The last 3 weeks of pregnancy and the first 8 weeks of life are the most vulnerable time for a puppy, but particularly immediately before and after birth. Regardless of how many puppies were born, it is the number of puppies weaned that determine how successful that breeding will be.

In an ideal world, the dam would be a healthy, mature dog, which has been maintained well with regular vaccinations, dewormings and heartworm prevention. She would be in optimal body condition prior to breeding and throughout her pregnancy. She would have had optimal nutrition throughout her puppy hood and adult life prior to breeding. The bitch would maintain a full term pregnancy, and have a natural whelping, free from complications.

Ideally, the litter would be an average, to just over average, number of pups, with the pups being within close normal range of body weight. The pups would all be fully developed, and able to root and suckle soon after birth. The dam would be attentive to the pups. The pups would nurse as soon as possible and frequently through the first 24 hours and ingest colostrum rich in antibodies. The pups would be able to pile together in sleep to help conserve body heat. It would be expected that the pups would double their birth weight by 10 days of age.

Many times, that’s exactly how the breeding, birth and nursery of a litter of pups go. But not always.

What happens when the pups that are successfully weaned are not the full number of pups born?

There are three times of particular concern here, the last three weeks of gestation, birth, and the first days and weeks of life. Some threats to the puppies’ survival are potential at all three of these stages, while other threats are greatest at a particular point.

Infectious agents are one of the threats that can impact survivability at each of these times, though the level of threat may vary. For instance, canine herpes virus can trigger abortion and stillbirths if the dam is exposed late in pregnancy. If the pups are exposed to the virus during birthing, they will likely die within 3 to 4 days. The impact of canine herpes virus is generally much less when the animal is exposed outside of the critical time periods for pregnancy and neonates.

There are two canine parvovirus types that cause disease in dogs. The one most commonly known is parvovirus type 2, causing the hemorrhagic gastroenteritis with the metallic smelling diarrhea, that is so strongly associated with "Parvo". Canine parvovirus type 1, also known as the minute virus, can cause abortion and stil births, as well as enteric disease in neonates. The challenge with type 1 is that it can be very difficult to diagnose, and there is no effective vaccine. It is estimated to have a prevalence of approximately 50% throughout the United States. The only defense is a good offense through sound biosecurity.

Bacterial agents can be pathogenic and manifest through fetal death, stillbirths, and early neonatal death. Brucella canis, not surprisingly, is one of the most common offenders. It is very much an active threat to every dog breeding facility, and prevention demands consistent testing of all breeding animals, with special emphasis on new dogs, or dogs that have been out of the kennel for breeding, and are returning. One must pay attention to the time at which the dogs are tested, as it does take some time for the dog to show a positive response to the test after exposure. So you don’t breed the dog until you have a reliable negative test.

Other bacterial agents that can cause puppy loss, before and after birth include campylobacter spp., E.coli, beta-hemolytic strep, and mycoplasma.

Here again, the best prevention is a solid biosecurity strategy that is consistently applied.

As far as parasites, both toxoplasma gondii, and neospora caninum can cause loss of fetal life with abortion or stillbirths. Roundworms and hookworms are generally not acknowledged as aggressive threats to survivability of puppies, but heavy infestations can significantly weaken neonates and render them more vulnerable to secondary threats, and metabolic problems from enteric disease. The same can be said for coccidia and Giardia.

The occurrence and prevalence of congenital defects certainly can complicate survivability issues. It is widely recognized that purebred dogs have higher prevalence to congenital defects. As breeding stock becomes more genetically concentrated, with a higher degree of inbreeding, there is more opportunity for recessive genetic traits to be exhibited. There is also a greater chance of deleterious mutations to the genetic material in purebreds. Along with genetics is the basic body conformation involved and increased risk of dystocia in some breeds. Some defects that are relatively common are cleft palates and other mouth abnormalities, developmental problems with the intestinal tract and anal orifice, and persistent embryonic heart structures, or malformations.

The length of the pregnancy can be a determining factor in the survivability of the neonates. It is normal for large litters to have slightly shorter pregnancies. Likewise, small or singleton litters may have slightly longer gestations. If there is a problem with ovarian tissue (follicular cells that evolve into luteal cells) maintaining active secretion of progesterone, the pregnancy can terminate prematurely. Sometimes the presence of infectious agents will shorten a normal gestation. Outside of the slightly shorter gestation due to large litters, survivability is greatly affected negatively by shortened pregnancy.

As mentioned earlier, litter size can influence other factors in the pregnancy from gestation length to survivability of the neonates. Large litters have higher number of pups born dead, and higher neonatal death losses. Typically, those pups born in a large litter will have smaller birth weights. Conversely, very small litters can experience more frequent dystocia issues from the pups growing too large and causing obstruction problems.

While large litters influence the success of that current pregnancy, they can also exert an effect on the subsequent pregnancy as well. Large litters drain the dam of body reserves as she struggles to provide all the necessary nutrients to the pups. If the bitch is bred again on the next estrous cycle, her body may not have restored all those nutrient reserves. What the female eats between pregnancies is equally important to her breeding performance as what she eats during pregnancy and lactation.

Not surprisingly, the time it takes a bitch to deliver her pups directly influences survivability. When events are put into effect and the whelping process has started, already the uterus is preparing for the separation of placenta. If there are several pups gradually being squeezed down the lengths of the uterine horns, there may be too much separation to maintain oxygen levels and the fetus/neonate suffocates. Of course, once a pup dies within the uterus, the breakdown of tissues and blood components can cause problems for the adjacent pups and placentas. Generally speaking, a normal delivery should complete within 12 hours.

One of the greatest predictors of survivability is the birth weight. Each breed has its own normal range of birth weights, which tend to run very similar to other breeds within its size classification (toy, small, mid-size, large and giant breeds). This range can exist due to size differences within the breed, litter size, length of gestation and environmental conditions. Puppies that are only 75% of average weight, or lower, have a higher risk of suffering hypothermia, hypoglycemia bacterial infection and pneumonia. Breeders need to record the birth weight of each pup as soon as possible. Not only does this identify those neonates that may need closer watching, but it can help establish a normal range for that breeding operation. As well, with that baseline value, the breeder can monitor growth rate with daily weighing. The very first indication that something is wrong, regardless of the nature of the problem, or the cause, is often decreased, or stalled, weight gain. When a lower than expected weight gain is found, alarms should be ringing, because something is going on and that pup is at risk. Corrective or supportive actions can be implemented and many times, the disaster averted. It is best to use a gram scale as it is much more sensitive and accurate than an ounce scale. Considering there are just over 28 grams per ounce, it’s easy to appreciate that greater accuracy is provided with grams. With the toy and small breed puppies especially, this difference can be critical.

Another factor in survivability of neonates is the colostrum they get. The ingestion of colostrum provides maternal antibodies which provide passive protection in the newborn. It is considered passive because the pup’s own body did not make the antibodies in response to a pathogenic challenge.

However, not all colostrum is created equal. Obviously, the dam’s immune status will dictate the levels of antibodies she secretes in colostrum. This is one of the strongest reasons to keep the breeding females on a regular vaccination protocol, between breedings. Another consideration is the period of time the newborn pups have to suckle immediately after birth. Their intestinal tract can only absorb intact immunoglobulins (antibodies) during the first 24 hours at best. The sooner they can start to feed, the better will be the benefit. Likewise, the amount of colostrum ingested through multiple feedings will impact absorption of adequate levels of passive immunity.

There are three big threats to the lives of neonates after birth. They are hypothermia, dehydration and hypoglycemia. Any of the three can trigger the other two conditions as if a domino pattern is in place.

The neonate is dependent on its littermates, its mother’s attention, and on the ambient temperature of its environment to maintain body heat. Newborns have relatively large body surface areas without insulating fat, which leads to rapid heat loss. During the first week of life the newborn’s body temperature should range between 96° and 98° F. They don’t have the ability to shiver yet, which normally stimulates heat production. The blood vessels in the skin and underlying layers are not capable of constricting to slow down heat loss. By week two, their body temperature is usually about 99°. It isn’t until week 4 that the pup is able to fully stabilize its body temperature.

The surrounding area temperature is vital to the ability of the pups to maintain body heat those first weeks. The recommended ambient temperature during the first week is between 85 - 90° F. Weeks two through four, 80° F is usually adequate. By week 5, it is safe to lower that ambient temperature to 70° F. It is evident that the newborn is dependent on ambient temperature to help maintain a healthy body temperature.

An important feature in a hypothermic pup is that they are incapable of digesting food at lower body temps and won’t attempt to nurse. If they are fed, or force fed while hypothermic, there is a good chance of aspiration pneumonia. Never attempt to feed a cold pup until it has returned to normal body temperature.

Conversely, a puppy whose body temperature is over 100° F is hyperthermic. This is as damaging as low body temperature. Newborn temperatures should be monitored as it is possible to over heat. Overheated neonates often cry constantly.

Toy breed pups are particularly vulnerable to low blood sugar, or hypoglycemia. Frequent feedings can help prevent this from occurring, but the risk and intermittent occurrence can extend for weeks to months. When the pup goes to the new home, they are especially prone to hypoglycemia, so it is vitally important that the new owners rigidly follow feeding guidelines.

Since newborn pups have little body fat, and no real capacity to make glucose from precursors metabolically, frequent nursing is vital. Even short time fasting can trigger a hypoglycemic state. If the puppy has not become hypothermic and still has a swallow reflex, oral fluid and glucose administration can often times replace the blood glucose allowing the pup to begin nursing again.

Dehydration can happen very quickly. Puppies are approximately 75 – 82 % water, with skin that is not capable of minimizing loss of hydration, and kidneys that cannot yet concentrate urine. The pups also lose water through the lungs with normal breathing. Water turnover in a newborn is two to three times that of an adult animal. They need to nurse frequently to replenish this water balance.

We are all familiar with pinching the skin on a dog to assess hydrations status. This tool does not work on neonates. Instead, checking the dryness of the mouth membranes and the inner eyelids are more reliable. Getting the specific gravity of the urine (done at the vet’s office) is the best way to evaluate hydration status.

The daily weighing of neonates are the best indication that mom may not be producing enough milk. Large litters’ demand for sustenance may outdistance the dam’s ability to provide milk. If inflammation has started in any of the mammary glands, it can decrease the volume of milk produced. Likewise, infection or inflammation of the uterus will have a negative chemical feed-back effect and reduce milk production. Mom is going to need constant availability of clean water in order to continue to produce enough milk. She also needs to eat a diet that is nutrient dense and palatable and in quantities that are always available.

Normal preweaning losses can range from 10 to 30%, with the majority of those losses occurring from stillbirths and death within the first few days. Good record keeping will help the breeder establish what is normal for her or his own kennel. If neonatal deaths become in excess of 25 to 30%, there is a problem and it needs to be investigated. Without dedicated recordings of stillbirths, and puppy losses at each week, the owner has no real appreciation for what is average, or normal, for their facility. Likewise, expecting to wean every puppy born is unrealistic. Not every lost puppy signifies a substantial problem.