What the 3-3-3 rule says
The 3-3-3 rule describes the realistic settling-in curve of an adopted dog:
- First 3 days: shock and survival mode.
- First 3 weeks: routine forming.
- First 3 months: real personality emerges.
UK rescue charities (Dogs Trust, Battersea, RSPCA, Many Tears) all base their post-adoption guidance on a version of this framework.
Days 1-3: survival
Your dog has left the only environment they knew (kennel, foster, previous home) and lands in a brand-new one. Expect:
- Off food or only nibbling — completely normal.
- Reluctant to drink. Offer water; don't force.
- Either frozen and quiet, or pacing and panting.
- Reluctant to toilet outside (some dogs hold for 12-18h).
- Stress diarrhoea common.
What NOT to do: invite all the family round, take them to the park "to see other dogs", introduce immediately to resident cat or dog, bathe them. Less is more.
Weeks 1-3: routine and exploration
They learn that food comes at predictable times and you're a constant. Expect:
- Crying or whining at night (especially first few nights).
- Some indoor marking (especially intact males).
- More confident exploration of the home.
- Specific fears emerging: hoover, men in caps, lifts.
- Lingering digestive issues — check with vet if past 7-10 days.
What you do: firm routine (same times every day), short calm walks, positive reinforcement, ignore minor stress-related quirks (but not all behaviour is stress).
Months 2-3: who they really are
Your dog now feels safe and starts showing their actual personality:
- More confident behaviours (might guard a toy, bark more).
- Hidden leash reactivity may surface.
- Real energy level (the "calm dog" might have been depressed; you might suddenly have a sport-keen Spaniel).
- True bond — comes when called, settles near you to rest.
When to call a behaviourist
- Real aggression (not just defensive growling once).
- Severe separation anxiety (destroys the home, won't eat alone).
- Leash reactivity that you can't manage by week 6-8.
- Persistent indoor marking despite full routine.
Look for ABTC, APBC or APDT-registered professionals in the UK. £80-150 per consultation.
How CanAI helps
Set your dog up in CanAI from day one — full timeline of feeding, walks and behaviour notes. Ask the AI chat about specific behaviours (it knows breed, age, origin). The adoption module has more resources. And get third-party liability cover in place day one — most rescues require it.
