Systemic Hypertension in Dogs
What is “blood pressure” and how is it measured?
Blood pressure refers to the pressure against the walls of arteries during the time the heart contracts and empties itself of blood as well as during the time the heart relaxes and fills with blood.
When the heart contracts, this is known as systole, and the “systolic pressure” is the maximum pressure against the walls of the arteries. When the heart relaxes, it is known as diastole, and “diastolic pressure” is the minimum pressure against the walls of the arteries.
“Systemic hypertension” describes high blood pressure throughout the entire body, and this means a sustained elevation in systolic pressure of 140mmHg or greater, in diastolic pressure of 90mmHg or greater, or both.
My 10 year-old dog has been diagnosed with systemic hypertension (high blood pressure). Is this like hypertension in people?
Like people, dogs can experience temporary elevations in blood pressure due to stress effects – for example, just being in a veterinary hospital. It is important to take several readings and to create as quiet an environment as possible. Hypertension in dogs is often due to an underlying disease and when this is the case, it is called “secondary hypertension.” If no underlying disease is present or can be identified, then it is called “primary hypertension.”
Hypertension is more common in older dogs, consistent with the development of underlying disease such as chronic kidney disease, or excessive levels of steroids produced by the adrenal glands in dogs with Cushing's syndrome. Younger dogs may develop hypertension if they have kidney disease due to infection (such as leptospirosis) or a developmental kidney abnormality.
What are the signs of hypertension?
There are some signs of hypertension that can be observed. These include:
- Sudden blindness, bleeding inside the globe of the eye, and persistently dilated pupils
- Detached retinas
- Nervous system signs like depression, head tilt, seizures, disorientation, wobbly or uncoordinated movements (called “ataxia”), circling, weakness or partial paralysis, or short, rapid, back-and-forth movements of the eyes (called “nystagmus”)
- Increased drinking and urinating with the progression of chronic kidney disease
- Blood in the urine (called “hematuria”)
- Bleeding in the nose and nasal passages (known as “epistaxis” or nosebleed)
- Heart murmurs or abnormal heart rhythms
What causes hypertension in dogs?
The cause of primary hypertension is unknown. Secondary hypertension accounts for a majority of hypertension in dogs, and can be attributed to kidney disease, adrenal gland disease, diabetes mellitus (less common), pheochromocytoma (adrenal gland tumor and very uncommon), or central nervous system disease (very rare).
How is hypertension typically treated in dogs?
The treatment of dogs with hypertension depends upon the underlying cause, if there is one. If the dog develops a serious complication related to hypertension like acute kidney failure or bleeding into the eye, there may be a need for hospitalization. In general, once any underlying condition is appropriately managed, medication and nutrition are important to normalizing blood pressure.
Medications that are commonly used to manage hypertension in dogs include angiotension converting enzyme (ACE) inhibitors and calcium channel blockers. Additional medications may be required depending upon the response to initial therapy. Therapeutic nutrition is generally accepted as an important part of long-term management.
What kind of monitoring will be required for my dog?
The treatment goal for a dog with hypertension is a systolic pressure of 140mmHg or less, and a diastolic pressure of 90mmHg or less. Periodic laboratory testing will be required to monitor for side effects of medication and progression of disease.
Potential complications of hypertension in the dog include:
- Congestive heart failure
- Chronic kidney disease
- Retinal degeneration and subsequent blindness
- Bleeding into the eye
- Stroke (cerebral vascular accident)
What can I expect for my dog’s long-term outlook?
The course of canine hypertension depends on the underlying cause. When blood pressure is well managed, the risks for potential complications are minimized. Medication for hypertension is generally a lifetime undertaking, and may be adjusted over time as needed.
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