A disorder in new-born foals may offer a clue to autism in humans.
Veterinary researchers at the University of California, Davis, are teaming up with their colleagues in human medicine to investigate a troubling disorder in newborn horses and to explore its possible connections to childhood autism. The common link, the researchers suggest, may be abnormal levels of naturally occurring neurosteroids.
The horse disorder, known as neonatal maladjustment syndrome, has puzzled horse owners and veterinarians for a century. Foals affected by the disorder seem detached, fail to recognize their mothers, and have no interest in nursing. With around-the-clock bottle or tube feeding, plus intensive care in a veterinary clinic for up to a week or 10 days, 80 percent of the foals recover. But for horse owners, that level of care is grueling and costly.
“The behavioral abnormalities in these foals seem to resemble some of the symptoms in children with autism,” said John Madigan, a UC Davis veterinary professor and expert in equine neonatal health.
The maladjustment syndrome in foals also caught the attention of Isaac Pessah, a professor of molecular biosciences at the UC Davis School of Veterinary Medicine who investigates environmental factors that may play a role in the development of autism in children.
“There are thousands of potential causes for autism, but the one thing that all autistic children have in common is that they are detached,” Pessah said. Madigan, Pessah, and other researchers in veterinary and human medicine recently formed a joint research group and secured funding to investigate links between the two conditions.
“Foals don’t gallop in utero,” Madigan said, pointing out the dangers to the mare if a four-legged, hoofed fetus were to suddenly become active in the womb. The prenatal calm is made possible, he explains, by neurosteroids that act as sedatives for the unborn foal.
However, immediately after birth, the infant horse must make an equally important transition to consciousness. In nature, a baby horse would be easy prey for many natural enemies, so the foal must be ready to run just a few hours after it is born.
In short, somewhere between the time a foal enters the birth canal and the moment it emerges from the womb, a biochemical “on switch” must be flicked that enables the foal to recognize the mare, nurse, and become mobile. Madigan and Aleman suspect that the physical pressure of the birthing process may be that important signal.
“We believe that the pressure of the birth canal during the second stage of labor, which is supposed to last 20 to 40 minutes, is an important signal that tells the foal to quit producing the sedative neurosteroids and wake up,” Madigan said.
Amazingly, the veterinary researchers have found that they can reduce maladjustment symptoms in foals by using several loops of a soft rope to gently squeeze the foal’s upper torso and mimic the pressure normally experienced in the birth canal. After 20 minutes, about the same time a foal would spend in the birth canal, the rope is loosened and the squeeze pressure released.
In initial cases, the foals have responded well to the procedure and recovered, some rising to their feet within minutes and then bounding over to join the mare and nurse. The researchers suspect that the pressure triggers biochemical changes in the central nervous system that are critical for transitioning the foal from a sleeplike state in the womb to wakefulness at birth.
While larger studies are underway, the researchers have presented their results at national and international meetings of equine veterinarians, and many veterinarians and clinics are treating maladjusted foals with the squeeze procedure—now called the Madigan foal squeeze procedure.
Madigan cautions that, in spite of the strong observational effects, a larger, controlled clinical trial of national and international scope is now needed to reproduce those observed results and provide a better understanding of the mechanisms at work in the foals.
POSSIBLE LINKS TO AUTISM
The early findings have compelling implications for the health of newborn foals and have caused the researchers to also explore possible links to autism, which includes a group of complex brain-development disorders. “The concept that a disruption in the transition of fetal consciousness may be related to children with autism is intriguing,” said Pessah.
He and colleagues will look to see whether there are alterations in blood levels of certain neurosteroids that may serve as a marker for the disorder. They caution, however, that the relationship right now is just a theory that remains to be validated or disproven.
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