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A miscarriage is the loss of a pregnancy before the puppies can survive outside the mother. In dogs it can happen at any point in the nine weeks, it can affect one puppy or the whole litter, and in its early form it often happens completely silently. That silence is worth understanding: many litters that seem smaller than expected, and some pregnancies that seem to vanish, are explained by early loss rather than by a mating that never worked. This guide explains what happens at each stage, the causes vets look for, led by AKC guidance on miscarriage and Merck material on reproductive infection, and exactly what to do if you suspect a loss.
Abnormal discharge at any stage: bloody, green, black, brown, pus like or foul smelling. Abdominal pain, cramping or straining away from her due date. Fever, lethargy, weakness, loss of appetite or vomiting. Nesting or labor behaviour well before the due window. Expelled tissue or a fetus. Some causes of miscarriage can infect people, so handle any expelled material with gloves, wash your hands, keep other dogs away from it, and tell your vet promptly.
In the first half of pregnancy, up to roughly day 45, a fetus that dies is usually resorbed: the body breaks down and absorbs the tissues, leaving no discharge, no tissue to find and often no sign in the mother at all. She eats, plays and looks normal. The loss is discovered only if the pregnancy was being monitored, for example when an ultrasound at day 28 counted five embryos and a later check finds three, or when a confirmed pregnancy produces no puppies and a recheck scan shows an empty uterus. Sometimes the whole litter is resorbed, and unless an early test proved the pregnancy existed, nobody ever knows there was one. This is one reason experienced breeders confirm pregnancies by ultrasound and recheck when something feels wrong, rather than treating a single early positive as a guarantee. Resorption itself is not a disease; it is the body's tidy response to a fetus that was not viable, which is most often explained by a developmental abnormality in that puppy.
After skeletons have formed, a dead fetus can no longer be resorbed. Three outcomes are then possible. The fetus and its fluids may be expelled, sometimes with contractions and discharge, sometimes quietly, and a mother may clean up and even consume material before an owner sees anything. The fetus may become mummified: dried, shrivelled and walled off inside the uterus, causing no illness, and delivered unnoticed alongside live puppies at term or found on a scan. Or the dead fetus may remain and begin to break down in a way that seeds infection, which is the dangerous version, showing as foul discharge, fever, abdominal pain and a mother who becomes ill. Later loss can also trigger premature labor for the whole litter. Because the outcomes diverge so widely, any sign of later loss belongs to a vet, who will use ultrasound to check how many fetuses remain and whether they are alive, and will judge whether the mother needs treatment, monitoring or intervention.
Infection heads the list. AKC guidance names bacterial causes including Brucella canis, E. coli, Streptococcus, Leptospira, Campylobacter, Salmonella and Mycoplasma, and viral causes including canine herpesvirus and distemper. Merck material on brucellosis describes Brucella canis as a cause of abortion typically in the last trimester, often with no warning illness in the mother, followed by prolonged discharge, with stillbirths and failed conceptions also part of the pattern. It spreads readily between breeding dogs, is very difficult to cure, and can infect people, which is why it is tested for before breeding and investigated after losses. Hormonal failure is the second major group: progesterone maintains canine pregnancy from start to finish, so a mother who produces too little, or whose uterus stops responding to it, cannot hold a litter. Problems in the mother, including thyroid disease, kidney or liver disease, diabetes, autoimmune conditions and uterine infection, can all end a pregnancy. Problems in the fetus, especially developmental and genetic abnormalities, explain many early resorptions. Outside causes complete the list: trauma, extreme stress, serious nutritional deficiency, and exposure to certain drugs or toxins, which is why every medication in pregnancy should be cleared with your vet first.
Expect history first: mating and test dates, diet, vaccinations, medications, previous litters and losses, and the signs you saw and when. Examination follows, with ultrasound as the central tool to establish whether fetuses remain and whether heartbeats are present. Where infection is possible, the vet may test blood, culture vaginal discharge, and examine any expelled fetus or tissue under the microscope, because finding the cause changes what happens next for this dog and for any other breeding dogs in the household. Treatment depends entirely on findings: a mother resorbing early with no illness may need only monitoring; a mother with infection, a retained dead fetus or systemic illness may need antibiotics, hospital care or surgery. There is no home treatment for miscarriage, and no supplement that holds a failing pregnancy. What owners can do is arrive fast, bring dates and any tissue in a clean container using gloves, and keep other dogs, especially breeding dogs, away from discharge and material until the vet advises.
Grief after losing a litter is real, and practical decisions still need care. Do not re mate her on the next heat by default. The sequence is recovery first, cause second, decision third: let her body and condition fully recover, complete any testing the vet recommends, which for brucellosis may involve repeat tests over time, and only then discuss whether breeding again is sensible, with what timing and what monitoring, such as progesterone checks or extra scans. A dog who has had brucellosis should not be bred again, and infected dogs need isolation advice from your vet because of the risk to other dogs and to people. A dog whose loss was a one off fetal abnormality, with a clean work up, often goes on to carry a normal litter. Keep records of everything; patterns across litters are diagnostic information no single event can provide. Our guide on when to breed a dog covers the preparation that gives any future litter its best start.
Related: dog pregnancy tests, signs of dog pregnancy and false pregnancy. Back to the breeding hub.
The loss of one or more fetuses during pregnancy. Early losses are often resorbed by the body with no outward sign. Later losses may be expelled, may remain and become mummified, or may be delivered alongside live puppies at term.
Later losses may cause abnormal discharge that is bloody, green, black, brown or pus like, abdominal pain or cramping, fever, lethargy, early labor behaviour or expelled tissue. Early resorption usually has no signs at all and is only found when a later scan shows a smaller litter or no pregnancy.
Causes include infections such as Brucella canis, canine herpesvirus and several common bacteria, low progesterone, fetal abnormalities, illness in the mother such as thyroid, kidney or diabetes problems, trauma, severe stress, nutritional problems and some drugs or toxins. Many cases are never explained.
Yes. One or more puppies can be resorbed or lost while the rest continue normally and are born healthy. The only evidence may be a smaller litter than an early ultrasound suggested.
Call your vet the same day, immediately if there is discharge, pain, fever or illness. Keep any expelled tissue in a clean container for the vet if you can do so safely, note dates and signs, and do not handle material with bare hands because some causes, including brucellosis, can infect people.
Often yes, but only after a veterinary work up and a clear plan. Infectious causes, especially brucellosis, change the answer entirely and can rule out future breeding. Never simply re mate on the next heat after a loss.
This page is general information drawn from the published guidance of the organizations listed under Sources below. It is not veterinary advice, and it does not replace your own veterinarian, who knows your dog. Pregnancy and birth carry real risks for the mother dog and her puppies. If you are worried about a pregnant, whelping or nursing dog, contact your veterinarian or an emergency clinic straight away. For a poisoning emergency, the ASPCA Animal Poison Control Center is on (888) 426-4435 and the Pet Poison Helpline on (855) 764-7661. A consultation fee may apply on the helplines.
Last updated: November 2026. Facts on this page were checked against the sources listed above. How we work: our methodology.