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Basics ⬇

Outline

BASICS

Overview!!navigator!!

  • Cleft palate (palatoschisis) is a rare defect of the secondary (hard and soft) palates
  • Congenital clefts result from an interruption of the midline closure of the embryonic palatine folds. Closure of the palate proceeds from rostral to caudal, so either the soft palate or both soft and hard palate may be affected
  • Acquired clefts result from trauma during surgery and may involve the hard or soft palate

Signalment!!navigator!!

  • Congenital cleft palate is seen in horses of any breed and gender, with a reported frequency of 4% of all congenital abnormalities. Age of presentation is often dependent on the severity of the cleft
  • Acquired clefts occur in horses of any age that have a history of recent surgery

Signs!!navigator!!

  • Milk draining from a foal's nose after nursing
  • Water- or food-stained discharge from the nares of adult horses
  • Coughing
  • Signs of aspiration pneumonia—fever, lethargy, increased respiratory rate, abnormal lung sounds
  • Chronic clefts—stunted due to lack of adequate nutritional intake and persistent respiratory disease
  • Horses >1 year of age may present for abnormal respiratory noise

Causes and Risk Factors!!navigator!!

  • Congenital—toxins, nutritional deficiencies, infection, hormonal and environmental factors, and metabolic abnormalities at the time of palate fusion (around the 47th day of gestation)
  • Acquired—iatrogenic trauma to the palate during pharyngeal or oral surgery

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Differential Diagnosis!!navigator!!

  • Esophageal obstruction
  • Dysphagia
  • Pneumonia

CBC/Biochemistry/Urinalysis!!navigator!!

CBC and fibrinogen—leukocytosis and hyperfibrinogenemia secondary to aspiration pneumonia.

Other Laboratory Tests!!navigator!!

  • Immunglobulin G assessed in all neonatal foals
  • Blood cultures indicated in foals with pneumonia or failure of transfer of passive immunity

Imaging!!navigator!!

  • Thoracic radiographs can determine the extent of aspiration pneumonia
  • Thoracic ultrasonography will provide information regarding the pleural surface

Other Diagnostic Procedures!!navigator!!

Endoscopy (nasal or oral) is essential to determine the extent and prognosis.

Treatment ⬆ ⬇

TREATMENT

  • Primary surgical closure of the cleft—transhyoid pharyngotomy for caudal clefts of the soft palate or a mandibular symphysiotomy for extensive soft palate defects or concurrent hard palate clefts
  • Extensive nursing care is required in neonates after surgery
  • Severity of aspiration pneumonia may increase anesthetic risk
  • Small defects at the caudal edge of the soft palate without signs of a respiratory infection may not require surgical repair
  • A laryngeal tie-forward has been described to treat dysphagia and respiratory infections for small, caudal defects in horses >1 year of age

Medications ⬆ ⬇

Outline

MEDICATIONS

Drug(s) of Choice!!navigator!!

  • Prompt administration of broad-spectrum antibiotics is indicated for respiratory infections
  • Antimicrobial combinations include sodium or potassium penicillin (22 000–44 000 U/kg IV every 6 h), an aminoglycoside (gentamicin in adults (6.6 mg/kg IV every 24 h) or amikacin in foals (25 mg/kg IV every 24 h)), and metronidazole (15–25 mg/kg PO every 8 h)
  • NSAIDS—for endotoxemia and inflammation (flunixin meglumine (1.1 mg/kg IV/PO every 12 h) or ketoprofen (1.1–2.2 IV every 12 h))

Contraindications/Possible Interactions!!navigator!!

Aminoglycosides and NSAIDS have negative renal and gastrointestinal side effects, especially in dehydrated patients.

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Patient Monitoring!!navigator!!

  • Evaluate the suture line by endoscopy no earlier than 1 week after surgery to prevent dehiscence
  • Monitor clinical signs of pneumonia, including temperature, respiratory rate, and effort
  • Follow progress of pneumonia by radiography for pulmonary lesions or ultrasonography for pleural lesions
  • Patients with extensive repairs, especially those involving the hard palate, should be fed via nasogastric tube to reduce the risk of dehiscence of the suture line

Prevention/Avoidance!!navigator!!

Owners are recommended not to breed animals with cleft palates, although inheritance is unknown.

Possible Complications!!navigator!!

  • Dehiscence
  • Incisional infection
  • Persistent soft palate displacement
  • Oronasal fistula
  • Pneumonia
  • Chronic nasal discharge

Expected Course and Prognosis!!navigator!!

  • Successful repair occurs in 50–60% of patients with midline clefts and minimal tissue loss
  • Clefts involving both hard and soft palate, >20% of the soft palate alone, or asymmetrical clefts have a poor prognosis
  • Prognosis is reduced by concurrent respiratory disease
  • Guarded prognosis for future athleticism—may also have persistent respiratory insufficiency after resolution of pneumonia

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Associated Conditions!!navigator!!

  • Aspiration pneumonia
  • Esophageal obstruction (choke)
  • Exercise intolerance
  • Pneumonia, neonate

Abbreviations!!navigator!!

NSAID = nonsteroidal anti-inflammatory drug

Suggested Reading ⬆ ⬇

Tate LP. Surgical repair of cleft palate. In: Hawkins J, ed. Advances in Equine Upper Respiratory Surgery. Hoboken, NJ: Wiley, 2015:195–206.

Author(s) ⬆

Author: Amelia S. Munsterman

Consulting Editor: Margaret C. Mudge