A horse’s heart is a remarkably durable and industrious organ, given the mountain of work it undertakes.

At around four kilos, it is responsible for supplying blood to a creature around 100 times its own weight, pumping up to 250 litres of blood per minute at maximum stress.

Identifying problems with a horse’s heart can be tricky because it functions in a slightly different way to the human heart.

A horse’s heart will vary from anywhere between 30 to 230 beats per minute, depending on activity but it’s how and when it changes that varies.

That rate can alter from beat to beat, triggered by as little as a sigh or shuffle and it is an indication of nothing other than a perfectly normally functioning heart.

Preventative care for horse heart health

An annual check up by an experienced equine veterinarian should include an evaluation of heart health with a stethoscope and this should be done more regularly for horses in training and competition.

Other diagnostics include bloods, x-rays and echocardiography, which may include testing under duress and can be undertaken if a problem is suspected.


Symptoms of horse heart problems

There are many indications your horse may have a heart problem.

The accumulation of fluid (edema) in limbs, chest, abdomen, lungs or jugular vein could point to heart failure. It may also trigger a persistent cough.

Other signs that may suggest an issue with your horse’s heart include:

  • Shortness of breath or difficulty breathing
  • Weakness
  • Intolerance to exercise
  • Tiring quickly during exercise
  • Loss of condition
  • Decrease in performance
  • Lameness
  • Abnormal gait
  • Fainting or collapse

Congenital heart disease in horses

This should be detected as soon as possible with a view to corrective surgery.

A horse with a congenital heart defect is at a much higher risk of dying prematurely, which is another reason why you should always get a pre-purchase assessment.

Horses with congenital heart defects purchased for competition purposes will not be able to perform to the required standards.

Common congenital heart defects include:

Septal defects – this is the most common defect and is a hole in the wall which separates the ventricles.

Patent ductus arteriosus – when the vessel in a foal that connects the pulmonary artery with the aorta fails to close after birth.

Tricuspid dysplasia – abnormal development of the tricuspid valve in the heart.

Tetralogy of fallot – causes a blueish tinge to the horse’s skin indicating there is not enough oxygen in the blood.

Atrial Fibrillation

This is a common type of arrhythmia especially among racehorses, and can occur during a race. It may or may not indicate underlying heart disease, and most horses recover without medical intervention.

Others may respond to quinidine sulphate which has its drawbacks because of its high levels of toxicity.

Electrical cardioversion is another option which involves shocking the heart back into rhythm in a similar way to a human defibrillator.

The difference is that because of the size of a horse, the electrodes are not effective externally.

Hence, they must be thread down the veins of an anaesthetised horse and placed into the heart itself.

Heart murmurs

Also known as valvular regurgitation or a leaky heart valve, this occurs when a valve stops the reverse flow of blood.

It is more likely to present in horses at least 10 years old and can be diagnosed with an echocardiogram .

Unfortunately, there is no treatment or cure.

Horses with heart murmurs generally need to have their workload reduced or be retired as they may no longer be safe to ride.

Other potential heart issues in horses

Sudden death in horses is very rare but may be caused by the rupture of a major blood vessel such as the aorta. 

There are a number of other causes of heart ailments in horses and these include:

Viral infections – influenza, infectious anemia and arteritis have no effective treatments with rest and supportive care the primary course of action.

Bacterial infections – streptococcus equi (strangles) and rhodococcus equi can be treated with antibiotics.

Thrombophlebitis – thrombosis of the jugular vein as a result of injection or contamination, normally treated with hydrotherapy, anti-inflammatories and dimethyl sulfoxide.

Treatment and recovery

Treatments vary widely depending on the diagnosis.

They may include anything from medications and anti-inflammatories to balloon-dilation, aimed at widening the heart valves, and open heart surgery.

Some medications may trigger side-effects which need to be monitored closely with follow-up visits which are also likely to include further diagnostic tests.

Pain relief will also be prescribed and the horse will need to be restricted to very limited exercise while it recovers.

Prognosis relies heavily on the extent of the disease when diagnosed with some horses requiring lifetime medication.

Contact us today

If you suspect your horse may be suffering from a heart problem, it is critical you seek the assessment of an experienced equine veterinarian at once.

Early intervention is essential to help prevent the advancement of serious heart disease.

Dr Ian Church and the Newmarket Equine are accomplished in the diagnosis and treatment of all types of equine heart disease.

They will recommend the most appropriate course of action, design a treatment plan and provide further diagnostic tests should they be required.

Please contact the office for more information.

The information contained on this article is general in nature and does not take into account your horse’s individual needs. You should consider whether the information is appropriate to your horse’s needs, and seek professional advice from a qualified vet.

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