The Birthing Process


Understanding the normal mechanisms of whelping, or parturition, can help you weigh your options and determine whether veterinary intevention is necessary and at what stage you should intervene. Each bitch is different and you will need to know and understand your bitch to be able to detect early warning signs that all is not as it should be.


Initiation of Birth:

Initiation of birth is stimulated by the puppies and not a response by the dam. As the fetuses grow, they receive less nutrition from the placenta. This causes stress-related hormones (adrenocorticosteroid or cortisol) to be released from each puppy's brain. These hormones in turn cause the placenta to release prostaglandin, a chemical that initiates the destruction of the corpus luteum or "yellow body" on the ovary that forms after eggs are ovulated. The corpus luteum plays an important role throughout a dog's pregnancy by secreting progesterone, the hormone that maintains the pregnancy. Destruction of the corpus luteum results in a sharp drop of progesterone levels one to two days before whelping, slowing the metabolic rate in the bitch and triggering the decline in temperature we see prior to whelping.

Without the inhibiting effect of progesterone, the uterus can contract and the cervix can open for birth. Cervical dilation and uterine contractions themselves are primarily caused by the secretion of oxytocin from the brain stem, or pituitary gland, of the bitch. The injectable form of oxytocin is known to many breeders as the "pit" shot. Early labor contractions allow a puppy to enter the pelvic canal of the bitch, which triggers the release of oxytocin by the dam and more strenuous contractions. This process of stimulation by the pup, which is necessary for its own birth, is called the Ferguson's reflex.


Stages of Labour:

The natural progression of labor is broken down into three stages:

• Stage 1: is preparation for actual labor. It includes nesting, vomiting, panting, shivering and a temperature drop of 1 to 2 degrees to less than 99 degrees F. Stage 1 usually lasts 6 to 12 hours, but can range between 0 and 48 hours.
  
  
• Stage 2: is active labor. The fetal membranes rupture (often called the "water breaking") and the first fetus enters the pelvic canal, triggering Ferguson's reflex and strong labor contractions. Normally the birth of a puppy should be seen within one to two hours of these strong contractions. The bitch may then rest several hours between pups.
  
  
• Stage 3: is delivery of the placenta or fetal membranes. This usually occurs within 45 minutes after the birth of each pup.

Disturbance of this natural progression results in a diffiIt birth or dystocia. Dystocias are usually classified as to whether they are due to inadequacies of the bitch or to complications with the puppies. Birthing problems that primarily involve the bitch include:

~ Physical abnormalities of the birth canal. This includes problems such as a malformed vagina or an old pelvic fracture.

~ Primary uterine inertia or failure to go into Stage 2 labour. In these animals, separation of the placenta from the terus occurs, but no puppies are delivered. A greenish black vaginal discharge is observed before the birth of any puppies. The puppies inside the uterus will die without surgical intervention.

~ Secondary uterine inertia or exhaustion of the uterine muscles. These animals stop labor during Stage 2 and require assistance to continue.


Problems due to the puppies include:

• A pup that is too large.
• Improper positioning of the puppy in the birth canal.
• Dead puppies, which fail to trigger whelping because there is no increase in cortisol.

Combinations of problems due to the dam and the pups also occur. For example, a bitch with only one or two pups may not be able to trigger whelping in a normal manner, resulting in primary uterine inertia. Small litters can also grow too big in the uterus and may cause a fetal oversize dystocia.




CALL THE VETERINARIAN WHEN


1) There is any abnormal vaginal discharge including:

• green / black discharge with no sign of straining before a pup is born
• constant dripping of pure blood
• foul smelling pus

2) The bitch has a prolonged gestation, especially if no fetal movement can be seen.


3) Signs of toxemia are developing in the bitch including:

• fever
• depression
• weakness
• rigid gait or seizures

4) There are signs of an obstruction, including:

• severe pain or crying out during contractions
• visualization of a pup and/or its membranes which cannot be delivered by careful assistance

5) No progress has been made towards the delivery of a pup after:

• initial labor over 3 hours
• hard straining over 30 minutes between pups
• weak intermittent labor of over 2 hours between pups
• no labor over 4 hours between pups

Determining whether or not you have a dystocia, and whether or not it is time to intervene, is rarely a clear-cut decision. Aside from the exceptions listed when veterinary assistance should always be sought, how you decide to proceed will be based in part on the value of the litter and the bitch to you. Some breeders are comfortable monitoring the dystocia themselves, realizing their "wait and see" attitude may result in the loss of a pup or two. However, if this is the first and only litter of an 8-year-old bitch whose pregnancy cost you $350 in progesterone tests and vaginal cytology smears, you probably won't want to risk losing any puppies, and will rather err on the side of early intervention.

In addition to the emergency situations described a dystocia should be suspected if:

• one to two hours have passed after beginning Stage 2 labor without a puppy
• more than three hours of rest have occurred between puppies
• if the bitch has been in hard labor for 30 minutes with no progression toward birthing a pup.

If you only bave breeding dates to go on and you are considering an elective C-section, progesterone testing can help confirm the bitch is truly term before the pups are delivered. Progesterone levels less than 2 ng/ml are seen in the full term bitch. If progesterone has not dropped, the pups may not be ready to thrive outside of the uterus. Ultrasound can be used to make sure the pups are not distressed in the uterus while you wait for the bitch's progesterone to drop.


IS MY BITCH OVERDUE ?

Normal deliveries should occur:

• 57 to 72 days after a first breeding
• 65 +/- 1 days after luteinizing hormone peak, based on blood progesterone levels at heat
• - 57 +/- 3 days after the first day of diestrus based on vaginal cytology at heat

Knowing approximate litter size as determined by ultrasound examination or radiographs can also be helpful. If a bitch stops contracting after two pups, but you saw eight on the ultrasound, you will need to seek help for a possible secondary uterine inertia. This is also important in older bitches and those breeds that tend to whelp small litters. These animals will be prone to having both oversized pups and primary uterine inertia. Knowing you have a small litter beforehand allows you to be more watchful rather than being caught off guard by a possible dystocia.

Diet and exercise are critical. Keep your bitch physically fit by moderate exercise during pregnancy. This helps her have good muscle tone to push during the whelping. Also, avoid diets high in calcium before whelping. This is especially important in Toy breeds, and in bitches with large litters, where eclampsia or low calcium is a problem after whelping. Eclampsia can cause seizures and death of the bitch if not dealt with immediately. There is good evidence in cattle, which have been studied extensively for this problem, that feeding high levels of calcium before calving actually makes the female prone to suffering from low calcium while nursing. Save the high-calcium diet and supplements for after whelping when the bitch is actually nursing the pups.

Diets too low in carbohydrates can lead to low birth weights and death of pups during delivery. This is most commonly seen in bitches with several pups, who are unwilling to eat during the last part of pregnancy because of discomfort. Offer these bitches small frequent feedings of soft foods; however, stay away from high fat foods which may cause pancreatitis.

Finally, be sure to have a complete breeding soundness examination performed by a reproductive specialist on any bitch you plan to keep for breeding. This exam will detect anatomical defects such as a persistent hymen in the vaginal vault that may interfere with whelping, and the presence of low-grade infections in the vagina that could lead to complications. Click here for extra reading on Whelping A Litter