At first, everything seems fine: Your foal was born without incident and started nursing as he should. But two days later, the baby quit suckling and began acting strangely--wandering around and pressing his head against the stall wall. Your youngster could have "dummy foal syndrome," one of the most common and costly problems requiring intensive foal care.
Dummy foal syndrome is a term applied to foals who demonstrate abnormal behaviors during the first few days of life, says Fairfield T. Bain, DVM, MBA, Dipl. ACVIM, ACVP, ACVECC, of Hagyard Equine Medical Institute in Lexington, Ky. "In reality, it really is a vague set of clinical signs that probably represent a collection of different disorders, from true birth asphyxia with abnormal brain function to other medical or surgical illnesses that result in a weak or sleepy foal that may show signs such as lack of affinity for the mare or seizures," he notes.
This medical condition is more formally known as neonatal maladjustment syndrome or hypoxic ischemic encephalopathy, says Carla Sommardahl, DVM, PhD, Dipl. ACVIM, assistant professor of equine medicine and pathology at the University of Tennessee Veterinary Teaching Hospital. Other common names for the condition have been wanderer foal or barker foal (because foals were reported to have abnormal vocalizations).
The exact cause is unknown, but it appears to involve asphyxia, or lack of oxygen, from any condition or illness in the mare or foal that leads to a decrease in oxygen or blood supply (ischemia) to the foal's brain or other organs during late gestation, delivery, or the early neonatal period, Sommardahl explains. She cites several causes:
- Maternal anemia, lung disease, cardiovascular disease, or hypotension (low blood pressure) secondary to endotoxemia or colic.
- Cases secondary to placental causes such as premature separation of the placenta, placental insufficiency (which could be caused by carrying twins), placental thickening (as occurs with fescue toxicity, placentitis, or placental edema).
- Foaling problems such as dystocia, Caesarian section, prolonged stage 2 labor, or oxytocin induction of labor.
- Common neonatal conditions leading to hypoxia/ischemia such as prematurity of the foal, recumbency secondary to another illness, lung disease in the foal, or anemia (lowered red blood cell level).
There are no known breed predispositions.
The most common clinical signs that suggest dummy foal syndrome, Bain says, are loss of affinity for the mare, wandering around aimlessly, head pressing, depression, not nursing, and, on occasion, profound convulsions.
"The most important thing to realize with birth asphyxia is that it affects the entire body, not just the brain, so you can have a foal that appears to be a 'dummy' that also may have intestinal problems, kidney failure, or abnormal heart rhythms," says Bain.
These signs generally appear right at birth or anytime within the first five days of life, depending upon when the initiating cause occurred and the severity of the damage.
Diagnosis and Treatment
"The diagnosis is generally made by clinical signs, history, and excluding other serious medical conditions, especially bacterial septicemia or other problems such as fractured ribs," says Bain. "There are some indicators in the blood work that are suggestive of placental dysfunction (elevated serum creatinine) that can support the diagnosis, but there is no specific test for the dummy foal syndrome."
Treatment is primarily directed toward supportive foal care, and it consists of supplemental nutrition, anti-inflammatory agents, antibiotics, and/or fluid therapy, along with medication to control seizures, if present. "Some foals will need to be fed through a stomach tube until they can nurse normally," Sommardahl reports.
"Early on, most of the medical efforts were toward reducing possible edema in the brain and controlling convulsions," Bain notes. "But in the past several years, much of the medical care has been based on the theory that the mechanisms involve the cascade of biochemical reactions following a period of birth asphyxia. Many of the medications used are intended to block some of the biochemical reactions known to occur following oxygen deprivation.
"Specifically, the amino acid glutamate has been shown to release into the brain tissue following asphyxia; it works as a cellular toxin by binding to receptors on nerve cells," Bain explains. "Magnesium, in turn, is supposed to block some of the toxic injury to the nerve cells by blocking the glutamate-binding site. Ascorbic acid--good old vitamin C--works as an antioxidant, but also has been shown to work by blocking the glutamate receptor."
Bain says that other antioxidants, including vitamin E and dimethyl sulfoxide (DMSO), might have some benefit in reducing nerve injury, and other categories of medications might block some of the other biochemical pathways initiated by asphyxia.
"The main difficulty," Bain says, "is that by the time the foal is showing clinical signs, the damage is already done. Still, these types of medications are used in hope of lessening further injury and decreasing the severity of the illness."
Another treatment option, where available, is hyperbaric oxygen therapy (HBOT), whereby the affected animal is placed into a high-pressure oxygen chamber. (In humans, these chambers are used to treat decompression problems in divers as well as trauma and various neurologic, orthopedic, and autoimmune disorders.)
"HBOT in veterinary medicine is the same as human medicine: The delivery of 100% oxygen under pressure to the patient," Sommardahl explains. "Oxygen is forced into the brain and tissues, organs, and fluids throughout the body through the pressurization of the hyperbaric chamber. The pressure we use is about 1.5 to 2.4 atmospheres (a pressure equal to that produced by 16 to 46 feet of seawater). This can be helpful in reducing edema in the brain tissue and increasing oxygen to damaged cells and tissues."
However, the role of HBOT in dummy foal syndrome is still somewhat unclear. States Bain: "Hyperbaric oxygen therapy is still considered a controversial area for birth asphyxia in human medicine, but there is research and clinical evidence that it can help salvage or reactivate injured nerve cells following birth asphyxia."
To date, much of what is done medically is solely based on the theory that the main mechanism involves birth asphyxia. "As long as other complicating medical disorders are ruled out, it is possible that a medical cocktail may be useful to block some of the biochemical reactions that occur secondary to birth asphyxia,"
At this point, veterinarians are trying to learn more about birth asphyxia through research using other animal models; this information is considered pertinent to equine foals. Additionally, Bain says, other drugs in the research pipeline will be added as more is learned from research into similar scenarios for human patients with asphyxia or stroke.
"It is possible that some day a combination of medications could be administered to at-risk foals (i.e., those with a difficult delivery or whose placenta was abnormal) to reduce the severity of the dummy foal syndrome," he predicts. "Hopefully, some advances will be made as the lessons of this research are applied to the clinical patients in the neonatal intensive care unit."
Chances for a good recovery depend upon the speed in which the disorder is diagnosed and treated and the severity of clinical signs. Says Sommardahl, "The more severe the signs, such as seizures, then the poorer the prognosis. However, if seizures and secondary or concurrent infections are controlled with proper medication and good nursing care, then these foals can do well."
Bain cautions that, as with many neonatal problems, dummy foal syndrome can encompass more than just a single problem or process. "Many weak foals develop bacterial infections subsequent to their weakness, have poor colostrum intake, or have secondary-to-birth injury," he says. "The good news is that once a foal recovers, he generally can go on to have a normal life with little or no long-lasting consequences related to the brain dysfunction."
Although many causes of dummy foal syndrome cannot be prevented, providing good pregnancy and neonatal care could reduce the foal's odds of developing this disorder and increase odds of survival. Sommardahl suggests:
- Preventing disease in the mare through good nutrition and vaccination.
- Avoiding fescue as a hay or pasture source for the pregnant mare, as that can cause a thickened placenta and difficult birth.
- Monitoring the mare for any placental changes via routine ultrasound examinations throughout the pregnancy, especially if she has had prior foaling problems.
- Checking the placenta after foaling for any thickening.
- Having the foal examined early if any problems occurred during foaling.
- Summoning the veterinarian if abnormal clinical signs are noticed in the foal.
"The expense for a foal in the neonatal ICU averages $1,000 per day," Bain states. "If a foal's stay in the hospital could be reduced by a single day, then some of the preventive measures might be worth the initial investment."
He also emphasizes that early identification of foals that are considered at-risk remains the key to a good outcome. "Waiting until an at-risk foal shows clinical signs before intervening could be likened to waiting and watching while Rome burns," he warns.
About the Author
Marcia King is an award-winning freelance writer based in Ohio who specializes in equine, canine, and feline veterinary topics. She's schooled in hunt seat, dressage, and Western pleasure.
POLL: University Equine Hospitals