Dr. Mary Rose Paradis
Hypoxic ischemic encephalopathy (HIE), also called neonatal maladjustment syndrome, is a syndrome in the newborn foal that appears as a problem with the foal's mental function. Affected foals are said to be "dummy foals," "barker foals" and "wanderers." Sudden loss of suckle reflex
Encephalopathy refers to a problem with the brain. Hypoxia is the scientific name for decreased oxygen, and ischemic means a decreased supply of blood. Thus, HIE indicates a lack of oxygen and blood to the brain resulting in a pathologic condition.
The severity of the symptoms is probably related to the amount of hypoxia and ischemia that occurs normally during the birth process. After this initial insult the brain responds by swelling. This swelling is called cerebral edema. As the brain swells, there is an increase in the intracranial pressure, and it is this pressure that is responsible for the development of the clinical signs.
What to Watch For
Wandering away from the mare
Sleeping while standing up
Repetitive circling around the mare
The signs maybe present at birth or may occur in the first 72 hours of life. The foals with mild HIE, (lack of suckle) may recover in 24 to 48 hours. Foals that proceed to a more severe form of HIE (seizures and coma) may take 7 to 10 days of intensive support for full recovery to be achieved.
Veterinary care for the foal with HIE can be intensive and prolonged. It is focused on providing the foal with neurologic support in the way of seizure control and decreasing intracranial swelling of the brain. Anticonvulsants drugs and intravenous drugs that will reduce cerebral edema are used.
One needs to remember that it is highly likely that the HIE foal may not have suckled from his mother and thus has not obtained colostrum. It is important to provide the foal with protective antibodies through the administration of high quality colostrum, or if after 12 to 24 hrs, by administration of plasma intravenously. If the foal has not nursed and the mare has not dripped colostrum, then the mare should be hand milked and the colostrum given to the foal through a nasogastric tube, since the foal does not have a suckle reflex.
If the foal has lost his suckle reflex then he will not be able to feed himself. Nutrition must be administered through the use of an indwelling nasogastric tube. The tube is placed through the nose and into the stomach. It can be taped to the nose or sewn to the nostril so that the caretaker can administer milk on an hourly basis. A normal foal will eat 20 percent of his body weight in kilograms every day. This is essentially 9 to 12 liters of milk for the average sized foal. The total amount should be divided by 24 to give you the amount that you need to feed every hour. Initially, it may be difficult to administer this amount to a foal through a naso-gastric tube.
Recumbency – when the horse is lying down and cannot get up – may also create problems. It is important to keep the foal warm and dry. He will continue to urinate and defecate, and urine scalding can be a problem. It can be avoided by sponge bathing the foal, drying him and applying baby powder to the area. The baby powder absorbs the moisture.
Because foals do not have much body cushion in the way of fat, they are prone to developing pressure sores if they are unable to stand. The pressure sores develop over the bony prominences such as the elbow, the hock, the shoulder, the stifle and the hip. These pressure sore can develop quickly if the foal is on a hard surface. Even in deeply bedded stalls, the seizing foal will work his way down to the dirt floor. A soft cushion such as a lawn chair cushion helps to prevent this problem.
Home Care and Prevention
Careful observation of your newborn foal's behavior is important in the recognition of this problem. Newborn foals should show a desire to stay by their dam's side. They should be bright and aware of their surroundings. If they tend to wander away from the mare or don't suckle from the mare's udder then the foal is not showing appropriate behavior and you should begin to suspect that the foal may have HIE. This condition can change rapidly within hours so it is best that you alert your veterinarian as soon as you notice an abnormality.
In mild cases of HIE, the owner of the foal may wish to try and treat the foal at home. In more severe cases, this becomes difficult because the care is so labor intensive. It is difficult to provide the around-the-clock nursing care that the foal needs in order to survive. Referral to a hospital facility is usually the best decision for the foal's survival.
Because the hypoxic/ischemic event happens while the foal is still in the uterus or at birth, it is difficult to predict prior to birth which foal will be affected. Attended births may help in the delivery of foals that are distressed, thus decreasing the time that the lack of oxygen occurs. Sometimes during the delivery process, a red membrane appears at the vulva lips of the mare instead of the normal transparent amniotic sack. What you are seeing is actually the placenta coming out with the foal. This is called "red bag" and it caused by a premature separation of the placenta from the uterine wall. When this happens, the foal is unable to receive oxygen and nutrients from the mare. At the same time, the foal is still within the birth canal and cannot breath. This is an emergency situation. The red membrane must be cut open and the foal delivered as quickly as possible to minimize the amount of time that the foal is without oxygen.
If placentitis or twinning is suspected in your mare, then the mare should be sent to a facility that can provide care for the high-risk pregnancy. Mares that have had one foal with HIE are at higher risk of producing another. One should consider sending this mare to a hospital facility for foaling.