Equine practitioners dealing with newborn foals might be familiar with the Madigan Squeeze Technique. The technique helps revive a “dummy” foal suffering from neonatal maladjustment syndrome (NMS).
There is a story behind how John Madigan, DVM, DACVIM, DACAW, professor emeritus of the University of California, Davis, developed the brilliant and simplistic concept of using a rope squeeze to address this neonatal crisis. It is a study in thinking outside the box while following the science.
In a webinar sponsored by the Equine Veterinary Practice Company of New Zealand, Madigan explained the pathophysiologic reasoning behind the squeeze technique and how he and researchers arrived at this remarkable protocol.
About Neonatal Maladjustment Syndrome (NMS)
Historically, practitioners have attributed NMS to some hypoxic or asphyxiation event occurring to the foal during birth. Madigan got to thinking that there is more to the story than simply a hypoxic injury during the birth process. As many as 80% of NMS foals recover within three to five days when supported and treated for symptomatic problems related to their extended somnolence following birth. He noted that recovery is complete. The foal does not have neurologic deficits that one might expect from hypoxic injury. Rather, the foals act entirely normal, as if there never had been any delay or problem outside the womb.
The thought is that there must be some kind of signaling process that moderates the extended “anesthesia” that keeps a foal quiet in utero for 11 months. Once born, the foal awakens, stands within an hour or two, bonds with its dam, and begins nursing within two to three hours. Soon, the neonate is exploring its new world and galloping around on nimble legs.
But, for the NMS foal, these events do not happen. The foal either cannot get to its legs or it wanders aimlessly, doesn’t recognize its dam, and is pretty much asleep on its feet or lying recumbent. Sometimes, curls into a ball much like it would in the uterus.
Causes of NMS
While on sabbatical in New Zealand in 2005, Madigan attended a welfare lecture that discussed neurosteroids in sheep. The study was entitled Progesterone Derivation and Anesthetic Neurosteroids. This was the first he’d heard of this concept. Looking back through the literature, he discovered that in 1988, Dr. Peter Rossdale had observed that NMS seemed to be associated with a rapid birth. It is also associated with cases where human intervention had hastened a foal through the birth canal.
Measurements by Rossdale in 1991 of plasma progestogens in the mare, fetus and newborn identified that progesterone transforms to allopregnanolone in both the placenta and fetal brain. This neurosteroid is responsible for keeping a foal asleep by working on GABA receptors much in the same way that barbiturates or anesthetics do.
Compared to a normal foal, total progestins in NMS foals reach very high levels. They remain high rather than rapidly declining after the first hour postpartum, as with normal foals.
When Madigan measured neurosteroids, he found progesterone levels 80-fold higher than controls. He also found other neurosteroids as much as 3,000 to 12,000 times higher than in normal foals. NMS foals also had higher levels of DHEA. This works as a sedative and lowers body temperature, both typical signs of maladjustment.
In addition, studies discovered that septic foals often have highly abnormal levels of neurosteroids.
Madigan identified multiple roles of neurosteroids:
- They modulate the GABA brain receptor, which is central to consciousness and important for brain development and function.
- Steroids exert organizational and motivational actions during brain development and also modulate neuro-transmission.
- Certain steroid compounds, especially 5-alpha-reductase pregnanes, can cross the blood-brain barrier to exert neuro-modulatory effects on neuroactive steroids.
- Pregnane metabolites are primarily synthesized within the central nervous system from cholesterol via progesterone by the action of 5-alpha-reductase. They can also be synthesized in other tissues and readily cross the blood-brain barrier.
- The brain GABA receptor works as a chloride ion flux that can open or close with immediate effects. It also influences gut motility, the vagus nerve, autonomic regulation, and phasic and tonic inhibition on consciousness.
Madigan summarized that NMS was associated with persistence of hormones secreted in utero to keep the foal in a sleep-like state during pregnancy andas the foal advances through the birth canal. He pointed out that the CNS and mentation are depressed in utero just like in an NMS foal. While in utero, no ventilation is needed, and an NMS foal demonstrates poor ventilatory efforts. Due to placental and maternal functions in utero, there is minimal need for gastrointestinal motility, urine output, thermoregulation, pain responses or ambulation. An NMS foal demonstrates similar poor or absent responses to these stimuli or functions.
The Research Tested
To continue the search for a signaling process to advance a foal’s ability to transition to life outside the uterus, Madigan’s research team infused allopregnanolone into a normal foal. Within moments, the foal became ataxic and recumbent due to the effects of the hormone on the brain. Limp, floppy limbs were typical, and likely of benefit in utero. Using a lower dose of allopregnanolone, the team measured brain waves. They found that the foal lapses into a non-REM form of sleep.
These same brain wave changes and sleep state occur in a foal laid down through the rope squeeze process.
Rather than the term “neonatal maladjustment syndrome,” Madigan suggested that a more accurate way to view this may be as “failure to transition to consciousness at birth.” The abnormally adjusted foal fails to bond to its dam, fails to locate the udder to nurse, is disoriented in its environment, and often wanders aimlessly around the stall or paddock. In essence, he is still asleep as if he remains in the womb.
The Solution: Madigan Foal Squeeze Technique
We are all familiar with the tendency of a foal to crumple when human arms encircle and hold them firmly. Yet there is no way for a person to maintain that pressure on a foal to achieve a steady state of quiet. The only tool needed to accomplish this technique is a smooth rope that slides easily. It is started around the foal’s chest, wrapped behind the elbow, and secured with a bowline knot. Then a couple of snug half-hitches around the sternum and chest finish it off, keeping the rope in front of the umbilicus. The rope operator then gently but firmly tugs on the rope. The foal slowly folds up onto the ground, immediately falling into a sleep state.
The squeeze technique requires 20 minutes of a steady gentle pull to achieve a smooth brain wave while the foal is recumbent. It provides predictable somnolence with the foal experiencing non-REM sleep and slow wave brain activity. Heart rate, respiratory rate and body temperature all drop. The foal’s pain threshold increases, endorphins release, and so does ACTH despite no evidence of stress. There is no change in venous blood gases, and the method is extremely safe.
It has value for other procedures that require foal cooperation, such as plasma infusions, ultrasound studies, radiography and some surgical procedures. This way, you don’t have to resort to administration of sedatives or general anesthesia.
Why the Madigan Foal Squeeze Technique Works
During the 20 minutes of somnolence using the rope technique, two hormones elevate to maintain the foal in a sleep state. Madigan pointed out that in normal circumstances, 20 minutes is a comparable duration for Stage 2 labor in a mare. The foal remains asleep enough to not wiggle or change position as it passes through the birth canal. Then, once that duration of squeeze is finished, the anesthetic effect is dialed down to transition the foal from 11 months of “sleep” in the womb to an active foal interacting with its new world environment.
When the rope squeeze is finished and the rope is removed, the foal awakens, stands up, shakes, nickers to its mom and begins searching for the udder. The miracle is that nothing anyone has done up to that point with a dummy foal has been able to awaken the foal from its stupor. The rope squeeze method works completely.
Once the researchers had identified the biochemistry of transition from womb to world, they tested it on myriads of foals worldwide. They found that the rope squeeze technique worked every time, even on NMS foals a few days old. It costs nothing to use and gives a foal a chance at a normal life. Not all NMS foals make it when only receiving supportive medical treatment the old-fashioned way.
The Septic Foal
A foal with sepsis certainly needs ancillary medical treatment, but the rope squeeze technique used in conjunction hastens recovery.
This technique is applicable to all animals, including sheep, goats and cattle. It also resembles the swaddling method that calms human babies and helps them relax and sleep.
Take-Home Message: Merits of the Madigan Foal Squeeze Technique
It is so simple and so elegant—yet so complex—how Mother Nature sets up biochemical and physical controls to keep mare and foal safe.
Madigan and his team have given equine practitioners specializing in reproduction an inexpensive and transformative technique to get a “dummy” foal on its feet. This technique enables equine veterinarians to jump-start foals to exhibit expected, normal behaviors by a newborn.