Second trimester · Days 22–28

Week 4 of dog pregnancy: confirmation window

Embryonic sacs are about the size of a walnut. Heartbeats can be seen on ultrasound from about day 25.

Updated October 2026 · Information only, not veterinary advice

What you may notice

  • Nipples larger and pinker.
  • A thin, clear mucus discharge.
  • A smaller appetite or mild nausea in some dogs.

Care and feeding

Her nipples may enlarge and turn pink. Keep her diet unchanged unless your vet advises otherwise.

Keep her current diet unless your vet advises otherwise. Offer small, tempting meals if her appetite dips.

Vet this week

Abdominal ultrasound at about day 25 to 30 confirms pregnancy and heartbeats. It is not reliable for counting puppies.

Questions

Frequently asked questions

Can the ultrasound tell me how many puppies she has?

Not reliably. The uterine horns coil and overlap, so puppies can be missed or counted twice. An X-ray after day 50 gives the count.

Is clear discharge in week 4 normal?

Yes. A thin, clear, odorless discharge is common. Green, bloody or smelly discharge is not and needs a vet.

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