Microphthalmia, brachygnathia superior, and palatocheiloschisis in a foal associated with griseofulvin administration to the mare during early pregnancy.

This study investigates the adverse effects of griseofulvin on the foetus when administered to a mare during early pregnancy. The researchers focus on a single case involving a Friesian mare that was treated with griseofulvin due to dermatomycosis. The result was a foal born with bilateral microphthalmia, severe brachygnathia superior, and palatocheiloschisis, leading to its euthanization.

Study Methods and Observations

• The study was centred on an 18-year-old Friesian mare that was treated for dermatomycosis with griseofulvin during the second month of her pregnancy.
• The mare’s pregnancy proceeded without incident, and she gave birth to a male foal on the 331st day.
• Upon birth, the foal exhibited severe defects, including bilateral microphthalmia (an abnormal smallness of one or both eyes), brachygnathia superior (an undershot upper jaw), and palatocheiloschisis (a cleft in the lip and palate).
• Due to the severity of these defects, the foal was unable to survive and was humanely euthanized.

The Connection to Griseofulvin Administration

• The researchers associate the foal’s deformities with the administration of griseofulvin to the mare during her pregnancy.
• This is based on similar deformities being observed in other species to which griseofulvin was administered during pregnancy.
• The connection between griseofulvin administration and these deformities is further underpinned by the observation that the development of eyes and facial bones in horses happens primarily during the second month of pregnancy, which coincides with the period when the mare was treated with the drug.

Conclusion

• The researchers concluded that the severe defects observed in the foal were most likely the consequence of administering griseofulvin to the mare during her early pregnancy.
• This study indicates a potential risk of using griseofulvin during the early pregnancy of horses, and possibly other species as well.