What are Heart Murmurs?
A horse which has a more turbulent flow of blood or a higher rate of blood flow may have a heart murmur. A heart murmur is typically present in horses that have a heart condition or heart disease; however, some types of murmurs may also occur without these conditions. Heart murmurs can be the result of congenital defects or acquired within the horse’s life.
There are many causes of heart murmurs, and or in order for a veterinarian to find the cause of the heart murmur, the location, intensity, and timing must be found. The point at which the murmur is the loudest is known as the point of maximal intensity. The veterinarian may be able to differentiate the area of the aortic valve from the pulmonic valve in terms of the location and can also aid the veterinarian in an accurate diagnosis.
The heart murmur may be continuous, diastolic, or systolic in terms of timing. The actual length of the sound of the murmur can also give the veterinarian a great deal of information about the timing. Heart murmurs are categorized by a scale from 1 to 6. A grade one heart murmur is one that has a very low intensity and loudness, and a grade six murmur has a high intensity and is loud.
Heart murmurs in horses are caused by abnormal blood flow in specific areas of the heart. There are many types and causes of heart murmurs in horses, from mild to severe.
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Symptoms of Heart Murmurs in Horses
If your horse has a heart murmur, you may not notice until he is getting a normal physical exam by the veterinarian or if your horse has other, underlying conditions which prompt a veterinarian’s visit. Symptoms of a heart murmur may include:
- The whooshing sound heard with a stethoscope
- Subpar performance
- Reduced cardiac output
- Nasal discharge
- Heavy, labored breathing
- Heart disease
- Sudden death
There are several types of heart murmurs in terms of their intensity as well as their loudness. Heart murmurs are graded on a scale. Types of heart murmurs are:
- Extremely soft-sounding murmur only heard in a very quiet room with a stethoscope, grade 1
- A readily-heard murmur, yet still soft-sounding, grade 2
- A louder murmur that has some radiation, grade 3
- A louder murmur that has a wide range of radiation, grade 4
- A very loud murmur easily heard with a thrill, grade 5
- A very loud murmur that is heard off of the chest wall with a thrill, grade 6
Causes of Heart Murmurs in Horses
There are several different causes of heart murmurs. Some of the causes are mild conditions while others may be more severe. Causes may include:
- Aortic regurgitation
- Tricuspid regurgitation
- Mitral regurgitation
- Pulmonic regurgitation
- Ventricular septal defect
- Physiologic murmur
- Aortic stenosis
- Pulmonic stenosis
- Aorto-cardiac fistula
Diagnosis of Heart Murmurs in Horses
If you suspect your horse has a heart murmur, or if he is showing signs of one, make an appointment with your veterinarian. Typically, heart murmurs are suspected or heard by the veterinarian you’re your horse is at a routine physical examination or if he is at an appointment for another reason.
The veterinarian will be able to hear the heart murmur via stethoscope, or auscultation. The stethoscope can give other data for the medical professional, such as volume and the position of the beats as compared with the side of the heart.
The veterinarian will want to further investigate the heart murmur by performing an electrocardiogram. This is a tool that shows the medical professional the electrical impulses that the heart is performing throughout the organ. It allows the veterinarian to see the waves of controlled contractions.
The medical professional may also use an ultrasound to take a closer look at the valves of the heart, to take specific measurements of the walls of the heart as well as chambers. Ultrasounds even allow the veterinarian to closely see the direction and power of the blood flow through the heart.
Ultrasound scanning can be used to visualize the heart and therefore, assess the valves, take measurements of heart walls and chambers and even assess the direction and velocity of blood flow. Most murmurs are incidental and need only be monitored and then investigated further if the murmur worsens or there are signs of deterioration in the horse’s condition.
Treatment of Heart Murmurs in Horses
Treatment of your horse’s heart murmur is dependent upon the underlying heart condition which is causing the murmur. General treatment methods may differ, and may include:
In order to treat a heart murmur, your horse will need to undergo testing to find the root of the cause. Some heart conditions are mild and some require more medical treatment. If your horse’s murmur is the result of a heart condition, your veterinarian will explain your options for treatment once the condition is found and a definitive diagnosis is made.
Medication for your horse’s heart murmur may be prescribed after the veterinarian finds the underlying cause of the murmur. If your horse has a heart condition in which medication is effective, and this heart condition is causing the murmur, then medication may be a viable option. It will be important for the veterinarian to treat the underlying heart condition, if any, with the medication, and this may help the heart murmur as well.
Your horse may have a heart murmur that is a grade 1, 2, or even 3 in which the veterinarian will want to monitor over time to see if it worsens. If your horse is showing no other symptoms or discomfort, your veterinarian may recommend a watch and wait treatment method. Often, heart murmurs, namely lower grade ones, do not affect the horse’s work or performance.
Recovery of Heart Murmurs in Horses
Horses with heart murmurs that are not directly related to a serious illness have a good prognosis. In many cases, horses with this condition live a very long and otherwise healthy life. In cases of heart murmurs due to a heart abnormality or heart disease, the prognosis depends upon the type and severity of the condition.
If your horse’s murmur is related to a more severe heart condition, your veterinarian will guide you in making decisions for your horse’s health and future well-being. Every horse is different, and the heart issues which cause the murmurs are varied.
Once your horse has been diagnosed and treatment has begun, your medical professional will explain to you in detail what you need to do as a horse owner to further your horse’s recovery. He will also be there for you if you have any questions, see any new symptoms, or need advice on specific lifestyle changes your horse may need to undergo.
Many horses with murmurs do very well in life if they are in otherwise good health. Becoming educated on your horse’s diagnosis can also help you be more proactive in caring for your horse and learning of any other treatment or therapeutic options.
Heart Murmurs Questions and Advice from Veterinary Professionals
My horse was diagnosed with a moderate-severe heart murmur today. I couldn't there and all I was told was he could no longer be worked. Will he still live a decently long life?
Some heart murmurs in horses can be considered normal or may occur only after exercise (others may occur due to old age). The intensity and the valve affected will determine the severity of the murmur on a grade of 1 - 6. The severity would be determined by your Veterinarian (obviously) and their recommendation should be followed; horses with heart murmurs can live normal lives as long as they are not stressed which would put more stress on their heart (some exceptions apply). If there were other concerns, I would believe your Veterinarian would have advised you. Regards Dr Callum Turner DVM
My vet was just out - said that my gelding has a very bad heart murmur- loud and he was astonished by how bad. Nothing he can do. He is looking ribby on top and filling with fluid under barrel. He’s 11 years old. We are northwest PA. Any suggestions or help?
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