Heart disease in horses: Treatment and prevention

Disclaimer: This article, its content, and its related references do not constitute veterinary advice and should not be considered a substitute for veterinary care. If your pet is showing any symptoms that could indicate a medical emergency, please seek immediate emergency care.

Though cardiac disease is less common in horses than in other species, such as dogs and cats, it can be severe when it does occur. It’s important for horse owners to recognize clinical signs of heart issues in their horse, such as poor performance or a cough, in order to seek prompt veterinary care. In addition, some contributors to heart disease in horses can be avoided. If you have a horse, read on to learn about:

• Forms of heart disease in horses
• Common symptoms of equine heart issues
• The diagnostic process and treatment options for equine heart disease
• How some forms of heart disease in horses can be prevented

Abnormal heart rhythms (arrhythmias) and heart murmurs are some of the most common manifestations of heart issues in horses. Common heart conditions include septal or other structural defects, infectious myocarditis, and valvular disease. Some causes of heart disease include birth defects, infections, parasites, toxins, or a poor diet. Treatment for heart disease varies depending on the condition and may include heart medications, surgery, antibiotics, and other treatment methods to address underlying health conditions. Equine heart disease cannot always be prevented. However, owners can minimize the chances of their horse developing certain conditions, such as those attributed to infectious disease, toxicosis, or a poor diet.

Heart disease is any illness, defect, or disorder that affects the heart. Horses can have many different kinds of cardiovascular disease, and different heart conditions range in severity. Heart disease in horses is not common. However, when it does occur, it can be severe.

Types of cardiac disease in horses

Cardiovascular disease in horses can be congenital or acquired:

• Congenital heart disease: Condition is present at birth
• Acquired heart disease: Condition develops later in life

Congenital heart abnormalities in horses include:

• Ventricular septal defect
• Patent ductus arteriosus
• Tricuspid dysplasia (atresia)

Acquired cardiac diseases in horses include:

• Degenerative valve disease
• Endocarditis
• Myocarditis
• Cardiomyopathy
• Pericarditis

Heart arrhythmias, or abnormal heart rhythms, are common in horses and can be congenital or acquired. There are different types of cardiac arrhythmias in horses that vary in severity. Some arrhythmias are caused by an underlying heart condition, while others occur without the presence of cardiac disease.

Clinical signs of cardiac disease in horses

Clinical signs of heart disease in horses vary between conditions. Some signs are more severe than others and may include:

• Poor performance (ring sour)
• Exercise intolerance
• Increased breathing rate or shortness of breath
• Cough
• Weakness
• Lethargy
• Loss of appetite
• Loss of consciousness
• Collapse

Some cardiac conditions show few to no symptoms. Poor performance and exercise intolerance are often the first signs of heart disease in horses. However, they’re not exclusive to cardiac disease and can also be seen with other conditions.

Some horses may have heart murmurs (abnormal heart sounds caused by turbulent blood flow) that are not considered dangerous and do not lead to clinical disease. However, cardiac murmurs are common in horses with heart conditions, so listening for abnormal heart sounds is part of the diagnostic process.

Symptoms of equine cardiac disease are common in many other health conditions, so diagnostic tests are necessary to diagnose heart issues in horses. Diagnostics may include:

• Physical exam, including listening to the heart with a stethoscope
• Heart X-ray or ultrasound
• Electrocardiograph (ECG)
• Blood tests
• Blood pressure measurement

A heart X-ray, ultrasound, or ECG are needed to diagnose heart issues in horses. Once the heart condition is diagnosed, a treatment plan can be determined. Some forms of equine heart disease do not need immediate medical treatment but may require monitoring.

Treatment of cardiac disease in horses is specific to the type of heart condition. If needed, treatment options may involve:

• Heart medications, such as beta-blockers and diuretics
• Toxicosis treatment
• Surgery
• Antibiotics and anti-inflammatories for pericarditis
• Other treatment methods for underlying health issues

It’s important to talk to a veterinarian about treating your horse’s cardiac disease. Improper or inappropriate treatment delays effective treatment and may make things worse. If left untreated, heart conditions in horses can lead to congestive heart failure or even sudden death.

Not all causes of heart disease in horses can be prevented. However, there are some underlying contributors to some types of equine cardiac disease, including:

• Infectious disease
• Toxicosis
• Acute loss of electrolytes through excessive sweating
• Excessive supplementation of certain electrolytes

Some infectious diseases, such as the equine influenza virus, can lead to heart issues that can be prevented through vaccinations. Toxins that can lead to heart damage, such as through the ingestion of blister beetles, white snakeroot, milkweed, and other ornamental flowers, can be avoided. Although uncommon, a diet lacking sufficient vitamins and minerals may also contribute to cardiac disease in horses. Excessive electrolyte supplementation or the loss of electrolytes through sweating are more likely to lead to an acute cardiac event.

Many other heart conditions, such as congenital defects, cannot be prevented. “Routine physical examinations are one way that heart disease can be detected in horses before clinical signs appear,” explains Dr. Jamie Lecky, a veterinarian on the Vetster platform. However, some cardiac diseases will appear suddenly and with no warning. Sudden cardiac death (SCD) is most common in equine athletes, such as racehorses, and usually occurs during or shortly after periods of intense exercise.

If you would like to talk to a veterinarian about your horse’s risk for heart disease and ways you can help prevent it, a virtual vet appointment is a convenient way to talk to a professional from home.

How do you treat heart disease in horses?

Methods of treatment for heart disease in horses are different, depending on the individual horse and the specific condition. Once a cause has been determined, treatment may include medications to improve cardiac function, antibiotics, anti-inflammatories, surgery, toxicosis treatment, and treating any underlying health conditions contributing to the heart issue. Not all heart conditions require medical therapy.

What are the symptoms of heart disease in horses?

Symptoms of heart conditions in horses vary depending on the form of heart disease. Some conditions have few to no symptoms and may be benign, while others can cause symptoms such as poor athletic performance, trouble breathing, lethargy, cough, and loss of consciousness. In severe cases, heart disease can lead to congestive heart failure or sudden cardiac death (SCD).

What is the most common congenital heart defect in horses?

Ventricular septal defects are the most common congenital heart diseases in horses. This congenital defect affects the flow of blood through the heart due to abnormal openings, or holes, in the walls of the heart. Ventricular septal defects may cause little to no clinical signs when minor, but may lead to significant disease when severe.