Maladjusted foal syndrome
In newborn foals, the disorder known as neonatal
maladjustment syndrome or dummy foal syndrome occurs
in only three to five percent of live births, but when it does
appear, it is, said one Thoroughbred horse breeder, “a
nightmare.”
With continuous treatment, including around-the-clock bottle
or tube feeding plus intensive care in a veterinary clinic, 80
percent of the foals recover. But that level of care — required
for up to a week or 10 days — is gruelling and costly.
For years, the syndrome has been attributed to hypoxia —
insufficient oxygen during the birthing process. Typically,
when a foal’s brain is deprived of oxygen, the resulting effects
include mental deficits, abnormal behaviour, blindness and
even seizures, and, as in human babies, much of the damage is
serious and permanent.
“We believe that the pressure of the birth canal during the second
stage of labour, 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.
‘There are reports of very sick newborn babies … making seemingly
miraculous, spontaneous recoveries after being placed in the arms
of a grieving parent for a last embrace.’
— John Madigan
The theory, he said, is supported by the fact that the maladjusted foal
syndrome appears more frequently in horses that were delivered via
caesarean section or experienced unusually rapid births. Perhaps those
foals do not experience significant physical pressure to trigger the change
in neurosteroids, Madigan said.
But is oxygen deprivation the culprit?
Oddly, however, most foals with neonatal maladjustment
syndrome survive the ordeal and have no lingering health
problems. This raised the question of whether hypoxia was
the culprit in the syndrome, and Madigan and UC Davis
veterinary neurologist Monica Aleman began sleuthing
around for other potential causes.
One of their prime suspects was a group of naturally occurring
neurosteroids, which are key to sustaining pregnancies in
horses, especially in keeping the foal “quiet” before birth.
Neurosteroids persist in the bloodstream
Furthermore, the research team has found for the first time
that sedative neurosteroids persist, and their levels often
rise, in the bloodstream of foals born with symptoms of the
maladjustment syndrome. These neurosteroids are known to
be able to cross the blood-brain barrier and impact the central
nervous system, acting on the same receptor, as do sedatives
and anaesthetics.
The researchers also have demonstrated that maladjustment
symptoms can be brought on temporarily in normal, healthy
foals by administering short infusions of a neurosteroid called
allopregnanolone. When the neurosteroid levels drop, the foals
return to their normal state.
No galloping in the womb
‘Foals don’t gallop in utero.’
— John Madigan
“Foals don’t gallop in utero,” Madigan is fond of saying, pointing out
the dangers to the mare if a four-legged, hoofed foetus were
to suddenly become active in the womb. The prenatal calm
is made possible, he explained, 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.
Biochemical ‘on switch’
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 recognise the mare, nurse, and become mobile. Madigan
and Aleman suspect that the physical pressure of the birthing
process may be that important signal.
Foals ‘wake up’ with gentle harness pressure
Amazingly, the veterinary researchers have found that they
can reduce maladjustment symptoms in foals by using a
simple rope harness to gently squeeze the foal and mimic the
pressure normally experienced in the birth canal.
To recreate that pressure, the researchers developed a
method for wrapping a foal’s upper torso with several loops of
a soft rope, creating a temporary harness. When pressure is
applied with the rope, creating a gentle squeeze, the foal lies
down and appears to be asleep.
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, bounding over to join the mare and nurse, as
shown in the video.
The ‘Madigan Foal Squeeze Procedure’
The researchers suspect that the pressure triggers
biochemical changes in the central nervous system that are
critical for transitioning the foal from a sleep like state in the
womb to wakefulness at birth.
July• August 2015 • The Australian Quarte ȁ!