Neonatal maladjustment syndrome (NMS) – also referred to as dummy foal syndrome – is a condition that causes neurological symptoms in foals.

This condition prevents the foal from performing normal behaviours, such as recognizing and feeding from the mare, standing and walking. Affected foals may appear lethargic, depressed, or display more serious clinical signs.

NMS can be caused by oxygen and nutrient deprivation in the foal before birth. It may also be caused by a failure of placental hormones to drop following birth.

NMS affects approximately 1-5% of foals and is primarily found in thoroughbreds. [1][2]

Although dummy foal syndrome is alarming to horse owners, the prognosis is generally good so long as the foal does not have any other health complications.

Neonatal Maladjustment Syndrome

Dummy foal syndrome is also known as neonatal encephalopathy or neonatal maladaptation syndrome.

Foals that have NMS are sometimes referred to as dummies, barkers, convulsives, or wanderers – terms that describe some symptoms of NMS. [3]

Foals diagnosed with NMS are usually divided into two categories: (1) normal at birth; and (2) displaying clinical signs at birth.

Normal at Birth

The first type of foals with NMS are born at term and initially appear healthy and normal. The foal will stand and nurse, but after a few hours will develop abnormal behaviours.

Affected foals will typically no longer recognize their mother (due to vision problems or confusion) and will be unable to suckle from the mare. [4]

Type 1 NMS is often associated with trauma to the chest while the foal passes through the birth canal. [5] The progression of NMS will vary depending on the foal and the specific causative factors.

The foal may wander aimlessly, unaware of his surroundings, or may lose his ability to stand completely. The foal might also flail his legs or may be completely limp.

Severely affected foals are unable to stand and will alternate between having seizures and falling into a coma. The foal’s temperature and heart rate rise during seizures and drop when the foal enters the coma. [6]

If the foal recovers, improved mobility is usually the first noticeable sign of recovery. The foal will learn or re-learn to stand, regain awareness of his surroundings, begin to recognize his mother and his suck reflex will return. [6]

Symptomatic at Birth

Type 2 foals are often born prematurely or experience complications during delivery. Type 2 foals may be underweight at birth and are more likely to have experienced inadequate conditions such as oxygen deprivation, before birth. The foal will begin to show signs of NMS before it is 4 days old, although symptoms are usually present immediately at birth. [5]

Healthy foals typically stand within an hour of birth and begin to drink from the mare within 2 hours of birth. [7]

Foals born with NMS usually will not stand and will have no suckle reflex, which prevents them from drinking from the mare or even a bottle. The foal will be very weak and will likely develop sepsis. Type 2 foals are prone to the same symptoms as type 1 foals, and their recoveries follow the same sequence.

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Signs

Foals that develop NMS will usually show a number of the following symptoms, which may come and go or may change as the condition progresses: [1][6][8]

  • Seizures
  • Tremors (shaking) in head and neck
  • Weakness or lethargy
  • Blindness
  • Staggering
  • Legs splayed; difficulty standing
  • Stiff legs
  • Disinterest in the mare or lack of recognition of the mare
  • Loss of suck reflex
  • Walking into things (due to blindness or lack of awareness)
  • Recumbency
  • Flailing legs while recumbent
  • Restlessness or over-excitement
  • Intermittent coma
  • Jaw champing or grinding teeth
  • Excessive saliva
  • Excessive licking
  • Tongue protruding out of mouth
  • Abnormal breathing or gasping for air
  • Vocalizations that sound like barking (often due to broken ribs)
  • Sweating
  • Constant ear flicking
  • Constant blinking

The affected foal might also experience the following health complications: [1][4][6][9][10]

  • Lesions on liver and/or kidney
  • Colic
  • Stomach ulcers
  • Ileus – decreased digestion caused by reduced intestinal muscle contraction
  • Necrotising enterocolitis – intestines become inflamed and begin to die
  • Retained meconium – foal cannot pass its first feces and becomes impacted
  • Weakened heart
  • Low or elevated heart rate and blood pressure
  • Collapsed lung
  • Sepsis
  • Kidney damage resulting in less urine production
  • Acidosis (blood pH below 7.3 and low bicarbonate concentration in the blood), leading to organ and brain damage
  • High red and white blood cell counts
  • Congestion in the lungs
  • High blood CO2

NMS may last anywhere from several hours up to approximately 30 days. [6]

Prognosis

The prognosis for foals that are asymptomatic at birth is good, with approximately an 80-87% survival rate. [8]

Foals that are symptomatic at birth were reported to have a survival rate of less than 50% in a 1996 study. [5] However, improved understanding and treatment of dummy foal syndrome may have resulted in higher survival rates since then.

Long-term neurological side effects of meonatal maladjustment syndrome in horses are rare.

Causes

NMS may be caused by hypoxic ischemia in which oxygen and nutrient deprivation cause the foal to display abnormal neurological symptoms.

NMS may also be caused by a failure of placental hormones to drop to normal levels in the foal after birth. [11]

Hypoxic Ischemia

NMS is sometimes called perinatal asphyxia syndrome or hypoxic-ischaemic encephalopathy because the foal may experience hypoxia and ischemia. [9]

Hypoxia describes a situation in which there is insufficient oxygen in tissues or the blood.

Ischemia refers to impaired blood flow to organs or tissues, interfering with oxygen and nutrient delivery.

Hypoxia and ischemia deprive the foal’s brain of oxygen and cause neurological damage, such as:

  • Lesions on the brain, spinal cord, and lungs
  • Cerebral oedema (fluid in the brain)
  • Brain bleeding
  • Neuronal death (death of neuron cells)

Neurons are the cells that communicate signals in the nervous system. These cells are responsible for sensing stimuli, determining how to respond, and relaying messages to the muscles. [9]

Symptoms will vary depending on the severity of oxygen and nutrient deprivation. [10] Hypoxic ischemia can also affect other organs. [9][10]

Causes of Hypoxia and Ischemia

Hypoxia and ischemia in foals can be caused by several different condition before, during, or after the foal is born, including: [4][6][10][13]

  • Respiratory disease
  • Endotoxemia (bacteria causing systemic inflammation in the mare)
  • Surgical delivery of the foal
  • Anemia
  • Placentitis
  • Separation of the placenta from the endometrium (the inner lining of the mare’s uterus), inhibiting blood delivery
  • Presence of twins
  • Fetal congenital defects
  • Dystocia (mare struggles to deliver the foal because of large foal size or because the fetus is in an irregular position in the uterus)
  • Sepsis (infection reaching the fetus’ blood causing inflammation, damage to multiple organs, and potentially lowered blood-flow to organs)
  • Fetal infection
  • Extreme pressure to the foal’s chest while passing through the mare’s pelvis during delivery, impacting the foals heart and lungs and disrupting circulation
  • Umbilical cord being cut too early

Premature cutting of the umbilical cord is one of the most common causes of dummy foal syndrome. [1] Cutting the cord too early prevents all of the blood from passing from the placenta to the fetus, depriving the foal of up to one-third of its blood volume.

Failure of Placental Hormones to Drop

Before birth, several factors keep the foal unconscious in the mare’s uterus and inhibit the foal’s central nervous system from functioning: [11][12]

  • Low levels of oxygen in the fetus’s blood
  • High levels of pregnancy hormone supplied by the placenta
  • The warmth and pressure of the uterus

After birth, the supply of placental hormones is cut off and most hormone levels drop significantly before the foal is two days old.

Declining hormone levels, higher blood oxygen as the foal breathes on its own, and exposure to the external environment cause the foal to gain consciousness.

This is important so that the foal can perform activities necessary for survival, such as learning to stand, walk, and nurse. [11][12]

In some foals with NMS, hormone levels remain elevated, which may explain the neurological symptoms. [11]

Research suggests that placental hormone levels drop after the foal is subjected to the pressure of passing through the birth canal. [2]

Foals that have a quick birth or that are born via C-section sometimes appear sleepy and limp after birth. They may be because they do not experience the same pressure from the birth canal.

Diagnosis

Diagnosis of NMS can be challenging because the clinical signs overlap with other neonatal foal conditions such as premature birth, infection, or hypoglycemia (low blood glucose). [9]

Your veterinarian will make a diagnosis based on the symptoms presented and conduct bloodwork to rule out other conditions.

Bloodwork is important to ensure there are no infections, sepsis, or low red or white blood cell counts. The veterinarian will also look for antibodies, which are passed from the mare to foal through colostrum – the first milk produced by the mare. [9]

High creatinine kinase and low blood glucose may also be observed in foals with neonatal maladjustment syndrome. [9]

Cerebrospinal fluid may also be assessed for high protein, indicating a problem with the central nervous system, as well as for blood, indicating a brain bleed. [9]

Treatment and Care

If your foal exhibits signs of dummy foal syndrome, contact your veterinarian for an accurate diagnosis. Several neonatal foal conditions share symptoms with NMS and must be ruled out.

Foals with NMS should be kept calm in a dark, quiet space to avoid stimulation. The foal should be kept under constant supervision to monitor for changes and to assist with feeding and maintenance. [6][10]

Recumbent foals should be adjusted every hour to avoid pressure sores forming from laying on one side for too long. These foals will also require support and assistance while learning to stand. [10]

Foals that are unable to recognize their mare or are unable to stand should be bottle fed with colostrum, mare’s milk, or milk replacer. Foals lacking the suckle reflex should be fed through a nasogastric tube inserted by a veterinarian. [6]

Colostrum contains vital antibodies from the mare and is important to help develop the foal’s immune system. Inadequate colostrum intake can make the foal more susceptible to disease.

Foals should ideally be fed every hour and receive a total of 10% of their body weight in milk or milk replacer per day.

Medications

If the foal is dehydrated or has diarrhea, your veterinarian may administer intravenous plasma. Foals may also receive oxygen therapy through a nasal tube. [6]

Foals with low blood sugar should be supplemented with a glucose and saline solution administered either orally or intravenously. A sodium bicarbonate solution may also be supplemented to combat acidosis. [4]

Vitamin K1 injections may be given if the foal shows signs of bleeding in a part of the brain called the cerebrum. [6]

Several medications can be given to treat seizures in the foal, including diazepam or phenobarbital. If the seizures persist, the foal may be anesthetized. [14]

Other treatments commonly administered to NMS foals include dimethol sulfoxide to address pain and inflammation, magnesium sulfate to treat impaction, omeprazole, as well as antioxidants: selenium, vitamin E, vitamin C. [10][14]

Madigan Thoracic Squeeze Technique

The Madigan thoracic squeeze is a technique that simulates the pressure that a foal would be exposed to when passing through the birth canal of the mare. [16][17]

This method is used to treat foals that display NMS symptoms because their placental hormones have failed to drop. Performing the squeeze may trigger a drop in hormone levels so the foal can stand and nurse. [2]

Foals that undergo the procedure are 3.7x more likely to recover from NMS and have a faster recovery. Over 80% of foals that have undergone the Madigan squeeze recover from NMS. [8]

The Madigan squeeze is performed by wrapping and tying a soft rope around the foal’s chest, neck, and ribcage in a particular configuration. [15]

Figure 1: How to Perform the Madigan Foal Squeeze Method [8]

Once the rope is correctly wrapped around the foal, the handler stands behind the foal and pulls on the end of the rope to exert 5-10 kg of pressure. The pressure should be maintained for 20 minutes. [2]

During the procedure, the foal will become limp, and sleepy and have a lower pulse and respiratory rate. [15] After the Madigan squeeze is completed, the foal should gradually begin performing normal behaviours such as standing, walking, recognizing its mother, and nursing. [2]

Precautions

This technique must be performed by a trained practitioner to avoid injury to the foal and should only be performed on foals younger than three days old. [2]

The Madigan thoracic squeeze technique is contraindicated in some cases. This technique could be harmful to foals with any of the following conditions: [2][8]

  • Broken ribs
  • Breathing difficulty
  • Heart disease or heart muscle weakness
  • Neuromuscular diseases
  • Sepsis

Prevention

There is no definitive way to prevent foals from being born with NMS.

However, addressing some of the risk factors for oxygen deprivation and abnormal hormone levels may decrease the foal’s likelihood of developing dummy foal syndrome.

You can reduce your foal’s risk of NMS by treating placentitis in the mare and avoiding cutting the umbilical cord too early.

There are lots of additional strategies to support your broodmare and improve the health of the developing foal. Consult with a nutritionist to review your breeding practices and optimize your feeding program.

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References

  1. Rossdale, P.D. Abnormal perinatal behaviour in the thoroughbred horse. Br Vet J. 1968. View Summary
  2. Millar, B. Performing the Madigan foal squeeze method to aid in the treatment of equine neonatal maladjustment syndrome. Vet Nurs J. 2019.
  3. Toribio, R.E. Equine neonatal encephalopathy: facts, evidence, and opinions. Vet Clin North Am Equine Pract. 2019. View Summary
  4. Baird, J.D. Neonatal maladjustment syndrome in a thoroughbred foal. Aust Vet J. 1973. View Summary
  5. Hess-Dudan, F. et al. Neonatal maladjustment syndrome and other neurological signs in the newborn foal: Part 1. Equine Vet Educ. 1996.
  6. Rossdale, P.D. Modern concepts of neonatal disease in foals. Equine Vet J. 1972. View Summary
  7. Rossdale, P.D. Clinical studies on the newborn thoroughbred foal: I. perinatal behaviour. Br Vet J. 1967. View Summary
  8. Aleman, M. et al. Survey of veterinarians using a novel physical compression squeeze procedure in the management of neonatal maladjustment syndrome in foals. Anim. 2017. View Summary
  9. Gold, J.R. et al. Perinatal asphyxia syndrome. Equine Vet Educ. 2015.
  10. Galvin, N. et al. Perinatal asphyxia syndrome in the foal: review and a case report. Ir Vet J. 2004. View Summary
  11. Aleman, M. et al. Abnormal plasma neuroactive progestagen derivatives in ill, neonatal foals presented to the neonatal intensive care unit. Equine Vet J. 2013.
  12. Mellor, D.J. et al. Responsiveness, behavioural arousal and awareness in fetal and newborn lambs: experimental, practical and therapeutic implications. N Z Vet J. 2003.
  13. Palmer, A.C. et al. Neuropathological changes associated with the neonatal maladjustment syndrome in the thoroughbred foal. Res Vet Sci. 1976. View Summary
  14. MacKay, R.J. Neurologic disorders of neonatal foals. Vet Clin North Am Equine Pract. 2005. View Summary
  15. Toth, B. et al. Evaluation of squeeze-induced somnolence in neonatal foals. Am J Vet Res. 2012. View Summary
  16. Equine and Comparative Neurology Research Group. Instructions to use the Madigan foal squeeze method. UC Davis School of Veterinary Medicine. 2017.
  17. Zonneveld, E. Causes and treatment of Neonatal Maladjustment Syndrome and review of the Madigan Foal Squeeze Procedure. Ghent University. Faculty of Veterinary Medicine. 2020.