Diagnosing and treating the neonatal foal

Diagnosing and treating the neonatal foal

Upper airway endoscopy, tracheotomy, radiography and chemistry profiles effective diagnostic tools
Mar 01, 2006

Dysphagia in the neonatal foal manifests itself as the presence of milk in the foal's nares after nursing. Milk reflux in a foal should not be ignored. Aspiration pneumonia is the usual secondary consequence.

Table 1: Causes of upper airway dysfunction in foals categorized by presenting sign of stridor
Foals with mild dysphagia can appear normal at birth except for the presence of milk at the nose. As aspiration pneumonia develops, wheezes and crackles may be heard on auscultation of the lungs. A rattle in the trachea from the aspirated milk often can be felt after the foal suckles. If obstruction of the upper airways occurs as part of the dysphagia, stridor, heightened upper respiratory noise and increased inspiratory effort can be prominent clinical signs (Table 1).

Differential diagnosis for dysphagia

The differential diagnoses for dysphagia in the foal are many and can include: dorsal displacement of the soft palate, rostral displacement of the palatopharyngeal arch, cleft palate, subepiglottic and pharyngeal cysts, bilateral laryngeal paralysis and arytenoid chondritis.

In a study of 38 foals with milk regurgitation/upper airway problems, 34 percent presented with dorsal displacement of the soft palate (DDSP). DDSP can be seen alone or in conjunction with rostral displacement of palatopharyngeal arch, redundancy of the soft palate or a persistent epiglottal frenulum. Prematurity, perinatal asphyxia and white muscle disease (nutritional myodegeneration, NMD) can be risk factors for the development of DDSP. In a review of 29 cases of NMD in foals, 52 percent of the foals presented with dysphagia as one of the clinical signs. Cerebral or brain stem disease may also influence the ability to swallow.

Unlike in humans where orofacial clefts, congenital fissures in the median line of the palate, are a common birth defect, cleft palate in the foal is very rare. The heritability of the cleft palate in the horse is unknown. The milk regurgitation is noted during the first nursing bout.

Subepiglottic and dorsal pharyngeal cysts also can interfere with the swallowing mechanism in the foal and cause upper-airway obstruction. These cysts are thought to originate from the thyroglossal and craniopharyngeal ducts, respectively.

Bilateral laryngeal paralysis and arytenoid chondritis have also been recognized in the newborn foal. Clinically these foals presented with respiratory distress. Laryngeal paralysis has been associated with cerebral diseases, such as congenital hydrocephalus. Arytenoid chondritis appears as an enlargement of the arytenoid cartilage and may mimic laryngeal paralysis.

Diagnostic Tests

Figure 1: Endoscopic view of a foal with DDSP. Note the displacement of the soft palate over the epiglottis and the mild rostral displacement of the palatopharyngeal arch (Equine Neonatal Medicine: A Case Based Approach, Spring 2006, Elsevier).
Upper-airway endoscopy is the most rewarding diagnostic test for finding the origin of the milk regurgitation. It is best performed with manual restraint of the foal because sedation might affect the findings. A 1-meter, 1-1.5 cm diameter endoscope can be passed easily in a foal less than 40 kg. Milk in the trachea is evidence that aspiration is occurring.