High Blood Pressure in Your Pet
High blood pressure (also known as hypertension) in cats or dogs is generally caused by an underlying disease. It is becoming diagnosed more frequently now that veterinarians have begun to routinely monitor blood pressure. One study found that 65% of cats with hyperthyroidism had mild hypertension, while a study of clinically normal dogs showed hypertension in 10% of the patients.
Dogs and cats that are diagnosed with high blood pressure are typically brought into their veterinarian for sudden blindness, blood seen within the chamber of the eye, dilated pupils, blood in the urine, bloody nose, seizures, disorientation, circling, or even routine examinations. Upon examination by the veterinarian, retinal detachment, shrunken kidneys, nystagmus (twitching of pupils), heart murmurs, and a palpable thyroid gland may be noted. A blood pressure may be taken at that time using a Doppler machine much similar to those used in human medicine. An inflatable cuff is placed around one of the animals' rear limbs and the cuff is inflated to determine the systolic, diastolic, and mean blood pressure. The heart rate is calculated at that time as well. Generally three to four readings are performed to determine the most reliable measurement. It is important for the animal to maintain a low excitement level while the measurements are being performed. Hypertension is currently diagnosed by the following values:
Dog: Systolic > 180mm Hg; Diastolic > 100mm Hg
Cat: Systolic > 170-180 mm Hg; Diastolic > 120 mm Hg
To determine the underlying disease causing the hypertension, several diagnostic tests may be recommended. Complete blood counts are generally normal, however blood chemistry panels and urinalysis can help rule out kidney disease, diabetes mellitus, hyperadrenocorticism (Cushing's), and electrolyte imbalances. Thoracic radiographs may be needed to evaluate changes as well as size of the heart when a murmur is noted. Abdominal radiographs and/or ultrasound may be needed to evaluate the liver, adrenals, and kidneys.
Once an underlying problem has been determined and it is one which is curable or controlled, hypertension may be managed by medications and sodium restricted diets. The blood pressure should be monitored weekly until it is under control, while laboratory tests to measure the clinical disease response and side effects of medications should be monitored on a routine basis as determined by your veterinarian.