DVMs can help clients understand behaviors during, after delivery
Q I see a few novice pedigree dog breeders in my practice. Please provide a concise review about natural delivery of puppies and information that these novice breeders could benefit from reading.
A At the end of last year, I published a simple article on natural delivery of puppies and some of its associated problems - Hoskins JD: Whelping and care of newborn puppies. Pedigree Breeder Forum 9(3):7-13, 2000. Some of the information in this column is presented in that article for client reference.
As natural delivery of the puppies approaches, bitches may change their eating habits. Some bitches will eat more than a normal amount of food and constantly beg for more; others will reduce the amount they eat or eat very little.
At least 24 hours before natural delivery of the puppies, it is a good idea to clip short the long hairs surrounding the nipples and the vulva to prevent interference with delivery and nursing. Approximately 18 to 24 hours before natural delivery, the bitch's rectal temperature should drop 1F to 2F below the normal rectal temperature. The normal rectal temperature for adult dogs at home is 100F to 101.8F. Rectal temperature can be taken twice a day. When the rectal temperature drops, it is important to stay close because delivery is near.
Natural delivery has three stages. Stage 1 begins with contractions of the uterus and ends when the cervix is fully dilated. It takes about six to 12 hours.
Bitches may appear restless and nervous and may shiver, pant, vomit or pace. Most bitches seek a place to "nest" near the end of this stage. Stage 2 begins with full dilation of the cervix, entry of the first puppy into the birth canal, and rupture of the membranes that surround the puppy. Stage 2 ends with delivery of the last puppy. The bitch shows obvious intense abdominal contractions in her attempt to deliver the puppies.
The time between initiation of stage 2 and delivery of the first puppy varies (it is usually less than four hours). The time between deliveries of subsequent puppies also varies (usually 20 to 60 minutes), but can be as long as two to three hours. Stage 3 begins after delivery of the puppies and ends with passage of all membranes. If the bitch has multiple puppies, she may alternate between stage 2 and stage 3.
Difficulty in natural delivery
The natural delivery problems of puppies usually involve a small or deformed birth canal, an oversized puppy or weakness of the uterus (that is, insufficient force of the uterus to propel a puppy through the birth canal).
Natural delivery problems are present if the bitch has had 30 minutes of persistent, strong, abdominal contractions without expulsion of a puppy.
Other problems include:
- If more than four hours have passed since the onset of stage 2 to delivery of the first puppy;
- If more than 2 hours have passed between delivery of puppies;
- If the bitch fails to deliver a puppy within 24 hours after rectal temperature falls below 99°F or within 36 hours of serum progesterone being <2 ng/ml.
A natural delivery problem also exists if the bitch cries and displays signs of pain and constantly licks her genitals when trying to deliver. The normal length of pregnancy is 63 days from the last breeding. Natural delivery problems exist if the pregnancy is prolonged (that is, more than 70 days from day of first mating, more than 59 days from the first day of diestrus (the time when the bitch will not allow the breeding act to occur), or more than 66 days from the peak in the serum luteinizing hormone (LH).
Assisted natural delivery
Assisted natural delivery is used when a puppy is lodged in the birth canal during delivery. Preferably, a veterinarian should be used for assisted natural delivery.
The veterinarian will apply lubrication liberally on a gloved hand and place the bitch in standing position. Use of gloved fingers is the safest and most reliable approach to manually pulling a puppy through the birth canal.
If the birth canal is too small for fingers to move and lubrication is adequate, the veterinarian can use instruments.
Breeders should never use instruments in attempting assisted natural delivery of live puppies. These instruments can do great harm to the puppy and to the bitch.
The veterinarian will place a gloved finger in the birth canal to direct the instrument. A spay hook or a non-ratcheted forceps is used, and traction should be applied to deliver the puppy in a posterior and ventral direction. Traction on a single leg is definitely contraindicated. The veterinarian will perform a cesarean section if the puppy cannot be delivered within 25 to 30 minutes.
Two types of cesarean sections are generally performed in dogs: unplanned and planned. An unplanned c-section is necessary in the bitch with the following: weak contractions of the uterus, unresponsiveness to the hormone injection oxytocin to stimulate contractions of the uterus, pelvic or vaginal obstruction, a puppy in an uncorrectable position, oversized puppies, puppy stress or a dead puppy still in the uterus. Planned c-section is necessary for breeds highly prone to failure of natural delivery and bitches with a history of failures in natural delivery.
Establishing immediate maternal behavior
Establishing maternal behavior of a birthing bitch involves a variety of hormones, experience as a birthing bitch, hereditary tendencies and the stimulus provided by the newborn puppies.
Vaginal-cervical stimulation, which is caused by the passage of the puppy through the birth canal, causes oxytocin release by way of spinal afferents with neural connections to the hypothalamus. The cells that produce oxytocin are located in the hypothalamus.
These cells have axons that carry the hormone either to the posterior pituitary gland, where it is released into the peripheral blood stream, or to other parts of the brain, including the olfactory bulb. In the olfactory bulb, oxytocin stimulates the release of monoamines and opiates, which then initiates a sensitive period during which the bitch will identify the smell of the puppies as her own. The period during which a bitch will form a bond with a specific puppy is probably less than 24 hours.
Apparently, a decline in circulating estrogen and prolactin, an increase in oxytocin (and possibly prolactin), cervical stimulation and the presence of a small puppy with a foreshortened face and wet with amniotic fluid are all factors involved in establishing the bitch's maternal behavior.
Problem: Puppy rejection is an immediate problem with some birthing bitches. Immediate puppy rejection usually occurs in primiparous bitches. Experience with being a nursing mother once seems to be very important. Multiple rejection episodes are uncommon, possibly because owners do not breed the bitch again after she refused to nurse her puppies the first time. Solution: Sometimes characteristics of a newborn puppy can be used to induce a new mother to accept her puppy if she is not naturally maternal or to motivate a bitch to accept a puppy that is not her own.
These characteristics are that it is small, uncoordinated, and wet. Wetting with amniotic fluid is the best way, but amniotic fluid is usually not available. Wetting the puppy with warm water can be effective. Be sure that the puppy does not become chilled as a result. The bitch will lick the puppy, thus drying it and possibly triggering the natural maternal acceptance.
Problem: C-section is frequently associated with immediate rejection of newborn puppies. Case example: Immediately following surgery, the puppies are introduced to the bitch in her cage in the hospital's observation and recovery area. She immediately kills a puppy. The owners then take the puppies and handle them before representing them to the bitch in their van. Apparently, the combination of a more familiar place as in their van and the owner's scent on the puppies was enough to inhibit aggression and allow the bitch to recognize the puppies as her own.
Solution: It is important when introducing the bitch that has had a recent cesarean section performed to her holding cage in the hospital's observation and recovery area that the holding cage be warm and as free of noise as possible. The newborn puppies should already be in the holding cage and making sounds that indicate hunger.
It is also extremely important to allow sufficient time to pass for the bitch to establish her maternal behavior before she is transported to the home or a new location. Birthing in familiar environments always helps to reduce aggression toward newborn puppies.
Problem: Occasionally, puppy rejection can lead to cannibalism. In some cases, the bitch eats the placenta and chews the umbilical cord and she may keep on chewing up the umbilical cord and begin consuming the puppy. Solution: There is nothing one can do to stop cannibalism of a litter of puppies once it starts other then to raise the newborn puppies as orphans.