Hypertension, Feline - contd.
The diagnosis is made by documenting elevated readings during blood pressure measurement. The normal range for blood pressure in cats is up to 180 to 200 mm Hg for systolic readings; systolic refers to the phase of the heart's cycle characterized by contraction of the ventricles. For diastolic readings, which measure ventricular filling, the normal range is 100 to 110 mm Hg. Since stress associated with blood pressure measurement can elevate readings above this range even in normal cats, the results must be interpreted in light of the individual cat's situation. Measuring blood pressure in a quiet, calm environment is important, because allowing cats to become acclimated to their surroundings will help eliminate some of the "white coat syndrome." A diagnosis of hypertension is more plausible if the cat has symptoms that are common with disorders known to be associated with hypertension, if such disorders have already been diagnosed, or if signs such as bleeding in the eyes, retinal detachment, blindness, or severe neurological abnormalities are present.
Once the diagnosis is established, other pieces of information are important in assessing feline hypertension. A complete blood count, chemistry profile, urinalysis, and thyroid hormone level will detect evidence of kidney failure, hyperthyroidism, and other complicating disorders. X-rays of the chest and abdomen should be obtained to screen for obvious structural disorders such as tumors, abnormalities of kidney shape or size, and heart enlargement. Ultrasound examination of the abdomen may be used if abnormalities are suspected, and an ultrasound of the heart, or echocardiogram, may be necessary if the cat has a heart murmur or if changes appear in the chest x-rays. Since many cats with hypertension have heart murmurs, echocardiography is used frequently to assess for changes in the heart secondary to hypertension and for other structural heart muscle or valve disorders that are common in older cats.
