Congenital cardiac defects in neonatal foals: 18 cases (1992-2007).

This study retrospectively analyzed medical records of neonatal foals diagnosed with congenital heart defects at a teaching hospital. Of the foals studied, Arabian foals were a significant portion, also including some foals exhibiting multiple defects. Horse breeds may have a specific predisposition to certain congenital defects, prompting further investigation.

Overview of the Study

• The study aimed to elucidate the clinically observable traits, diagnostic findings, the prevalence and the nature of congenital cardiac defects in neonatal foals. Research in this area until now has been limited to individual cases or small batch studies.
• Case files of neonatal foals (less than 15 days old) with congenital heart defects, recorded at William R. Pritchard Veterinary Medical Teaching Hospital between 1992-2007, were reviewed.
• The data collection involved recording history, signalment, clinical signs, laboratory data, diagnostic and necropsy results, and outcome. This comprehensive record-keeping allowed for detailed case analysis.

Key Findings

• 39% of the cases involved Arabian foals, suggesting higher predisposition to cardiac defects in this breed.
• Most common cardiac defects identified included Ventricular septal defect (VSD), tetralogy of Fallot, and tricuspid valve atresia.
• Typical clinical signs were a heart murmur of significant intensity (≥ 3/6), tachycardia (rapid heart rate), tachypnea (rapid breathing), and cyanosis of mucous membranes (blue discoloration due to low oxygen levels).
• In addition to congenital cardiac defects, many foals (50% of cases) exhibited other congenital anomalies, suggesting related or concurrent genetic factors affecting multiple organ systems.
• Two foals, both diagnosed with VSD, survived eight or more years post-diagnosis and one even proved to be a successful performance horse.

Implications and Conclusions

• The study indicates Arabian horses may be genetically predisposed to certain cardiac defects. Further research is needed to confirm this hypothesis.
• The study emphasizes the importance of comprehensive clinical evaluations when congenital defects are suspected due to observable symptoms like heart murmur, cyanotic membranes, or rapid heart rate and breathing in neonatal foals.
• Since concurrent congenital defects were found commonly, the study suggests that foals diagnosed with cardiac defects should also be evaluated for potential defects in other body systems.