Semilobar Holoprosencephaly Associated with Multiple Malformations in a Foal

Area of Science:

• Veterinary Pathology
• Developmental Biology
• Equine Medicine

Background:

• Congenital malformations in foals can significantly impact survival and welfare.
• Holoprosencephaly (HPE) is a spectrum of brain development disorders characterized by incomplete separation of the forebrain.
• Understanding the etiology and presentation of HPE in horses is crucial for veterinary diagnostics.

Observation:

• A full-term male foal presented with multiple congenital anomalies including wry nose, cervico-thoracic scoliosis, and atresia ani.
• Post-mortem examination revealed ileum atresia, right kidney agenesis, and a brain malformation consistent with semilobar holoprosencephaly (HPE).
• Specifically, there was incomplete separation of the rostral forebrain hemispheres and absence of olfactory bulbs and tracts (olfactory aplasia).

Findings:

• The case represents the first documented instance of semilobar holoprosencephaly (HPE) in a horse.
• This equine HPE case was associated with a constellation of other significant organ anomalies, indicating a complex developmental syndrome.
• The observed anomalies included facial, spinal, gastrointestinal, renal, and central nervous system defects.

Implications:

• This finding expands the known spectrum of congenital defects in horses.
• It underscores the importance of thorough post-mortem examination in foals with multiple malformations to identify underlying syndromes.
• Further research may elucidate the genetic or environmental factors contributing to such complex developmental disorders in equine populations.