If your dog has been coughing or panting more than usual, it's important to take them to your veterinarian for a check-up. Pulmonary hypertension is a serious condition that can affect dogs of any breed, age or sex, although more common in smaller dogs. Left untreated, pulmonary hypertension can lead to heart failure. In this article, we'll discuss the causes, symptoms and treatments of pulmonary hypertension in dogs. By being aware of the signs and knowing what to do if your dog is diagnosed with pulmonary hypertension, you can help ensure they live a long and healthy life.
What is pulmonary hypertension in dogs and how is it different than systemic hypertension?
Pulmonary hypertension in dogs is a medical condition that affects the pulmonary arteries, which are the blood vessels that carries blood from the heart to the lungs. In dogs, pulmonary hypertension occurs when the pulmonary arteries become constricted or blocked, preventing blood from flowing properly. This can lead to a buildup of pressure in the pulmonary arteries, which can ultimately damage the heart and lungs.
Unlike systemic hypertension, which affects the entire body, pulmonary hypertension specifically affects the pulmonary arteries. While pulmonary hypertension can occur in any dog breed, it is most commonly seen in small breeds with an increased prevalence in West Highland White terriers. If your dog is diagnosed with pulmonary hypertension, it is important to work closely with your veterinarian to manage the condition and help your dog live a long and healthy life.
Several mediators play a role in the development of pulmonary hypertension in dogs and they all have the effect of constricting pulmonary arteries. Due to vasoconstriction in the pulmonary arteries, right-sided pressure overload to the heart occurs, resulting in heart enlargement on the right side. Congestive heart failure can eventually result.
What are the causes of pulmonary hypertension in dogs?
Pulmonary hypertension in dogs is classified into five groups based on the underlying cause. There are several specific disorders that can cause pulmonary hypertension and virtually any lung disease that results in areas of pulmonary vasoconstriction can eventually result in pulmonary hypertension.
Group 1: Pulmonary arterial hypertension
Congenital heart defects such as patent ductus arteriosis can result in pulmonary arterial hypertension and therefore cause pulmonary hypertension
Group 2: Left-side heart disease
Left-sided heart disease can result in pulmonary edema (fluid in the lungs) which can cause pulmonary hypertension.
Group 3: Hypoxemia
Hypoxemia means that the blood is low in oxygen. It can be caused by lung disease or high altitudes. When the blood is low in oxygen, pulmonary arteries constrict in order to send more oxygenated blood to the lungs. This vasoconstriction eventually leads to pulmonary hypertension.
Group 4: Pulmonary thromboembolism
Pulmonary thromboembolism is a condition in which a blood clot blocks one or more pulmonary arteries. If the blood clot is large or if there are many small blood clots, the pressure and resistance in the lungs increases and this can cause pulmonary hypertension.
Group 5: Parasitic diseases
Certain parasitic diseases such as heartworm disease and lungworms can cause pulmonary hypertension.
Group 6: Other
Other causes of pulmonary hypertension include Cushing's disease, protein-losing disorders (e.g. protein-losing enteropathy) and immune-mediated hemolytic anemia for example.
What are the symptoms of pulmonary hypertension in dogs?
The most common symptom of pulmonary hypertension is exercise intolerance. Dogs with pulmonary hypertension may get tired quickly during walks or playtime and may even have difficulty breathing. Other symptoms may include cough, fainting and weight loss. In some cases, dogs with pulmonary hypertension may also have a bluish tint to their tongue, gums or skin due to a lack of oxygen in the blood (cyanosis). If your dog is showing any of these signs, it is important to consult your veterinarian as soon as possible.
How is pulmonary hypertension diagnosed in dogs?
If your dog is showing signs of pulmonary hypertension, your veterinarian will likely perform a physical examination and take a detailed history. In order to confirm the diagnosis, your veterinarian may recommend several tests including chest x-rays, echocardiography, electrocardiography, pulmonary artery pressure measurement and blood tests.
Chest x-rays
Your veterinarian will be looking for signs of cardiomegaly (enlarged heart), pulmonary artery enlargement and a dilated vena cava to help assess the possibility of pulmonary hypertension.
Echocardiography (heart ultrasound)
Echocardiography is the most important non-invasive diagnostic test for pulmonary hypertension. It can help assess right-sided heart size and function as well as pulmonary artery pressure. The use of Doppler imaging is considered the best non-invasive test for pulmonary hypertension in dogs.
NT-proBNP blood test
NT-proBNP is a biomarker of cardiac workload and cardiac stress. It is useful in diagnosing pulmonary hypertension as well as assessing the severity of the disease and determining the prognosis.
What is the treatment for pulmonary hypertension in dogs?
The ultimate goal is to detect and treat any underlying disease (if possible), as well as reduce pulmonary hypertension to a level that improves the dog's quality of life.
Sildenafil is the treatment of choice for pulmonary hypertension in dogs. Sildenafil has been shown to lower pulmonary arterial pressure, and improve exercise capacity, and quality of life in dogs with pulmonary hypertension in multiple studies.
Supportive therapeutic options are also available depending on the cause of pulmonary hypertension including bronchodilators, diuretics and vasodilators.
What is the prognosis for dogs with pulmonary hypertension?
The outlook for a dog's condition varies depending on the underlying cause and how well they respond to treatment. Things that suggest a poorer outlook include severe cardiac disease and heart failure, as well as increased proBNP levels. The prognosis also gets worse when the condition is more severe or has developed over time because chronic pulmonary hypertension in dogs leads to permanent changes in blood vessels.
Sadly, the long-term survival rates in dogs with pulmonary hypertension are not favourable where a very small percentage (15%) are still alive 5 years after diagnosis, and the median survival time was 12 months.
In conclusion, pulmonary hypertension is a serious condition that can be fatal in dogs. There are many causes of pulmonary hypertension in dogs where any disease or condition affecting the lungs has the potential of causing pulmonary hypertension. Acute pulmonary hypertension in dogs is reversible but may not be recognized in the early stages. Chronic pulmonary hypertension leads to permanent and progressive vascular abnormalities. Common symptoms of pulmonary hypertension in dogs include exercise intolerance, coughing and difficulty breathing. If your dog is showing any signs of pulmonary hypertension, it is important to consult your veterinarian as soon as possible for diagnosis and treatment.