Twins and multiple births

Twinning happens in humans but not in dogs & cats

Dogs and cats usually have multiple young at the same time. The average number of kittens is 4; the average number of puppies is related to the breed size: the larger the breed, the greater the number of puppies. Danes can have a dozen puppies, but a Boston Terrier may have 1 or 2 pups.

Twins are caused when the mother’s egg splits creating two offspring with the same DNA. If the egg splits before the sperm fertilizes it, the twins will have DNA from different fathers and are dizygotic twins. If the egg splits after the sperm fertilizes, both fetuses will have identical DNA from the mother and father. These are monozygotic twins.

Humans produce twins, but dogs and cats do not. The female dog (bitch) and cat (queen) do not have eggs that split and divide their DNA. There have been unusual cases of puppies found sharing the same placenta, which suggested they may be twins. When the DNA of these pups was tested, it was not identical, so they were siblings, not twins.

The healthiest and easiest dog and cat pregnancies and deliveries occur when there are several fetuses of the same size. If a dog or cat has only a single fetus, the mother often has a difficult delivery. This occurs because the single fetus is so well nourished that it grows too large to pass through the pelvic canal. These pets need C-sections.

The opposite is true for women—a single fetus is often healthier than multiple fetuses. Humans evolved to have more single births than twins or triplets. This happened because the drain on the mother raising multiple young of the same size decreased survival. Now, however, an increasing number of women are having multiple births. Our evolution is now influenced, according to the work of Dr. Gary Steinman, by cow’s milk, and modern reproductive technology. According to Dr. Steinman’s work published in the Journal of Reproductive Medicine May 20, 2006, there is an increase in twinning in humans who consume more milk. Vegan women do not show this tendency to twinning.

We began medically assisting reproduction with techniques like in vitro fertilization (IVF) in 1975, and the incidence of human twins has increased dramatically since then. However, current multiple birth rates are far higher than would be predicted with IVF and medically assisted reproduction. Steinman finds that women who drink milk and consume dairy products are 5 times more likely to have twins.

Steinman speculates that growth hormones given to cows alter a protein produced in human livers called insulin-like growth factor (IGF). IGF stimulates the ovaries to develop more eggs (follicles) and may help those eggs survive. There is a direct correlation between the amount of insulin-like growth factor in a woman’s blood and the likelihood she will have 2 or more babies.

The problem with multiple births is that it increases the likelihood of

• maternal high blood pressure (preeclampsia),
• the need for C-sections,
• that the babies will be premature, and
• of congenital defects.

In his previous research on twins, Steinman also published the following:

• Women who are breastfeeding are 9 times more likely to have twins than women who become pregnant when they are not breastfeeding.
• In vitro fertilization increases identical twins.
• Identical twins (monozygotic) are usually females.
• Identical twins (monozygotic) are miscarried more often than dizygotic twins whose DNA has some differences.
• The more fetuses in the uterus, the greater the likelihood the fetuses will have physical problems.
  

Perhaps this research suggests we should avoid promoting multiple births. It also suggests that eating hormone-stimulated meat products and drinking milk from animals stimulated by growth hormone has several health ramifications.

Dogs and cats consuming hormone-stimulated meat or milk, yogurt, whey, cheese and other dairy products may experience similar hormone-induced health problems. Because of this, look for pet foods that are hormone free.

Whether or not you’re planning to breed your pets and are concerned with their reproductive health, the pet food that’s best for overall health is Azmira. Your pet will love you for providing it.

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