Also Known As
Hypoxic ischemic encephalopathy, barker, dummy foal syndrome, wanderer foal
Neonatal Maladjustment Syndrome or Hypoxic Ischemic Encephalopthy is also known as convulsive foal syndrome, dummy foal syndrome, barker or wanderer foal. The descriptive names given the condition are based on the actions and responses of the foal that result from damage to the central nervous system from a shortage of oxygen during or after delivery.
The foal often appears normal shortly after delivery, but within minutes or up to several hours, the foal loses its suckling reflex and begins to exhibit abnormal behavior. The behavior becomes progressively worse or fluctuates from near normal to seizures and spasms that involve the head, body, limbs and tail. The convulsions are accompanied by severe respiratory distress and the foal often emits strange high pitched barking of whinnying sounds.
The foal loses its ability to right itself and stand up. At this stage, the foal becomes inert and unresponsive. At times the foal may appear to be blind and may wander around bumping into objects. It doesn't respond to stimuli and this stage is referred to as "the dummy stage."
As a result of repeated convulsions, the foal may develop brain swelling, as well as respiratory, circulatory and thermoregulatory failure leading to death in approximately 50% of cases.
Foals that survive the convulsive phase have a favorable prognosis. Reflexes, including the sucking reflex, return gradually over a two- to three-day period. If the foal doesn't develop septicemia, and is able to stand and suckle within four days of birth, the prognosis is very favorable, provided no residual neurological deficit exists.
Extensive research has found that the conditions in a foal afflicted with behavioral abnormalities, the accompanying neurologic signs and the effects on organs make this syndrome much more complex than originally thought.
- Loss of sucking reflex
- Seizures or convulsions
- Emitting of strange, unusual whinnies or barking sounds
- Lack of coordination
- Respiratory distress
- Circulatory stress
- Signs of blindness
- Erratic movements and behavior
The syndrome is believed to be caused by central nervous system asphyxia (lack of oxygen) before, during or after delivery. Mares with placental infections, hydrops, or those that have a red bag delivery, where the placenta separates from the uterus, sometimes produce foals with the abnormalities of this syndrome. Premature foals are also susceptible.
The best prevention is careful selection of mares for breeding and making sure that the mare is well cared for during pregnancy and parturition. This includes careful attention to nutrition, exercise and general health.
First, and foremost, any newborn foal should be carefully observed for several days after birth for any signs of unusual behavioral traits or physical abnormalities.
If a foal shows any signs of seizures, it is important that a veterinarian assess the situation since control of seizures is important for both the neurological and physical health of the foal. Sometimes, turning the foal onto its sternum or helping the foal to stand is helpful.
Diazepam, Valium or an anti-epileptic drug may be given by intravenous injection for emergency control of seizures, but if continuing seizures occur, phenobarbital may be prescribed and used repeatedly until seizures are controlled. If phenobarbital doesn't work, phenytoin is sometimes prescribed.
Nasal oxygen can be of value and DMSO may be given to reduce brain swelling.
During seizures, it is important to protect the foal from injury by cushioning the area and making sure that it can't harm itself by knocking into hard, stationary objects. A clean, well-padded surface for the foal to lie on should be provided and all hay and straw should be removed.
During cool weather, prevent hypothermia by covering the foal with a warm blanket and raising the temperature in the stall or area where the foal is kept.
Foals that are not able to suckle should be given two quarts of mare's colostrum by nasopharyngeal catheter within 18 hours of birth.
Nutrition and water balance should be maintained by feeding the mare's milk or a warm milk replacer via nasopharyngeal catheter every hour at the rate of 20 percent of body weight per day, or as prescribed by a veterinarian.
The mare should be milked to obtain milk and to prevent her from drying up.
Since gastric ulcers are common in convulsive foals, preventative anti-ulcer treatment is usually prescribed.
Once the foal begins recovery, it will need training as it learns to walk, nurse and follow its mother.
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