The normal gestation period for female dogs is approximately 63 days. Depending on the breed, pregnancy can range from 56 to 69 days, with smaller dogs generally giving birth slightly earlier. The beginning of labor is usually marked by a drop in body temperature and sometimes lack of appetite in the pregnant bitch, or dam. This is followed by the first stage of labor, when the dam starts experiencing mild to moderate uterine contractions and the cervix starts to dilate. The contractions last up to 16 hours, and are marked by behavior changes, as well as sometimes vomiting, panting or vocal noises. Stage two labor starts when the contractions become more extreme, the placental sac breaks and the puppies begin to be pushed out. Stage three labor occurs after all the puppies have appeared and the uterus is emptied of any remaining placental matter. Most female dogs have straight forward pregnancies and give birth without incident, but a number of conditions including infectious diseases, hormone imbalances, genetic abnormalities and stress can cause a dam to go into labor early and either have a spontaneous abortion (a miscarriage) or give birth to premature puppies. In most cases the bitch will survive, although she may have trouble getting pregnant and/or whelping going forward. Puppies born more than a few days early have little chance of survival and may even be stillborn.

Almost 98% of dogs give birth without incident, but in a few cases, an infection or another abnormality may cause a dog to go into labor before the right time. This is defined as early contractions and labor (or 'premature labor')  by veterinarians. It can lead to miscarriage as well as stillborn or premature puppies, depending on what stage of gestation the bitch is in. Certain conditions may affect the female's fertility and ability to reproduce going forward.

If you think your dog is going into labor, you should contact your veterinarian, especially if it is more than a day or two before the expected time. Some common signs include:

We classify pregnancy loss according to the stage of gestation:

These are some of the most common conditions which might cause your dog to abort a pregnancy or to go into labor before the proper time:

Diagnosis of early labor will be based on the symptoms and the expected time of delivery. If you monitor your dog’s temperature regularly, you may notice a drop about 24 hours before she goes into labor. Otherwise, symptoms of contractions will be the first sign that there is a problem. Early labor may not follow the normal stages. 

Call your veterinarian as soon as you notice unusual symptoms in your dog. If she has already expelled puppies or fetal material, you should bring this to the veterinarian for testing if possible. Dogs often eat their stillborn offspring, so this may not be possible. The veterinarian will want to know your dog’s medical history, including the date the breeding took place and any prior births or pregnancies. Other medications, recent vaccinations, and possible exposures to toxins or infections are relevant. Any information you have about the puppies’ sire could also be helpful.

The veterinarian will perform a complete physical examination. Blood, urine, and vaginal cultures will be taken to check for infection or other abnormalities. Any expelled material will also be examined. It may be obvious upon feeling the dog’s stomach that there is still fetal material or puppies in the uterus. An abdominal ultrasound may be ordered to garner further information and to assess fetal heartbeats.

Sometimes a single unhealthy fetus may be aborted, while the others are carried to term normally. The veterinarian will try to determine the cause of the early contractions and labor, as well as whether your dog is fertile and capable of another successful pregnancy. Sometimes exploratory surgery could be necessary to check for abnormalities in the uterus.

Treatment will be based on the veterinarian’s findings during diagnosis. Any confirmed bacterial infection will be treated with antibiotics. Dams who are very sick will be given fluids and supportive treatment as necessary. Medication may be given to aid uterine evacuation if fetal membrane or dead fetal material remains in the uterus. If healthy fetuses remain, the veterinarian will attempt to stop the contractions and reduce the likelihood of these puppies being born prematurely. Your dog will likely need to remain in a veterinary hospital for several days for treatment and monitoring.

If premature puppies are born underdeveloped, but otherwise healthy, they will need to be kept in intensive care. Puppies born 5-7 days early have a reasonable chance of survival. Puppies born more than 8 days early will usually be unable to swallow or go to the bathroom without help. They will need 24 hour care and may still die. Puppies born more than 10 days early are very unlikely to survive. Errors in calculating the gestation period are not uncommon, so the puppies could be more or less developed than would be expected based on the date. 

Recovery will depend on what has specifically happened. A few dogs do die due to premature birth, but the majority will survive especially with prompt treatment (unless the early labor is due to a life-threatening condition.) Fertility may be affected , so you will need to discuss the possibility of your dog having another healthy birth. The veterinarian may recommend having your dog spayed to prevent future pregnancies.

Many conditions of early contraction and labor are preventable. Ensuring your bitch is up to date with her vaccinations and parasite prevention and is being fed a complete diet can go a long way. Getting your dog checked over before she is mated and when she first becomes pregnant is also a good idea. Similarly, only studs that have been health checked and certified clear of infection should be bred with. Maintaining good health in the dam is very important during pregnancy. Have regular check-ups  and avoid situations of overcrowding which will cause stress.