Newborn weights wobble by a few grams from one reading to the next. A puppy that stops gaining or starts losing is a different thing, and the hours matter: VCA warns that a puppy that begins losing weight may die within 48 hours if the loss is not reversed.
This page is for the moment the numbers go wrong: the lines that mean calling your vet, the usual reasons a puppy stops gaining, and what to do, in order. For what normal growth looks like day by day, see our newborn puppy weight chart.
the most a newborn should lose on day one
More than that, or still below birth weight on day two, is a same-day call to your vet. After the first 24 hours, any confirmed loss is a call now.
The short version
- Day one: A dip of up to 10% of birth weight is within normal for a puppy that is warm and nursing. More than that is a same-day call to your vet.
- After day one: A confirmed loss: call your vet now. A full day without gain, still below birth weight on day two, or not doubled by day 14: call the same day.
- Now, whatever the scale says: A puppy that is cold, limp, not suckling, crying constantly or struggling to breathe.
- Call and warm, then feed: Call while you start warming a chilled puppy, slowly. No feed until it is warm; any extra feeding follows your vet's plan.
- Several puppies at once: Look at the dam. When her milk fails or is infected, VCA warns a whole litter can die within 24 to 48 hours.
The red lines: when a weight means calling your vet
Two urgencies run through this page: call now, and call today. The table says which one applies at each age.
Weigh at the same times each day, before a feed, and compare like with like. If a reading is lower than it should be, re-weigh once on the same scale to rule out a slip, then call.
| Age | Normal | Call your vet |
|---|---|---|
| Day 1 | A dip of up to 10% of birth weight in a warm, nursing puppy (many gain from the start) — check it is nursing well | Today: more than 10% below birth weight |
| Day 2 | Back at birth weight or above | Today: still below birth weight |
| Days 2–14 | About 5–10% of body weight gained a day | Now: any confirmed loss. Today: a full day without gain* |
| By day 14 | Birth weight doubled — most by day 7–10 | Today: not doubled |
| Weeks 3–4 | Higher at every weigh-in | Now: any confirmed loss. Today: no gain over a full day or more (same-time readings) |
* Compare readings taken at the same time of day, before a feed; re-weigh once on the same scale to rule out a slip, then call. Cold, limp, not suckling, crying constantly or struggling to breathe: call now at any age, whatever the scale says. Merck Veterinary Manual; VCA Animal Hospitals; Schrank et al. 2020.
The day-two line matters. In a study of 8,550 puppies, those of normal birth weight still more than 8.7% under their birth weight on day two had an observed mortality of 23% by two months of age, against 3.2% for the rest.
Patterns that are easy to miss
Single readings mislead; the pattern across same-time readings does not. Four patterns are worth knowing by sight.
A flat day
"At least it isn't losing" is the trap. After the first 24 hours, a full day without gain between same-time readings means re-weigh once, then call your vet the same day.
Up one day, down the next
Each down day is a confirmed loss — call now, even if the next reading might recover. A zigzag can mean the puppy is pushed off the teat at some feeds, or the dam's supply varies.
Falling behind its littermates
A puppy's line can keep rising while it drifts away from the rest. Compare daily gain as a share of each puppy's own weight, not in grams: a puppy gaining 3% a day while its littermates gain 8–9% is falling behind. Have your vet assess it. The Weight Tracker puts every puppy's line on one chart.
A sudden drop
Any confirmed loss after day one is already a call now, so a sharp drop never waits, whether or not the puppy looks ill. If it is also cold, limp or not suckling, it is the emergency above.
For reading the whole growth curve, see our guide on tracking growth responsibly.
Why puppies stop gaining: milk, warmth, infection, defects, rejection
Poor gain usually has a cause you can find. Knowing the common ones helps you and your vet find it faster.
Not enough milk
- Pushed off the teat. Bigger, stronger littermates push smaller ones off. The rear teats, between the dam's hind legs, generally give the most milk.
- A weak suckle. Puppies born small or after a hard delivery may latch but not draw enough milk.
- The dam's supply. If several puppies are failing at once, look at the dam first. Puppies not getting enough milk cry constantly and fail to gain, and a whole litter can die within 24 to 48 hours. Tell your vet about the dam as well as the puppies when you call.
- Mastitis. An infected gland is swollen, red, hot, hard or tender, and its milk may be bloody or yellow. Infected milk can mean feeding the puppies another way, so call your vet. Infection in the dam is also one of the things that sets newborns up for infection.
Cold
Newborns cannot hold their own body temperature until about four weeks. A chilled puppy nurses poorly, fights infection poorly and cannot digest: its gut stops moving, so milk can come back up and go into the lungs.
Treat a puppy that feels cool to the touch as chilled. In the first week, a newborn's normal rectal temperature is 95–99°F (35–37.2°C).
Keep the area the puppies lie in at about 85–90°F (29.5–32°C) for the first four days, easing to about 80°F (26.7°C) by days 7–10 and about 72°F (22°C) by the end of week four. You don't need to heat the whole room, and puppies huddled against their dam need less.
Newborns also have almost no sugar reserve, so even a short time without feeding can drop their blood sugar. That is how a chilled puppy that stops nursing goes downhill so fast.
Infection
Infection can stop a puppy gaining even when milk is there. The bacteria most often behind it are E. coli, streptococci, staphylococci and Klebsiella.
Signs besides weight include failure to suckle, unusual crying, a swollen or painful belly, diarrhea, vomiting or milk coming back up, chilling, and difficulty breathing. Pale gums are a warning too: a newborn's should be pink and moist.
Canine herpesvirus is the one to know by name. It kills puppies mostly at one to three weeks old, grows best at a newborn's lower body temperature, and often runs its course in a day or less. Many adult dogs carry it with mild signs or none.
Birth defects
- Cleft palate. A gap in the roof of the mouth lets milk into the nose instead of the stomach; milk at the nose during a feed is the clue. Your vet checks for it at the first exam, which VCA advises within 48 hours of birth.
- Heart defects. A heart defect can leave a puppy too weak to nurse well. The vet listens for a murmur at that first check.
- Liver shunts. Less common, and usually found later. Shunts outside the liver are more common in toy breeds such as Yorkshire Terriers, Maltese and Pugs; shunts inside it, in large breeds. Signs usually show in young dogs, mostly neurological ones; in a newborn, a shunt is one cause of low blood sugar.
Rejected by the dam
A dam that pushes one puppy away may be reacting to a puppy that is already unwell: some mothers reject, or even kill, a puppy that fails to thrive, has a birth defect or seems sickly. A rejected puppy needs a vet check as well as warmth and hand-feeding.
What to do, in order: call and warm, then feed
Work down this list. Calling and warming happen together; feeding comes after both.
- Call your vet and start warming at the same time. Call now for the emergency signs or a confirmed loss, and the same day for the other lines in the table, with the puppy's weights since birth to hand. While you call, if the puppy feels cool, start warming it slowly over 30–60 minutes, against your body or in a warm box with warm bedding, and do not feed it until it is warm. The warming time is never a wait before calling.
- Put it on a good teat, only if that is safe. If it is warm, can suckle, and the dam's teats and milk look normal, hold it on one of the rear teats between her hind legs and keep bigger littermates off for that feed. Not if milk comes out of its nose while it nurses (a possible cleft palate), or a teat is hot, hard, swollen or painful, or its milk is bloody or yellow (possible mastitis): then feed only as your vet instructs.
- Supplement by bottle on your vet's plan. This is for a puppy that can suckle but isn't getting enough. Warm the milk replacer until a drop on your arm feels about body temperature. Volumes and schedules are in our guide to bottle and tube feeding puppies.
- Tube-feed only once your vet has shown you how. Tube feeding is for a puppy that cannot suckle well enough to take a bottle, and a tube in the wrong place puts milk into the lungs. Never tube-feed a cold puppy. The technique is in our tube-feeding step-by-step.
- Let your vet treat the cause. Depending on what they find, that can mean glucose for low blood sugar, fluids, antibiotics for an infection, and a feeding plan.
Don't wait for a puppy to look sick. By the time a newborn looks ill, there may be little time left: a puppy that begins losing weight may die within 48 hours if the loss is not reversed, and herpesvirus often kills after an illness of a day or less. The scale is how you see it first.
For what happens when decline continues despite treatment, see our guide to fading puppy syndrome. For normal weights at each age, see the newborn puppy weight chart and puppy weight gain targets by breed size. For the weighing routine, see tracking growth responsibly, and for the wider picture, puppy development week by week.
Weight concern FAQs
1How much weight loss is too much for a newborn puppy?
On day one, a loss of up to 10% of birth weight is within normal for a puppy that is warm and nursing; many puppies gain from the start. Call your vet the same day for a loss of more than 10% on day one, a puppy still below its birth weight on day two, or a full day without gain after the first 24 hours. After the first 24 hours, any loss confirmed on a re-weigh with the same scale is a call now, not at the next weigh-in. A puppy that is cold, limp, not suckling, crying constantly or struggling to breathe needs a call straight away, whatever the scale says.
2What if only one puppy in the litter is losing weight?
A single puppy falling behind while its littermates thrive usually has a problem of its own: being pushed off the teats by stronger siblings, a weak suckle, a cleft palate, an infection or another birth defect. Call your vet now — a puppy that is losing weight needs an exam, not just more milk. While you wait, keep it warm, and do not feed it while it is chilled. Once it is warm, if it can suckle and the dam's teats and milk look normal, hold it on one of the rear teats between her hind legs, which generally give the most milk, and keep bigger littermates off for that feed. If milk comes out of its nose when it nurses, or a teat is hot, hard or painful, feed it only as your vet instructs. Any bottle or tube feeding follows your vet's plan.
3When should I start tube feeding?
Tube feeding is for a puppy that cannot suckle well enough to take a bottle — a weak or absent suckle reflex, or too weak to nurse. A puppy that can suckle but is not getting enough milk is supplemented by bottle first, on your vet's plan — unless milk comes out of its nose when it feeds, a possible cleft palate, which needs your vet's feeding instructions before any bottle. Learn tube feeding from your vet before you need it, because a tube in the wrong place puts milk into the lungs, and never tube-feed a cold puppy: warm it first. A puppy too weak to suckle needs your vet straight away.
4Can a puppy that lost weight catch up?
Often, yes, when the cause is found and treated early. That is the reason to weigh every day: VCA warns that a puppy that begins losing weight may die within 48 hours if the loss is not reversed, so a loss caught at the first weigh-in gives you and your vet the most time. How fully a puppy catches up depends on the cause, so let your vet's checks and the scale, not a fixed timeline, tell you it is back on track.
5Should I wake puppies to weigh them?
For routine weighing, no: weigh at the same times each day, just before a feed, so the puppies are already awake to nurse. A puppy that is losing ground or that your vet is watching is different — follow your vet's schedule, including any night-time weigh-ins or checks it asks for. Between weigh-ins, check that the puppy is nursing, warm and settled.
Related Tools
References & sources
- Merck Veterinary Manual. Management of the Neonate in Dogs and Cats. — A transient loss of at most 10% of birth weight is acceptable on day 1; normal gain 5–10% of body weight per day; no thermoregulation until 4 weeks; normal rectal temperature 95–99°F in week 1; rewarm chilled neonates slowly (30–60 minutes) and delay tube feeding until warm, since hypothermia causes ileus, regurgitation and aspiration; minimal glucose reserves; signs of neonatal sepsis and its usual organisms; mastitis in the dam predisposes to sepsis.
- Merck Veterinary Manual. Overview of Canine Herpesviral Infection. — Deaths usually in puppies 1–3 weeks old; the virus replicates best at neonatal body temperature; illness often lasts 24 hours or less before death; adults may show mild signs or none.
- Merck Veterinary Manual. Congenital and Inherited Anomalies of the Liver in Animals. — Extrahepatic portosystemic shunts are more common in toy breeds, intrahepatic shunts in large breeds; signs are usually neurological and seen in young animals.
- VCA Animal Hospitals. Breeding for Dog Owners — Caring from Birth to Weaning. — Most puppies double their birth weight in the first seven to eight days; a puppy that fails to gain or loses weight is cause for alarm (contact your veterinarian), and puppies that begin losing weight may die within 48 hours if it is not reversed.
- VCA Animal Hospitals. Breeding for Dog Owners — Caring for Newborn Puppies. — Rear teats generally give the most milk; vet check within 48 hours of birth, including for cleft palate; whelping-area temperatures by age; signs of mastitis; a litter not getting enough milk can die within 24 to 48 hours; supplementary milk at body temperature; some mothers reject a puppy that fails to thrive.
- Mugnier A, Gaillard V, Chastant S. Relative Impact of Birth Weight and Early Growth on Neonatal Mortality in Puppies. Animals 2023;13(12):1928. — 8,550 puppies followed to two months of age; normal-birth-weight puppies more than 8.7% under birth weight on day 2 had 23% observed mortality by two months, against 3.2% for the rest.
- Schrank M, et al. Bodyweight at Birth and Growth Rate during the Neonatal Period in Three Canine Breeds. Animals 2020;10(1):8. — Bernese Mountain Dogs doubled birth weight at 10.0 days, Tibetan Terriers at 8.7 days.
Further reading: England GCW, von Heimendahl A (eds). BSAVA Manual of Canine and Feline Reproduction and Neonatology; Lopate C (ed). Management of Pregnant and Neonatal Dogs, Cats, and Exotic Pets (Wiley-Blackwell). This article is for educational purposes and does not replace professional veterinary care. If a puppy is losing weight or not gaining, contact your veterinarian.