Placenta

The placenta is an organ that develops during pregnancy and enables the exchange of nutrients and oxygen between the pregnant female dog and her puppies. It connects the foetus to the uterus of the female dog via the umbilical cord and ensures the supply and protection of the puppies.

Function of the Placenta in Dogs

The placenta performs several tasks during pregnancy:

1. Nutrient and oxygen supply: The placenta ensures that the foetus is supplied with nutrients and oxygen via the umbilical cord, which come from the mother’s bloodstream. This enables the growth and organ development of the puppies.
2. Removal of waste products: Waste products such as carbon dioxide and urea, which are produced during the foetus’s metabolism, are passed back into the mother’s bloodstream via the placenta and excreted there.
3. Hormone production: During pregnancy, the placenta produces hormones such as progesterone, which help maintain the pregnancy and prepare the female dog’s body for birth.
4. Protection of the foetus: The placental barrier, a selective barrier in the placenta, prevents many harmful substances and pathogens from passing from the mother’s bloodstream into the foetus. However, some harmful substances and pathogens can overcome this barrier.

Structure of the Placenta in Dogs

The placenta in dogs belongs to the type of zonary placentas. The contact between the uterus and the placenta takes place in a ring-shaped zone that runs around the foetus. This structure enables effective transfer of nutrients and oxygen between mother and foetus.

• Umbilical cord: The umbilical cord connects the foetus to the placenta and serves as a transport route for nutrients, oxygen and waste products.
• Placental barrier: This structure ensures that harmful substances and certain pathogens cannot enter the foetus.

Placental Separation and Birth

During birth, the placenta normally detaches from the uterine wall after the puppy is born. The afterbirth (placenta) is usually expelled shortly after the puppy. The female dog often eats the placenta, which is a natural process and serves to protect against predators. Consuming the placenta additionally provides the female dog with nutrients.

Possible Complications with the Placenta

In most dogs, the placenta fulfils its function without problems, however complications can occur:

1. Placental separation: Premature detachment of the placenta from the uterus can lead to an interruption of oxygen and nutrient supply. This is an emergency that can lead to death of the foetus if not recognised and treated in time.
2. Placental infections: Infections of the placenta, known as placentitis, can be caused by bacteria or viruses and often lead to premature births, miscarriages or the birth of weak puppies. Common pathogens are Brucella canis or herpes viruses.
3. Retained placenta: During birth, it can happen that one or more placentas are not expelled after the puppies are born. Retained placental remnants can lead to severe infections (metritis) or uterine inflammation. Veterinary assistance is urgently required in such cases.
4. Toxins and medications: Although the placental barrier filters many harmful substances, certain toxins, medications, or environmental pollutants can pass through the placenta and impair the development of the puppies. Especially certain antibiotics, corticosteroids, or drugs should be avoided during pregnancy.
5. Underdevelopment of the placenta (placental dysplasia): A malformation of the placenta can result in the puppies not being sufficiently supplied with nutrients and oxygen, which can lead to growth disorders or miscarriages.

Placental monitoring and health management during pregnancy

Vets monitor the female dog’s health during pregnancy to detect complications with the placenta at an early stage:

1. Ultrasound examinations: Ultrasound can be used to monitor the placenta and foetus and ensure that the placenta is developing correctly and fulfilling its function.
2. Blood tests: Regular blood tests can detect possible infections or imbalances in the female dog’s hormonal system that could affect the health of the placenta and the puppies.
3. Nutrition and care: A balanced nutrition and proper care of the female dog during pregnancy contribute to the healthy development of the placenta. Nutrient deficiencies can increase the risk of complications, so the female dog should receive all necessary vitamins and minerals.