Tetralogy of Fallot (TOF)

This disease is life-threatening and should be treated by a veterinarian swiftly.

Tetralogy of Fallot (TOF) is a congenital heart defect that affects horses. It is characterized by four main abnormalities in the heart: a ventricular septal defect (VSD), obstruction of the right ventricular outflow tract (RVOT), dextroposition of the aorta, and hypertrophy of the right ventricle. These abnormalities result in a reduced oxygen supply to the body and can lead to cyanosis, exercise intolerance, and sudden death. The severity of the condition can vary, and treatment options include surgery and medical management. However, the prognosis for horses with TOF is generally poor, and many affected animals have a poor quality of life or are euthanized.

Symptoms

Common in

Treatment

Treatment for Tetralogy of Fallot (TOF) in horses typically involves surgical correction of the defects present in the heart. The most common surgical procedure for TOF is a patch repair of the ventricular septal defect (VSD), which aims to reduce the flow of oxygenated blood from the left ventricle to the right ventricle, thus reducing the amount of deoxygenated blood that is pumped out to the body. In some cases, a trans-aortic balloon valvuloplasty or a subaortic stenosis resection may be performed to correct the obstruction of the right ventricular outflow tract (RVOT). In other cases, a transanastomotic conduit may be used to bypass the RVOT.

Medical management is also an important aspect of treatment, and can include administering oxygen, diuretics, and vasodilators to help improve blood flow and reduce cyanosis. However, the prognosis for horses with TOF is generally poor, and many affected animals have a poor quality of life or are euthanized.

Prevention

Prevention of Tetralogy of Fallot (TOF) in horses is not possible, as it is a congenital defect. However, breeding programs can avoid using horses with a history of TOF to reduce the incidence of the condition in future generations. Also, early diagnosis and treatment of horses with TOF can help improve their quality of life and prolong their survival.