Pulmonary hypertension in cats – Symptoms, causes and treatment

La pulmonary hypertension in cats (HP) is considered a complex syndrome that is characterized by a Elevation of blood presure inside the structures that make up the vascular network of the lungs. In the veterinary clinic, PH includes various clinical manifestations and is usually classified according to its etiology (identification of the cause) and its pathophysiological mechanism (behavior and evolution in the organism).

Although this pathology has a low incidence in the young population, it can appear with certain frequency in the elderly felines, whether mestizo or of a defined race. Of course, we must emphasize the importance of go to the vet Trusted by observing any change in the appearance or behavior of your pussycat.

However, in this article, we explain the main Symptoms, causes and risk factors of pulmonary hypertension in cats, to help you early recognize the signs of this disease in your feline.

What is pulmonary hypertension?

The lungs The felines have a vascular network of high capacity, but low pressure and resistance, which is directly involved in the process of respiration and oxygenation of the tissues of your body. To establish a comparison, the resistance of the cardiac (systemic) vascular network can reach 10 times higher than the pulmonary one in healthy individuals. As a result, the cardiac structures are prepared to withstand a much higher pressure than the pulmonary arteries and veins network.

However, the presence of certain diseases, malformations or risk factors can cause a increase in pressure and resistance of pulmonary vascular structures. This pulmonary hypertension usually directly affects the lung tissues and the functioning of cardiac structures, damaging the oxygenation mechanism of the body’s tissues.

Precisely for this reason, pulmonary hypertension in cats is considered as a complex syndrome and its effects are worrisome, since they can negatively affect practically all the organs that need to receive a correct oxygenation to guarantee their optimal functioning.

Symptoms of pulmonary hypertension in cats

Feline pulmonary hypertension encompasses several clinical manifestations, but the symptoms of pulmonary hypertension in more frequent cats are:

• Dyspnea of ​​effort: usually, it is characterized by lack of air and difficulty of recomposing when making any kind of effort. However, in more severe cases, shortness of breath may be permanent, even in a resting state.
• Constant exhaustion: felines with pulmonary hypertension can always be tired and show constant exhaustion. Due to the loss of respiratory capacity and tiredness, cats may lose interest in playing and doing daily activities, such as eating or drinking water. In more severe cases, the animal may also urinate and defecate out of the sandbox.
• Cough, which can be accompanied by blood in the most advanced stages of the disease.
• Intolerance to exercise.
• Fainting or syncopes.
• Loss of appetite and weight.
• Dehydration.
• Cardiac arrhythmia.
• Abnormal lung sounds (mainly in HP associated with respiratory diseases).

Here is a cat with pulmonary hypertension and polycythemia suffering from syncope, from @hockeyken10 on YouTube:

Causes and risk factors of pulmonary hypertension in cats

In human medicine, pulmonary hypertension can be idiopathic (also known previously as “primary”) or secondary, according to its etiology. Idiopathic conditions are those that appear “alone”, that is, that are not related to an underlying cause. However, idiopathic HP are rarely seen in the veterinary clinic.

Usually, pulmonary hypertension in cats develops from another disease, which is why it is usually considered as a symptom of a more complex clinical picture. Secondary HP is usually associated with various causes and can affect the arteries and pulmonary veins.

Although there is still no consensus in Veterinary Medicine on the classification of HP, the predominant tendency is to accept and adopt the same classification applied in humans. Next, we explain the main differences, the causes and pathophysiological processes of idiopathic and secondary HP in cats.

Idiopathic pulmonary hypertension in cats

In certain cases, the detailed diagnostic process is not able to reveal a cause specific for HP. When this happens, it is very likely that we are facing a case of idiopathic pulmonary arterial hypertension (previously also known as “primary”).

In idiopathic PAH, a dysfunction in the endothelium (walls of blood capillaries) of neuroendocrine origin that affects the vascular network of the lungs, leading to a predisposition to vasoconstriction and thrombosis. This picture begins in the small caliber pulmonary vessels, which are affected by the formation of small clots (thrombi). As a result, the loss of many pulmonary vessels and an elevation of vascular pressure in the lungs can be observed.

While there are many discussions about the possible causes of idiopathic PAH in felines, aging and obesity they appear as risk factors, since they favor the wearing down of cardiac and pulmonary vascular structures. Currently, research is also being carried out on the relevance of factor genetic in the predisposition to idiopathic HP in cats.

Secondary pulmonary hypertension in cats

According to the cause and the pathophysiological mechanism, secondary HP in cats is usually divided into 4 “types” main. Next, we summarize the main characteristics of each subtype of secondary pulmonary hypertension in cats:

• Secondary PAH related to pulmonary hypercirculation: in these cases, an increase in blood pressure inside the pulmonary arteries is observed, derived from a hypercirculatory picture. That is to say, the blood flow in the pulmonary arteries has a very high frequency and intensity, which increases the pressure inside these vascular structures. The most frequent causes are congenital heart diseases that cause deviations in the blood circulation, such as the patent ductus arteriosus (CAP) and the interatrial septum. In general, this type of PAH is diagnosed more commonly in young cats with malformations in the cardiovascular structure.
• Pulmonary hypertension derived from respiratory diseases: some respiratory pathologies can generate hypoxia and increase the risk of pulmonary vasoconstriction. As a consequence, the pulmonary vascular structure may suffer deformation and dysfunction, leading to an increase in pulmonary pressure. Secondary HP associated with chronic respiratory problems with hypoxia can also cause dilation and dysfunction in the right ventricle of the heart, a clinical picture that is known as cor pulmonale. Among the most frequent causes in cats, we find feline pneumonia, pulmonary fibrosis and obstructive tracheobronchial disease.
• HP associated with pulmonary thromboembolism: Thromboembolism is a complex clinical picture characterized by the formation of multiple clots (thrombi) in the vascular network of the lung (mainly in the pulmonary arteries) and on the right side of the heart. One of the consequences of pulmonary thromboembolism is the obstruction of the arteries and consequent persistent increase in pulmonary pressure. In general, heart dirofilariosis appears as the main cause of this type of HP. However, there are other possible causes, such as: systemic diseases that lead to hypercoagulability, neoplasms, glomerular disease, sepsis, hyperadrenocorticism, etc.
• HP causes alterations in the left atrium of the heart: When the left atrium presents a chronic elevation of pressure, drainage of the pulmonary veins is impaired. As a consequence, pulmonary venous hypertension, which is usually mild or moderate, can be observed. However, when this picture is added to respiratory diseases or thromboembolism, pulmonary hypertension can become severe. Among the main causes of this increase in blood pressure, we find dilated cardiomyopathy, congenital mitral dysplasia and a degenerative valvular disease (EVD) that most commonly affects the mitral valve.

Diagnosis of Pulmonary Hypertension in Cats

When observing any symptoms mentioned in your pussycat, do not hesitate to go quickly to the veterinary clinic. Pulmonary hypertension in cats requires a differential diagnosis very detailed to identify the underlying cause and subsequent specific treatment.

After performing a physical examination and analyzing the history of the patient, the veterinarian may request a electrocardiogram (ECG), some chest x-rays y clinical analysis (blood, urine, feces), to verify the state of health of the feline and to verify the evolution of the disease in his organism. In general, the suspicion of an HP should also be confirmed by a Doppler echocardiography.

Here is a color Doppler echocardiogram:

Treatment of feline pulmonary hypertension

The treatment of pulmonary hypertension in cats will depend on the identification of the underlying cause and the state of health of each patient. In general, the veterinarian adopts as basic therapy the controlled administration of some drugs with inhibitory action on pulmonary vasoconstriction. In addition, medications that contribute to strengthen the walls of pulmonary blood capillaries can also be used to slow the progression of endothelial dysfunction.

When the presence of clots (thrombi) is diagnosed, drug therapy is also usually added anticoagulants. On the other hand, in some cases of congenital cardiac malformations with deviations, surgical intervention may be studied as a viable treatment option for patients with a more stable state of health.

Is it possible to prevent pulmonary hypertension in cats?

The prevention of pulmonary hypertension consists fundamentally of offering adequate preventive medicine to the feline throughout its life. For this, it is essential to make periodic visits to the veterinarian every 6 months, respect the feline vaccination calendar and the deworming calendar in cats. It is also essential to offer a balanced diet of excellent quality to your pussycat, and provide toys, scrapers and other accessories that allow you to exercise your body and mind daily.

This article is merely informative, in .com we do not have the faculty to prescribe veterinary treatments or make any kind of diagnosis. We invite you to take your pet to the veterinarian in case of any type of condition or discomfort.

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