High blood Pressure in Cats - Symptoms, Causes and Treatment

When it comes to pulmonary hypertension in cats, we need to understand the way in which a cat’s lungs are affected. Feline lungs have a high capacity vascular network , but low pressure and resistance, which is directly involved in the process of respiration and oxygenation of tissues in its body. To establish a comparison, the resistance of the cardiac (systemic) vascular network can be 10 times higher than than that of 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 some diseases in cats, malformations or risk factors can cause an increase in the pressure and resistance of the pulmonary vascular structures. Therefore, pulmonary hypertension in cats usually directly affects lung tissue and the functioning of a cat’s cardiac structures, in turn, damaging the oxygenation mechanism of the body's tissues.

For this reason, pulmonary hypertension in cats is considered a complex syndrome. This syndrome is also worrisome, as it can negatively target and affect the bodies’ organs that need correct oxygenation to guarantee optimal functioning^[1]. If you think cat has high blood pressure, keep reading for more.

Feline pulmonary hypertension encompasses several clinical manifestations. The most common hypertension in cats symptoms include:

• Dyspnoea: characterized by difficulty or labored breathing. However, in more severe cases, shortness of breath may be permanent.
• Constant exhaustion: felines suffering from pulmonary hypertension can be very tired and present constant exhaustion. Because of the loss of respiratory capacity and fatigue, cats may lose interest in playing and doing habitual 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 more advanced stages of the disease.
• Cat Intolerance to exercise.
• Syncopes. (fainting)
• Loss of appetite and weight.
• Cat dehydration.
• Cardiac arrhythmia.
• Abnormal pulmonary sounds (mainly in HP associated with respiratory diseases).

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

In general, pulmonary hypertension in cats develops from other cat diseases, which is why it is usually considered as a symptom derived from a more complex clinical case. 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 of HP classification, the prevailing tendency is to accept and adopt the same classification which is applied to humans.

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

In idiopathic PAH, there is a dysfunction in the endothelium (walls of blood capillaries) of neuroendocrines that affects the vascular network of the lungs, leading to a predisposition to vasoconstriction and thrombosis. This case begins in the small-sized pulmonary vessels, which are affected by the formation of small clots (thrombi). As a consequence, there is a loss of pulmonary vessels and and an elevation of vascular pressure in the lungs.

Although there are many discussions about the possible causes of idiopathic PAH in felines, cat aging and obesity in cats appear as prominent risk factors, since they favor the wearing down of cardiac and pulmonary vascular structures. Currently, the relevance of the genetic factor in the predisposition to idiopathic PH in cats is also being investigated as a cause. For more, we recommend taking a look at our article about: Obesity in cats.

According to the cause and the pathophysiological mechanism, secondary HP in cats is usually divided into 4 main "types". The characteristics of each sub-type of secondary pulmonary hypertension in cats is summarized by:

• Secondary PAH related to pulmonary hypercirculation in cats: in these cases, there is an increase in blood pressure inside the pulmonary arteries, derived from hypercirculation. Where 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 of this are congenital heart diseases that cause deviations in blood circulation, such as the persistent ductus arteriosus (CAP) and the interatrial septum. In general, this type of PAH is diagnosed more commonly in younger cats with malformations in the cardiovascular structure.

• Pulmonary hypertension derived from respiratory diseases in cats: some respiratory diseases in cats can generate hypoxia and increase the risk of pulmonary vasoconstriction. As a consequence, the pulmonary vascular structure may suffer deformation and dysfunction, which can lead 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 case that is known as cor pulmonale. Among the most frequent causes in cats are feline pneumonia, pulmonary fibrosis and obstructive tracheobronchial disease. For more, we recommend taking a look at: Pneumonia in cats.

• Hypertension in cats associated with pulmonary thromboembolism: thromboembolism is a complex clinical case 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 a consequent persistent increase in pulmonary pressure. In general, there will be an appearance of heart dirofilariasis which can be a main cause of this type of HP. However, there are other possible causes, such as: systemic diseases that can lead to hypercoagulability, neoplasms, glomerular disease, sepsis, hyperadrenocorticism, etc.

• HP in cats causes alterations in the left atrium of the heart: when the left atrium presents a chronic elevation of pressure, drainage of the pulmonary veins can be impaired. As a consequence, pulmonary venous hypertension, which is usually mild or moderate, will be noticed. However, when this case is added to respiratory diseases or thromboembolism, pulmonary hypertension can become severe. Among the main causes of this increase in blood pressure are; dilated cardiomyopathy, congenital mitral dysplasia and degenerative valvular disease (EVD) that most commonly affects the mitral valve.

If you notice any of these mentioned symptoms in your cat, do not hesitate to go the veterinary clinic immediately. Pulmonary hypertension in cats requires a very detailed diagnosis to identify its underlying cause, in order to apply the appropriate treatment.

After performing a physical examination and analyzing the history of the animal, a veterinarian may request an electrocardiogram (ECG), chest x-rays and/or a clinical analysis (blood, urine, feces). They may also use a cat high blood pressure monitor to check your cat’s blood pressure levels. These tests aid to verify your cat’s health status as well as the evolution of the disease in its body. In general, any suspicion of HP should be confirmed by Doppler echocardiography. For more, we recommend reading our article were we discuss everything you need to know about systemic arterial hypertension in cats.

So, my cat has high blood pressure, what do I do? Treatment of pulmonary hypertension in cats will depend on identifying the underlying cause. In general, a veterinarian will adopt administer some drugs which aim to inhibit action on pulmonary vasoconstriction. In addition, a veterinarian might prescribe medications that contribute to strengthening of the walls of the pulmonary blood capillaries which can also be used to slow down the progression of an endothelial dysfunction.

If the presence of clots (thrombi) is confirmed, your cat may be prescribe anticoagulant drug treatment. In some cases of congenital cardiac malformations, surgical intervention may be considered as a viable treatment option for cats who are considered more stable.

Through the use of adequate preventative medicine high blood pressure in cats can be avoided. It is essential visit a veterinarian every 6 months for check ups. This is in addition to respecting your cat’s vaccination and deworming schedule. It is also essential to offer your cat an excellent quality balanced diet . In addition, do not forget to provide your cat with toys, scrapers and other accessories that allow them to exercise their bodies and minds daily.

For more about cat entertainment, we recommend reading our following articles:

• Toys for cats: ideas and tips to play with your cat.
• 10 games to entertain my cat.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

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