What is Pulmonary Hypertension (PHT) in Pets?
Pulmonary hypertension is a condition that affects the blood pressure in the arteries and capillaries of the lungs. The blood pressure in the lungs is much higher than normal in pets that suffer from pulmonary hypertension. The terms hypertension and pulmonary hypertension are often confused. Hypertension refers to systemic hypertension, and is high blood pressure throughout the body, whereas pulmonary hypertension is strictly high blood pressure within the lungs.
Pulmonary hypertension is normally a secondary disease, meaning that it is the direct result of another disease the pet has. There are many diseases and conditions that may cause PHT in pets, ranging from pneumonia, chronic bronchitis, left-sided heart disease, obesity, heartworm disease, Cushing’s disease, immune-mediated diseases, pancreatitis, and others.
Pulmonary hypertension is more prevalent in elderly animals, and is especially common in small breed dogs. The condition is relatively rare in large breed dogs and cats. Pulmonary hypertension affects more female animals than male.
Common Symptoms of Pulmonary Hypertension in Pets
Common symptoms of pulmonary hypertension in pets include:
Exercise intolerance
Labored or rapid breathing
Coughing, sometimes with bloody spittle present
Fainting
Weight loss
Abnormal lung sounds (crackles or wheezes)
Heart murmur
Cyanosis (when the tongue or gums turn blue or purple)
Distended abdomen or fluid build-up
Prominent jugular veins in neck in the limbs
Common Causes of Pulmonary Hypertension
Pulmonary hypertension in pets can be caused by a variety of underlying health conditions that lead to increased blood pressure within the lungs' arteries. One common cause is heart disease, such as left-sided congestive heart failure, where increased pressure in the left atrium causes a backlog of pressure into the pulmonary circulation. Another significant cause is chronic respiratory diseases, like chronic bronchitis or pulmonary fibrosis, which lead to long-term low oxygen levels and subsequent vascular remodeling in the lungs. Additionally, certain congenital heart defects, such as patent ductus arteriosus or ventricular septal defects, can result in increased blood flow to the lungs, causing pulmonary hypertension over time. Parasitic infections like heartworm disease also directly damage the pulmonary arteries, leading to increased pressure. These diverse medical instances highlight the importance of diagnosing and managing the underlying conditions to effectively treat pulmonary hypertension in pets.
Some common causes of pulmonary hypertension are:
Birth defects of the heart or lungs
Coughing (dry or “honking”)
Abnormal levels of the chemicals that regulate constriction or dilation of the blood vessels
Fibrosis (scarring of the lung tissue) caused by pneumonia or chronic bronchitis
Left-sided heart disease, which causes fluid build-up in the lungs
Living at high altitudes
Obesity
Tumors or blood clots blocking the pulmonary artery
Bacteria in the blood
Cushing’s disease
Immune-mediated diseases in which the pet’s immune system targets their own tissues
Pancreatitis
Changes to the heart muscle itself
If there is no known cause, then the pet’s primary diagnosis would be idiopathic pulmonary hypertension, which advises that a cause of the increased blood pressure could not be found.
Abnormalities of the Heart and Lungs can lead to Pulmonary Hypertension in Pets
Abnormalities of the heart and lungs can lead to pulmonary hypertension. In a healthy pet, the heart pumps deoxygenated blood into the lungs, where hemoglobin within the blood collects oxygen, and is pumped by the heart out to the rest of the body. Because the heart and lungs work in tandem, if there is a breakdown in this system, it can lead to pulmonary hypertension. Narrowing of the arteries or capillaries within the lungs, a blockage of the main artery into the lungs, high blood pressure within the left atrium of the heart, and excessive blood flow into the arteries of the lungs are all common heart and lung conditions that can lead to pulmonary hypertension.
How Changes to the Heart Muscle Can Lead To Pulmonary Hypertension in Pets
Changes to the heart muscle itself can also lead to pulmonary hypertension, as it disrupts normal blood flow into and out of the lungs. Unfortunately, pet's hearts can stiffen, enlarge and change with age and is often not preventable.
Some common changes to the heart that may lead to pulmonary hypertension are:
Heart muscle may become stiff and not expand to fill with blood appropriately.
The walls of the heart may become thickened, which prevents the heart from filling and emptying normally.
The mitral valves of the heart may become narrowed, which causes increased back pressure into the lungs.
A tumor may form in the upper chambers of the heart.
Diagnosing Pulmonary Hypertension in Your Pet
Diagnosing pulmonary hypertension relies on a number of diagnostic tests. Chest x-rays, blood work to test for clotting times and heartworm disease, and an echocardiogram are commonly used.
Seeking the care of a cardiologist or cardiopulmonologist is typically required for more advanced imaging and follow up, if your vet suspects pulmonary hypertension. The signs and symptoms of pulmonary hypertension are almost identical to that of left-sided congestive heart failure, so an echocardiogram and chest x-rays are required to confirm a diagnosis.
If you notice that your pet is experiencing any of the common symptoms of pulmonary hypertension, seek veterinary care right away.
Common Pulmonary Hypertension Treatment Options for Pets
Treatment options for pulmonary hypertension in pets focus on addressing the underlying cause and managing the symptoms to improve quality of life. For instance, medications like sildenafil (Viagra) are commonly used to relax and dilate the pulmonary arteries, reducing blood pressure within the lungs. Pets with heart disease-related pulmonary hypertension might benefit from drugs such as diuretics and ACE inhibitors to manage heart failure and reduce fluid buildup. In cases where chronic respiratory diseases are the cause, corticosteroids or bronchodilators can help improve lung function and oxygenation.
Additionally, pets with heartworm disease may require specific antiparasitic treatments along with supportive care to address pulmonary hypertension. Oxygen therapy can also be employed in severe cases to enhance oxygen delivery to the tissues and alleviate symptoms. These varied treatment approaches highlight the need for a tailored plan based on the specific cause of pulmonary hypertension in each pet.
Some common medications that may be prescribed by your vet for the treatment of pulmonary hypertension are:
Vasodilators - (e.g., sildenafil, tadalafil)
Inodilators - (e.g., pimobendan)
Bronchodilators - (e.g., albuterol)
Supplemental oxygen - (e.g., Pawprint Oxygen Cat or Dog Oxygen Kits or Oxygen Cages)
Diuretics - (e.g., Lasix)
Additional medications and treatments may also be needed if concurrent diseases are present with pulmonary hypertension.
Navigating a PHT diagnosis can be stressful for Pet Parents
Over time, pulmonary hypertension can lead to reduced blood flow and oxygen delivery to the lungs, as well as increased pressure and stress to the right side of the heart. Unfortunately, changes to the heart and lungs can be permanent. Treatment typically focuses on keeping your pet comfortable rather than curing the disease. The prognosis for PHT is very guarded, mostly due to the changes that can occur in the blood vessels of the lungs. However, with early detection and a comprehensive treatment plan, a pet may remain comfortable with PHT.
If heartworm disease or a congenital cardiovascular shunt is the cause of pulmonary hypertension, once treatment or surgery are complete, there is a chance that the patient can be completely cured of PHT, and will go on to live a normal, healthy life.
Prognosis depends on what the cause of the condition is, so navigating this diagnosis can be stressful for pet parents.
Maintaining a Good Quality of Life for Your Pet With Pulmonary Hypertension
Maintaining a good quality of life for your pet is possible despite a pulmonary hypertension diagnosis. Regular vet visits, maintaining a stress-free home, restricting your pet’s activity levels and salt intake, and decreasing environmental triggers that may lead to breathing difficulties can all help reduce the risk of an emergency. Having supplemental oxygen on hand in case of respiratory distress and making sure your pet’s medications and treatments are given as directed will also ensure that your pet visits the ER as little as possible.
If your pet has been diagnosed with pulmonary hypertension, it is important to know that there are treatments available to aid in the quality of life for your pet after diagnosis. The most important thing is to help your pet maintain a comfortable quality of life, which means keeping them as stress-free and happy for as long as possible.
