don't need to use it indefinitely; once your Cairn has found his footing and the puppy has calmed down a bit with age, you can trial stopping it and see how he does. The physical zoning — giving him that safe retreat — that's worth keeping permanently. Cairn Terriers are independent dogs and they really do need a space that's genuinely theirs.