Dogs get cell ‘hand-me-downs’ from older siblings

Microchimerism, a condition where a small number of cells in your body are not genetically your own, can be found in dogs as well as humans. (Credit: Mike/Flickr)

Researchers have discovered that a female dog can pass a condition known as microchimerism to her puppies while they are still in the womb.

The finding could help researchers pinpoint the health effects of the condition, in which dogs—and people—possess a small number of cells in their bodies that are not genetically their own.


Microchimerism most often occurs when a mother gives birth to a child. In some cases, cells from that child are left in the mothers’ body and continue to live, despite being of a different genetic makeup than surrounding cells.

A new study, published in Chimerism, shows evidence that those cells can then be passed on to other children the mother may give birth to at a later time.

“We already have some evidence that microchimerism may increase risk of thyroid disease while lowering the risk of breast cancer in women,” says Jeffrey Bryan, associate professor of oncology at the University of Missouri.

“The pet dog represents an excellent model of many ailments in people, and the presence of fetal microchimerism in dogs will allow studies which further clarify its role in health and disease.

Dogs and people

“Knowing that the condition can be passed on through birth will help us track the condition and its effects through several generations of animals.”

For the study, researchers found microchimerism in a female dog that had given birth to male and female puppies. The researchers found cells with Y-chromosomes in the mother after these births, meaning the mother had male cells present in her female body.

They also found genetically similar male cells in the mother’s female puppies from a later litter. Those puppies were newborn and had never been pregnant, strongly suggesting that they acquired the cells that were left behind by their older brothers while in the womb.

“These new findings are significant because they suggest that the movement, or trafficking, of fetal cells is quite extensive in dogs, as has been suggested in people,” Bryan says.

“This degree of cell trafficking can have an impact on health, disease, and therapy, including in transplantation.  The identification of this phenomenon strongly suggests that companion dogs will help us more rapidly understand the real impact of microchimerism in human medicine.”

The researchers plan to continue their research to follow the lifespans of dogs with microchimerism to determine to what diseases those dogs may be susceptible.

Source: University of Missouri