Atrial fibrillation in a pregnant mare: treatment with quinidine sulfate.

This paper chronicles the successful treatment of a pregnant horse with atrial fibrillation using quinidine sulfate, a cardiac medication, without causing harm to the expected foal. The horse eventually succumbed to an unrelated intestinal condition.

Background of the Study

• Atrial fibrillation is an irregular heart rhythm that can lead to heart-related complications.
• This study involved a 15-year-old mare that was both pregnant and nursing a 70-day-old foal, experiencing atrial fibrillation.
• The researchers attempted treatment using quinidine sulfate, a drug often used to restore normal heart rhythm.
• The major concern was whether the treatment would impact the ongoing pregnancy or nursing of the younger foal.

Process of Treatment

• The maximum concentration of quinidine used was 4.3 mg/L in the mare’s milk, and 2.6 mg/L in the mare’s blood serum.
• The treatment was successful in converting the atrial fibrillation to normal sinus rhythm, indicating the effectiveness of quinidine sulfate in the context.

Effects of the Treatment

• The use of quinidine sulfate did not have detrimental effects on the pregnancy; the mare carried to term without complications.
• The drug levels in the milk and serum were closely monitored to ensure the safety of the nursing foal.

Post-Treatment Observations

• Unfortunately, the mare developed an acute volvulus (twisting of the colon) six months after treatment and subsequently passed away. However, this was unrelated to the heart condition or the treatment.
• The autopsy revealed no noticeable cardiac lesions or abnormalities, suggesting the mare’s death was not due to a heart-related issue that would handicap the credibility of the treatment process.
• In addition, the fetus was found to be both macroscopically and histologically normal, implying that the fetus did not suffer any developmental issues due to the mother’s atrial fibrillation or the treatment received.