Not hypertrophic cardiomyopathy: decreased cardiac output
Hyperaldosteronism due to an adrenal tumor.
Minor diseases (probably not a cause in cats)
Anemia, Cushing's disease, pheochromocytomas
Incidence: JAAHA, 11/94
65% of cats with chronic renal disease
23% of cats with hyperthyroidism
Clinical signs
Sudden onset retinal blindness
Encephalopathy: seizures, strokes, vocalization
Cardiac (working against increased arterial pressure): systolic murmurs, gallop rhythms
Biting at back or flanks – hyperesthesia
Workup for a blind cat
Check blood pressure, if possible
History like renal or thyroid disease: WL, PU, PD, PP
Exam findings of: small kidneys or enlarged thyroid
Lab findings of: elevated T4 or creatinine
Plasma aldosterone concentration ($12.00); Available from Diagnostic Center for Population and Animal Health, Michigan State University, (517) 353-0621. Submission forms can be downloaded at www.animalhealth.msu.edu. (Fee as of 9-05.)
Continue to recheck q48h until the BP is below 150 mmHg.
If the BP is not < 150 on the third visit (2nd recheck), add benazepril.
If the cat has renal disease, you need it anyway.
Step Two: Diagnose and treat the underlying disease
See above: Workup for a blind cat
Hyperthyroidism: When controlled, BP normalizes and further treatment is not needed.
Renal Disease: Must be treated long-term due to interaction of HT and renal disease.
Step Three: Diet
JVIM: May/June 2007 ACVIM Consensus Statement
“Although frequently recommended as an initial step in the pharmacological management of high BP, dietary salt restriction is controversial, and the available evidence suggests that substantial sodium restriction alone generally does not reduce BP. In fact, sodium restriction activates the renin-angiotensin-aldosterone axis and may actually increase BP in certain settings. Currently, … the panel recommends avoiding high dietary sodium chloride intake in hypertensive animals but does not recommend that a specific effort be made solely to restrict dietary sodium chloride intake. Until more data is available, the selection of appropriate diet should be based on other patient-specific factors, such as underlying or concurrent diseases and palatability.”
Alternative blood pressure monitors
Syringe & needle: easiest blood sample you ever took from the cephalic vein.
Stethoscope: hyperthyroid cats often have pounding heartbeats
Lead II ECG: hyperthyroid cats have tall waves (or deep S waves) and tachycardia.
Palpate for bounding pulse.
Another sign of hypertension
Aortic undulation
Most dramatically seen on a lateral view of the chest.
More often seen on a VD or DV as the aortic knob.
Measuring blood pressure
Avoid the “white coat effect” JVIM, 3/99, p. 134-142.
Quite room
No odor, sounds, or sight of dogs
Owner present
Get the cat comfortable
Clinically feasible BP units are indirect since intra-arterial catheters are not practical.
Doppler: Vet-Dopp by Vmed/DVM Solutions: 1-866-373-9627
Oscillometric: Cardell and petMAP
High Definition Oscillometric: Vmed/DVM Solutions: 1-866-373-9627
The unit I am currently using.
It allows you to evaluate the reliability of each measurement as it is being recorded.
Number of measurements
Do not do too often due to arterial fatigue.
I take two reliable (see above) readings and average them.
Measure blood pressure in the following situations
Geriatric profiles
Surgical monitor (Doppler)
Suspected saddle thrombus
Concern about proper circulation to leg or tail due to trauma
Chronic renal disease
Hyperthyroidism
Murmur or gallop rhythm
Hyphema
Sudden onset blindness if retinal hemorrhage or detachment is present