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The Tres Amigos: Calcium, oxytocin, and glucose

Updated: Feb 29, 2020

Common sense disclaimer: As with everything else on this blog, it’s critical to seek the advice of a qualified veterinarian, preferably one that is board certified in theriogenology (reproductive science) for reproductive matters. This website, its blog, and its courses are NOT designed nor intended to replace the need for a qualified veterinarian, but instead to help educate people to to work optimally with their veterinarians. All recommendations should be reviewed with qualified professionals, such as a board certified reproductive veterinarian, prior to implementation in a breeding program. Always seek the advice of your veterinarian. Readers assume all risks associated with use of material on this site. More here.

Cross-section of a canine uterus with fetuses

There are three substances that work together for a healthy delivery. I like to think of them as the Tres Amigos: Calcium, oxytocin, and glucose.

The uterus is a muscular organ that that contracts during labor so that puppies and placentas can be delivered. The frequency, strength, and endurance of contractions are all critical factors in a health whelping. The Tres Amigos work together to manage healthy deliveries.

Here's a quick summary of their roles:

  • Calcium—strength of contractions

  • Oxytocin—frequency of contractions

  • Glucose—endurance to maintain contractions over time


When most of us think about calcium, we think of bones and teeth. But calcium has other important roles in the body, one of which is muscle contraction. Muscles are made up of two main filaments: actin and myosin. In a health muscle contraction, these filaments grab each other and the myosin filament pulls the actin filaments, shortening (contracting) the muscle. This contraction is triggered when calcium binds to certain places on the filaments.

When there isn't enough calcium, the muscles can't contract strongly.

WARNING: Calcium supplementation should NOT be given before active labor clearly has begun. If you are not experienced enough to very confidently know the signs of labor then you should not give calcium until after the first puppy is born. If you are an experienced breeder and are very confident in your ability to identify active labor, then you can begin supplementing calcium at the onset of active labor. Giving calcium beyond what is in a balanced dog food prior to onset of labor can be LIFE THREATENING to your bitch. Giving extra calcium during pregnancy supresses her parathyroid gland and reduces her ability to manage available calcium during labor. If you surpress her parathyroid gland during pregnancy, that makes the gland "lazy" and it won't work efficiently during labor. That will cause her contractions to be weak and can induce eclampsia, which is life threatening. Giving calcium prior to active labor can cause the parathyroid gland to become inefficient (lazy) and lose it's responsiveness so that when whelping begins, it does not properly release calcium from the bones. The resulting low calcium in the blood of the bitch can be life threatening through nursing and signs of eclampsia should be considered a veterinary emergency.


Oxytocin is commonly known as the "love hormone" because it is produced when hugging or snuggling or playing with your dog. It is a wonderful social bonding hormone. Oxytocin also controls parts of the reproductive system, including contractions and lactation.

Oxytocin also helps control the rate calcium enters the cells of the uterus. It causes milk letdown into the teats. In a good example of the self-regulating nature of many biological systems, puppies suckling on teats produces more oxytocin. This is why it's a good idea to allow puppies to nurse between deliveries—their nursing helps produce the oxytocin needed to regulate contractions.

WARNING: Some breeders administer oxytocin during whelping. Oxytocin is a very strong hormone and while it can save dams and puppies in some instances, it comes with a lot of risk, including rupture of the uterus. In most cases, a dam will produce all the oxytocin she needs. If you administer oxytocin, do so only under the guidance of an experienced reproductive vet and as minimally as possible.


Glucose is the preferred fuel of the body. Your bitch will need a good supply of energy to manage the delivery of her litter. Delivery takes a lot of energy, and supplementing her energy supply is critical to a healthy whelping. Most bitches won't eat during whelping, and if they do vomiting can occur from the pressure of the puppies on the GI tract. We give a "milkshake" of goats milk and sugar or karo syrup between puppies to help with energy. Many breeders use similar formulas or plain ice cream.

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Hariamrit Khalsa
Hariamrit Khalsa

Love her book


Great suggestion about Myra’s books! She’s a wealth of knowledge!


Thanks, Ji. Great topic, as so many do not realize how the three work together and can be both life saving and life threatening. I just wanted to also point readers to Myra Savant Harris’ books for whelping and neonate care, which has extensive inform regarding the “tres amigos”, and so many other essential things breeders should know to prepare for whelping and emergencies. The books are invaluable! Thanks for your hard work in putting this site together! Shanti Marie Bates

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