What is high blood pressure?
Arterial blood pressure refers to the pressure that blood exerts on the walls of the arteries when the heart contracts to send blood to the organs and when it relaxes to fill up again.
When the heart contracts, we speak of systole, and the "systolic pressure" corresponds to the maximum pressure prevailing at the level of the aorta and the large arteries during the ejection of blood by the left ventricle . In dogs, it is normally around 120 mmHg.
When the left ventricle relaxes, we speak of diastole, and the "diastolic pressure" thus designates the minimum pressure exerted against the walls of these same arteries during the relaxation phase of the left ventricle.In dogs, the normal diastolic pressure is around 85 mmHg.
We speak of high blood pressure in dogs in the event of a sustained rise in systolic pressure above 180 mmHg and/or diastolic pressure above 90 mmHg.
How is blood pressure measured in dogs?
There are several ways to measure a dog's blood pressure among:
- the direct and invasive method of catheterizing an artery,
- indirect non-invasive methods which include sphygmomanometry (installation of an inflatable cuff connected to a pressure gauge), the Doppler method or the oscillometric method.
Why can a dog suffer from high blood pressure?
Like humans, dogs can experience a temporary rise in blood pressure when under stress, such as during a visit to the vet. Once back to calm, we then observe a return to normal blood pressure.
But when elevated blood pressure is long-lasting, it may be a sign of an underlying disease such as:
- kidney disease: glomerulonephritis, amyloidosis, glomerulosclerosis, chronic interstitial nephritis, pyelonephritis, polycystic kidney disease, renal artery stenosis, renal infarction or even renal artery thromboembolism,
- an endocrine disorder such as hypercorticism, hypothyroidism, hyperestrogenism or even hyperaldosteronism,
- a rare tumor of the adrenal glands, called pheochromocytoma,
- cardiac hyperkinetic syndrome,
- etc.
It happens that a dog suffers from high blood pressure when no underlying disease is present or cannot be identified and we then speak of primary hypertension, idiopathic hypertension or even of essential hypertension.Some dog breeds like the Husky can be predisposed to it.
High blood pressure is more common in older dogs, also more often affected by kidney pathologies.
What are the signs of high blood pressure in dogs?
In a dog suffering from high blood pressure, we can observe:
- eye signs such as sudden blindness, retinal hemorrhage or detachment,
- neurological disorders such as seizures, staggering or uncoordinated movements called “ataxia”, partial paralysis, jerky eye movements called “nystagmus”, dizziness,
- heart trouble,
- other signs depending on the primary cause of arterial hypertension (example: blood in the urine or polyuro-polydipsia in case of associated kidney disease).
High blood pressure in dogs can be complicated by the appearance of coagulation disorders, heart failure or even nosebleeds called epistaxis.
How is hypertension treated in dogs?
Treatment for high blood pressure in dogs depends on the underlying cause, which the vet will work to determine.
In general, once the underlying disease is properly managed, treatment for high blood pressure is a low-s alt diet and drug therapy with diuretics, calcium channel blockers , beta-blockers and vasodilators.
The dog should be regularly monitored by the veterinarian to assess the effectiveness of the treatment and adapt it if necessary.