January 5, 2016
Have you ever wondered about the similarities between pregnancies for dogs versus people? If you were to ask a dog, you might be surprised. Molly was a Miniature Schnauzer, black and silver, who had undergone a planned breeding. Following the textbook, Molly was bred on Days 9 and 11 after showing the first signs of her heat, or estrus cycle. She “took”. Early on Molly cried when she tried to jump onto the couch. Only 3 weeks into a measly 63 day gestation (compared to a woman’s 40 week gestation), we were pretty sure she felt tugging in her tummy as her uterine ligaments stretched to support the expanding womb. Her owner made a step-up to the couch for her. She was switched to a high protein, calcium-rich puppy food during the pregnancy and would continue this food through her lactation. Her girlish figure didn’t change much during the first 5 weeks when, kaboom, she blossomed out with a full tummy (anyone relating here?). Although her appetite had been ravenous after the intial weeks, in late pregnancy Molly began to eat small meals as the pressure from her pregnancy compressed her stomach and diaphragm. She waddled. She was easily winded, no more chasing butterflies. Treats sounded fantastic and had to be closely rationed.
One of the interesting things about dogs is the shape of their bicornuate uterus, which has a tiny uterine body but very long “horns”, tube-like structures along which multiple fetal puppies can attach and grow. As the uterine horns expand with the growing puppies, the support cradle of uterine ligaments must also stretch and a close outside observer may witness the primparous (first pregnancy) dog’s discomfort as she moves about. After day 45 of the pregnancy x-rays may be taken to ascertain the number of pups to expect, as the skeletons are well-calcified. On an x-ray the puppies look like little fish. We count only the skulls, as backbones and legs can appear tangled together (though in reality each puppy is safe inside its own placental sac). An ultrasound can also be performed to assess the number of puppies (ultrasound may be less accurate in determining fetal number) and check for fetal heartbeats. Knowing how many puppies to expect is very helpful when the time comes – for the mothers sake you want to be certain her labor is over and there are no retained, unborn puppies stuck inside. As the pregnancy progresses, it is fascinating to note that the puppies in one sense send out a signal to the Mom that they are ready to be born! Each puppy has its own placenta, the little birthing sac they grow inside. Puppy and placenta will secrete hormones to start the birthing process, relaxing the pelvic ligaments and assisting the body to open up for delivery. It has been suggested as hypothesis that singleton pups (only one inside) are more likely to need a Caesarean-section (a surgical delivery) because one puppy placenta may not make enough hormones to set things in motion. The hormone oxytocin facilitates actual contractions, and may be given by injection if your veterinarian needs to assist the labor process. An oxytocin intravenous drip, as used in people, is not effective in dogs.
Molly tried to make a nest in her owner’s closet, carefully raiding the hamper for suitable soft clothes. Doubtless the scent of her owner was reassuring – nevertheless, they put her own bed in place and retrieved their things. Birthing is messy. As the time for the whelping (parturition) drew near, her owners found it valuable to take her temperature rectally twice a day. The body temperature drop is caused by the sudden drop in the hormone progesterone when birth is imminent. At home a dog’s temperature may normally run between 100 to 101 degrees. In many expectant dogs, the temperature will drop sharply within 24 hours of going into labor. If you see the thermometer registering 97 degrees, time to stay close!
One Thursday night Molly went into labor. She had skipped her breakfast and seemed to be distracted during the day. Finally, it was obvious that she started contractions. You could see her stomach scrunch up as they became harder! Molly huddled near her owner, panting furiously. She was a little surprised by the pain, scared. After about an hour, Molly delivered her first puppy with a short scream (it hurt), then turned to help open the placenta and lick her firstborns face. Had the dog pushed hard with no results for over an hour her owners would have brought her in to the veterinarian. The pup squealed with it’s first breath and Molly properly chewed through the umbilical cord. In 20 – 30 minute intervals, she delivered a litter of 5 healthy puppies. After a change of bedding, she rounded them all up and they began to nurse. A most successful outcome. Fourteen hours later, Molly’s owner delivered her own healthy baby. It was a busy house!
Christine McFadden, DVM
drmc@mcmenagaerie.com