The excitement grows as the queen’s belly expands. Normal pregnancy in cats averages 65 days. Larger litters tend to have a bit shorter gestations, while extremes can be from 54 to 74 days.
As the kittens grow in the uterus, fetal cortisol increases to a threshold which triggers a cascade of events including a decrease in progesterone. The decrease in progesterone to a median of 3.18 ng/ml, leads to the stimulation of myometrial contractions, the beginning of labor.
Stage one of labor is the longest stage where the cervix dilates and contractions begin. At this time, the contractions are generally not visible to an observer. A queen in this stage of parturition may display panting, nesting behavior and restlessness. She may also be anorexic and/or nauseous. The first stage may be as short as a few hours or as long as a day.
Stage two begins when active contractions are noticeable. Once these contractions begin, the first kitten should be delivered within four hours, but is usually closer to one hour. Stages two and three occur at the same time since kittens and placenta are expelled at the same time or relatively close together.
The interval between delivery of kittens may vary. Birth of a kitten may take only a few minutes. Kittens can be expected every thirty to sixty minutes, but may come much faster. If a queen is in active labor for more than two hours and no kitten is produced, veterinary intervention may be needed.
In some cases, queens appear to take a break from delivery, nurse kittens and rest comfortably. Labor then resumes with visible contractions. In some cases, parturition may last as long as two days when the female pauses. Queens should always be observed during labor, but kept in a quiet and stress free environment to help prevent interruption.
One third of kittens are born breech, while the other two thirds are born head and front feet first. Both presentations are normal. Most kittens are born in the amniotic sac. Knowledgeable queens will bite the sac as well as the umbilical cord and energetically lick the newborn to stimulate respiration. Inexperienced mothers may need assistance with this procedure. Some queens will eat the placenta when it is expelled.
If a cat needs assistance after delivery, the observer must intervene, by breaking the amniotic sac, cleaning fluid out of the mouth and vigorously dry the kitten to encourage breathing. The umbilical cord may be clamped and ligated about an inch from the kitten.
Dystocia, or difficult birthing, may occur in 3-6% of queens. This condition may be difficult to determine in a cat when the interval between kittens varies dramatically. Ideally, fetal heart rate can be monitored to detect problems. Less than 160 beats per minute in a fetus is an indication of severe stress. Some reproductive veterinarians prefer to see feline fetal heart rates stay at 200 or above.
The most common reason dystocia takes place is primary uterine inertia. Primary inertia may have a hereditary component or be due to hypocalcemia. Secondary uterine inertia is usually due to an obstruction by a kitten that is too large to pass through the birth canal or is not in the proper position to pass, such as when the head is turned sideways.
If assistance is required to pass a kitten whose head and front legs or rear legs and tail are visible, a rubber catheter may be used to infuse sterile lubricant in to the birth canal around the kitten. The lubricant may be sufficient to help the kitten pass. Manual manipulation of a kitten may lead to significant injury.
According to Dr Susan Little, there are times when veterinary intervention should be considered. A queen crying and biting at her vulva is clear indication of distress. In addition, a kitten or membranes visible at the vulva with no advancement for more than fifteen minutes, means veterinary care is indicated. Professional services should be sought if no kitten is produced within sixty minutes of strong contractions or if labor is not completed within thirty-six hours.
Oxytocin should not be used until after a radiograph shows that the kitten is of normal size and presentation. If this is the case, up to three doses of oxytocin may be administered approximately thirty minutes apart. In these cases, intravenous calcium is also likely to be needed. If no progress is made, a Caesarian section must be considered.
While only a small percentage of queens have difficulty having their kittens, it is vital that a birthing queen have an alert observer during the process. Being prepared to assist or seek professional help can save both kittens and queen.