Severe phenylephrine-associated hemorrhage in five aged horses.

The abstract discusses a study on severe internal bleeding in older horses caused by the intravenous administration of the drug, phenylephrine. Resolution of this condition was only possible in one out of five horses with a blood transfusion while the others died from hemorrhagic shock.

Study Background

• The research focuses on five elderly horses (17 years and older) that developed severe internal bleeding or hemorrhage after receiving phenylephrine via intravenous infusion.
• This took place across three veterinary hospitals, emphasizing that these incidents weren’t isolated.
• Among these horses, severe hemothorax and hemoabdomen, or both, developed within minutes to hours after receiving phenylephrine. Hemothorax involves bleeding into the chest, while hemoabdomen involves bleeding into the abdominal cavity.

Observations and Results

• A majority of these horses (four out of five) died due to hemorrhagic shock, a severe loss of blood leading to organ damage and failure.
• Only one horse managed to survive the hemorrhage with the help of a blood transfusion.
• The exact source of the hemorrhage was successfully identified in only one horse, leaving the cause in the other horses unclear.
• The medical records of all horses with nephrosplenic entrapment of the large colon treated with phenylephrine at the University of Florida Veterinary Medical Center between 2000 and 2008 were also reviewed. Out of the 74 horses studied, three of them developed fatal hemorrhages.

Key Findings and Conclusions

• The study found that the risk of developing a phenylephrine-associated hemorrhage was 64 times greater in horses aged 15 years and above compared to those younger than 15 years old.
• Given these findings, the researchers conclude that the potential risks versus benefits of phenylephrine administration should be carefully evaluated, especially in older horses, due to the potential risk of severe and potentially deadly hemorrhage.