Causes of Canine Hypertension
Blood pressure is regulated by a highly integrated and complex system of connections between the central and peripheral nervous systems. The central nervous system is made up of the brain and spinal cord. The peripheral nervous system contains the nerves and some other nervous system tissue that are located outside of the brain and spinal cord. The kidneys, and of course the heart tissues, are very involved with the regulation of blood pressure.
Hypertension can be primary or secondary to another condition. Primary hypertension - also referred to as essential or idiopathic hypertension - is high blood pressure that is not caused by or directly related to another disease process. The causes of primary hypertension in dogs are not known. However, some research indicates that this form of canine hypertension may have a genetic component, although the precise mode of inheritance and the extent of hereditary involvement are not well understood. This data is largely derived from the results of breeding dogs with primary hypertension to one another and then assessing the health of the resulting offspring.
Secondary hypertension is high blood pressure that is caused by or derived from another medical condition or disorder. It accounts for almost all of the cases of hypertension seen by veterinarians today. Secondary hypertension in dogs can be caused by many different things. Advanced renal (kidney) disease, such as end-stage kidney failure, glomerulonephritis, amyloidosis or renal arterial stenosis, can lead to high blood pressure. Hypertension also can be secondary to hyperthyroidism or hyperadrenocorticism (commonly called Cushing’s Disease). Other possible causes of secondary hypertension are diseases of the endocrine glands (endocrine hypertension), eyes (ocular hypertension due to persistently elevated blood pressure within the globe of the eye, which is called intraocular pressure), liver (portal hypertension caused by some impedance of blood flow through a damaged or diseased liver or portal vein) or lungs (pulmonary hypertension that results from the abnormally high pressure of blood flowing through the lungs or through the left chambers of the heart, which supply blood to the lungs).
Certain drugs that cause blood vessels to constrict, or to become narrowed or squeezed (vasoconstriction), have been associated with secondary hypertension in dogs. Incidents of acute and severe pain, stress or anxiety, which can be caused by any number of things, may also contribute to high blood pressure. Uncommonly, dogs with diabetes mellitus develop concurrent secondary hypertension. Some authorities suggest that a diet high in sodium (salt) can contribute to high blood pressure in domestic animals.
A detailed description of all of the potential causes of canine secondary hypertension is beyond the scope of this particular article. Each of those possible causes is a unique and separate disease or disorder, many of which may be addressed elsewhere on this website.
There is no current way to prevent primary hypertension in domestic dogs. Secondary hypertension may be able to be prevented, managed or potentially cured by taking the steps necessary to prevent, manage or treat the underlying cause of the condition.
A dog’s attending veterinarian is in the best position to discuss the possible causes of hypertension with its owner.