Uterine atony, also called uterine inertia is a pregnancy condition where uterine contractions needed for a normal whelping wimp out, leaving babies inside mama that require medical help if they are to survive.
This girl carried seven growing puppies her womb.
During their two month gestation period each pup develops inside its own vesicle, called the amniotic sac.
The developing embryos float in the fluid like sea otters tethered to a mother ship by the umbilicus, the umbilical cord.
This cord is the developing pup's link to survival; it brings oxygen to the fetus from the placenta, and plays a crucial role in the growing embryo's survival environment by transferring nutrients and oxygen from the lining of to the growing baby.
During birth the placenta pulls free of the uterine blood supply. It is no longer useful, and becomes the afterbirth. Now the puppy must make it outside in order to take its first breath.
The puppy has to make it outside the uterus before it is freed from the amniotic sac and its nose cleared. Only then can the newborn begin to breathe.
If the delivery process is stopped and the birth is delayed too much after the placenta separates from the uterine lining the puppy will die of lack of oxygen.
As outlined above, there comes a certain point in the birthing process where the placenta detaches from the uterine lining, cutting off maternal oxygen supply. This is when the puppy begins a race for survival; it must make it outside mama before it will be able to open its mouth, and take a breath.
But the pup needs help from mom. She is the one who must push the newborn into the outside world. Her uterus must contract rhythmically and repetitively to expel a baby correctly. She relies on a muscle push called the Ferguson Reflex to accomplish this task.
The Ferguson Reflex was coined to explain the usual procedure in normal birthing. When ready to be born a puppy squirms against the inside of the mama's cervix causing the repetitive explosive sudden release of the oxytocin birth hormone. This causes the entire uterus to contract in a front to back manner similar to squeezing toothpaste from a tube aiding delivery, of the baby. The density of Oxytocin receptors increases as much as 200-fold as parturition approaches, which markedly increases the sensitivity of the uterus to the hormone
Usually this sequence of hormonal changes continues unimpeded until there are no puppies remaining inside the uterus, when the Ferguson Reflex shuts down. Uterine atony occurs when this sequence stops too soon. Any baby still waiting for expulsion will die unless assisted. Because the placenta has detached it needs to breathe outside air within the next half hour, otherwise the baby suffocates before it is born.
We know Alan's ten pups were developing nicely from the latest ultrasound. Their heartbeats looked like flashing lights. When the bitch began to deliver, four pups came out. Then there was a long delay, too long. The placental-uterine separation had finished, but the last six pups didn't make it out in time.
I recommend these bitches be spayed. Their next birthing process will likely be fraught with similar heartbreaking disappointment. However, some people feel they really want this bitch to have another litter, and there is a way this can be done safely if end-stage heartbeat monitoring and a standby surgeon are available to begin an immediate c-section.
Above is a heart beat monitor which can be ordered or leased from an online service. You need to begin monitoring the puppies' heart rates a week before the due date. Normal fetal HRs for dogs are greater than 200 bpm (beats per minute) Fetal distress is indicated at 170 and is severe at 150
Get used to what your pups heart rates are before this so you know when and how fast the beats are dropping. That's when you call for a c-section.
Realize there is also danger in calling for a c-section too soon. The pups will be premature and will die within a half hour of the surgery, so this can be a risky undertaking if you fail to understand the warning signs.
You Tube video of monitoring fetal heart rates: