Dysphagia in Neonatal Foals
Foals should be able to swallow milk without backflow out the nostrils. The appearance of milk either dripping or pouring out the nostrils of newborn foals after nursing indicates a problem, specifically with swallowing. Abnormalities in swallowing are referred to as dysphagia and may result from a physical obstruction like a deformity or injury or loss of neurologic or muscular control of the swallowing structures.
In normal nursing, the foal wraps his tongue around the mare's teat and presses it against the roof of his mouth. The suckle creates negative pressure in the back of the throat, and milk flows into the mouth. As the milk bolus enters the back of the throat, it is trapped by the soft palate and subsequently squeezed by the muscles of the throat into the esophagus, the pathway to the stomach. Disruption of this process causes milk to regurgitate. At the same time it can also cause milk to be aspirated into the lungs.
Potential Causes of Milk Regurgitation
- Dorsal displacement of the soft palate
- Cleft palate or other congenital defects
- Pharyngeal weakness
- Vitamin E/selenium deficiency
- Laryngeal paralysis
- Hypoxic ischemic encephalopathy
Sometimes there is a snoring type noise associated with milk regurgitation. This is called stridor and is caused by a narrowing of the airways or laxity of the tissues of the throat. These signs require careful observation, as they may progress to labored breathing. In particular, look for extreme efforts to take air in. These signs are serious and may denote that the airway is the process of complete blockage. This obstruction can result from a severe collapse of the structures of the throat or the presence of a big congenital cyst in the airway. These foals have milk in their lungs and nostrils.
Your veterinarian should examine foals that have milk coming from their noses after nursing as soon as possible. If stridor or an increased respiratory effort is noted then it is an emergency. On physical examination, your veterinarian will attempt to sort out the cause for this problem.
An oral examination is helpful to determine if a cleft palate is present. A full cleft palate occurs when the two sides of the roof of the mouth fail to merge during in utero development. This creates a nasal passage that is directly open to the mouth and any milk that is in the mouth will simultaneously be in the nose. Sometimes the hard palate in the front of the mouth has closed as it should but the soft palate located in the back of the mouth is open. This is harder to visualize with an oral examination. A long bladed laryngoscope may be needed to see these structures.
Upper airway endoscopy is another important diagnostic tool for determining the causes of dysphagia with or without airway obstruction. This procedure involves passage of an endoscope up the nose of the foal. An endoscopy is a tube-like instrument that contains fiber optics, which allow examination of the structures in the nose and pharyngeal area. Cleft palate, soft palate displacement, pharyngeal paralysis and malformations can all be visualized if they are present.
Radiographs of the head may also aid in the diagnosis. It is highly recommended that radiographs be taken of the chest as well. Ninety percent of the foals with dysphagia will have aspiration pneumonia from inhalation of milk.
Treatment depends on the specific diagnosis. There is little that can be done for foals with a complete cleft palate. Surgical repair has been tried but has not been very effective. Pharyngeal cysts can be drained and removed. An emergency tracheotomy may be necessary in foals with severe stridor or increased respiratory effort due to an obstruction.
In cases where the dysphagia is secondary to weakness, soft palate displacement or pharyngeal paralysis, foals should be prevented from nursing their dams. Continued nursing will only worsen the inhalation of milk, causing aspiration pneumonia. These foals should be fed through an indwelling nasogastric tube until normal swallowing resumes. This may take anywhere from 2 to 20 days. Prophylactic Vitamin E/selenium supplementation may be helpful. Because of the aspiration pneumonia, all foals with dysphagia should receive antibiotics.
Home Care and Prevention
Owner of newborn foals should observe their foals during and after nursing for signs of milky nasal discharge. If a discharge is present then it is important to call your veterinarian immediately. The longer the foal is allowed to nurse with this condition the worse the aspiration pneumonia will be. Remember, it is important for the foal to receive colostrum. Your veterinarian should check immunoglobulin levels.
Care of these foals is probably best provided in a referral hospital. If the foal has a soft palate displacement, cyst or pharyngeal paralysis, it should be checked daily to see if the problem is resolving. The foal should also be fed every two hours through the nasogastric tube.