Systemic Hypertension

Description:

• Hypertension is defined as the pathological elevation of arterial blood pressure.

• There are two main types of hypertension, systemic hypertension (affects the systemic circulation) and pulmonary hypertension (affects the pulmonary circulation).

• Blood pressure in veterinary patients is not measured routinely; therefore hypertension is usually only diagnosed after clinical signs become apparent.

Systemic Hypertension

• Primary systemic hypertension= idiopathic increase in arterial blood pressure

• Secondary systemic hypertension=increase in arterial blood pressure secondary to a pathological process

• The ocular system, cardiovascular system, and nervous system are the most vulnerable to elevated arterial blood pressures. However, some endocrine disturbances have also been found to predispose animals to hypertension.

Signalment

Dogs: male>female; obese animals; middle to old age

Cats: middle to old age

Diagnosis

History & Clinical Signs

• Signs are the result of ischemia, edema, and/or haemorrhage of the affected areas

Neurological Signs

-Depression

-Seizures

-Syncope

-Paresis

-Vestibular Signs

-Ataxia

Cardiac Signs

-Left Ventricular Hypertrophy

-Heart Failure

-Systolic Murmur

-Gallop rhythm

Ocular Signs

• In cats, ocular abnormalities from hypertension are usually the first thing detected.

-Blindness

Fundic Examination

-Hyphemia (Blood in the anterior chamber)

-Retinal Haemorrhage

-Retinal Detachment

-Retinal Degeneration

Renal Signs

• Renal disease can both be caused by hypertension and cause hypertension.

• Chronic renal failure is the most common cause of hypertension showing clinical signs in dogs and cats.

-Renal Disease (especially glomerular damage)

• Glomerular damage allows protein leakage, therefore animals with hypertension are more proteinuric than unaffected animals

Endocrine Signs

-Hyperthyroidism (cats)

-Hyperadrenocorticism, Diabetes Mellitus (dogs)

Physical Exam

Blood Pressure Measurement

• Systolic Pressure> 175 indicates hypertension in a relaxed dog or cat

• Diastolic Pressure> 100 indicates hypertension in a relaxed dog or cat

1. Direct Blood Pressure Measurement (Invasive)

• Uses an indwelling arterial catheter

-Measures systolic, diastolic, and mean arterial pressures

-Used on very ill patients or those undergoing anaesthesia

2. Indirect Blood Pressure Measurement (Non-invasive)

• Two types that measure systolic arterial pressure

-Doppler Flow Technique: good for large dogs, poor for cats

-Oscillometric Technique: good for small dogs, good for cats

Treatment

Cats

• Treat the underlying problems

• Calcium Channel Blocker (e.g. amlodipine)

• Monitor Blood Pressure

Dogs

• Treat the underlying problems

• Monitor Blood Pressure

Dogs with Renal Disease:

• ACE-inhibitor (e.g. enalopril): Given alone or in combination with some of the other treatments listed below.

• Calcium Channel Blocker (e.g. amlodipine)

• Sodium Restricted Diet

• Beta Blockers (e.g. atenolol)

• Diuretics (e.g furosemide)

• Vasodilators (e.g. enalopril)

Prognosis

-Cats with hypertension are more successfully treated than dogs.