Drugs for cardiovascular support in anesthetized horses.

This research article reviews the various drugs employed to support the cardiovascular health of horses under anesthesia. While balanced anesthesia and fluids are primary methods used, there often exists a necessity for further cardiovascular support via the use of various drugs, such as antimuscarinics, vasopressors, and inotropes.

Bradycardia and Hypertension

• The paper explains that Antimuscarinics are specifically employed for the treatment of bradycardia in horses where the slow heart rate condition is not caused by high blood pressure, also known as hypertension.

Hypotension and Vasopressors

• Vasopressors are drugs that constrict (narrow) the blood vessels, which leads to an increased blood pressure. These are deemed useful in situations where hypotension, or rather lower than normal blood pressure, is observed due to a condition known as vasodilation. Vasodilation is the widening or expanding of blood vessels resulting in lower blood pressure.
• Vasopressors are also used when the effect of fluids and inotropes is deemed insufficient. In most cases, fluids and inotropes are the initial strategy to combat low blood pressure in horses.

Inotropes: Scenarios and Types

• Inotropes, drugs that alter the force or energy of muscular contractions, are often favored in most cases. Specifically, sympathomimetics, calcium salts, and phosphodiesterase inhibitors serve as types of inotropes.
• Of the β-sympathomimetics, the research identifies dobutamine as the agent of choice. Dobutamine is a drug that mainly acts on the heart muscle and leads to increased heart contraction strength.
• Calcium salts are used primarily in horses that suffer from hypocalcemia, a condition where there’s a lower-than-average level of calcium in the bloodstream.
• The use of phosphodiesterase inhibitors, which are drugs used to block the action of phosphodiesterases, is briefly mentioned as possible alternative solutions. However, it is noted that more research in this area is required.