Systemic Hypertension Flashcards
According to the Doppler study, what is the normal blood pressure for a cat?
120-160mmHg
According to the Doppler study, what is the normal blood pressure for a dog and what is the exception to this rule?
140-150mmHg is normal
Sighthounds and Brachycephalic breeds have a slightly higher SBP (10-20mmHg higher)
What SBP carries severe risk of target organ damage?
> 180 mmHg is severely hypertensive and has severe risk of organ damage
What structures can target organ damage affect? (4)
Eye
CNS
Cardiovascular system
Kidney
Target organ damage in the eye due to hypertension is identified in what percentage of cats?
And can this be reversed?
60-100% of cats
57.6% of cats regain vision with treatment
What target organ damage may we expect to see in the heart due to hypertension? (3)
Left ventricular hypertrophy
Murmurs
Gallop heart sounds
When would we expect to see CNS target organ damage?
in Acute SBP changes (less common in chronic hypertension)
Would we expect to see kidney damage in cases of mild hypertension?
Why?
NO- kidney has the capacity for autoregulation which controls renal blood flow and pressure at the glomerulus- this works with SBP of up to 160mmHg
What happens to the kidney when systolic blood pressure exceeds 160mmHg?
Autoregulation stops > increased pressures are transferred to the glomerular capillaries > this damages the glomerulus and causes proteinuria
What are the three types of Hypertension seen in Veterinary Practice?
Idiopathic Hypertension
Situational Hypertension (aka white coat)
Secondary Hypertension
What is white coat hypertension?
increase in blood pressure due to the physiological response to clinic
What drugs can predispose an animal to secondary hypertension?
Give 3.
Glucocorticoids
Mineralcorticoids
Erythrocyte stimulating agents such as erythropoietin
Epinephrine
Toceranib
What are the most common blood pressure monitoring devices used in clinic?
Doppler and High Definition Oscillometric Device
When measuring blood pressure what position should the animal ideally be in?
Lateral Recumbency
(don’t force it though!)
When measuring blood pressure, the cuff size should be…
30-40% of the animals limb circumference
How many readings of SBP do we take?
5-7 readings during one session- discard the first reading and take an average of the rest to get a mean SBP
When is a blood pressure measurement indicated? (5)
- Concern that patient presents with target organ damage
- Patient has been diagnosed with a condition that causes hypertension
- Patient is receiving a drug that can be associated with secondary hypertension
- Patient is of a certain criteria for screening e.g. cats over 9 years old
- Patients already diagnosed with hypertension
When do we diagnose and treat hypertension?
When SBP is above 160mmHg AND there is evidence of target organ damage OR evidence of concurrent disease
What two drugs are licensed to treat hypertension in cats?
Amlodipine (first line) & Telmisartan
How does Amlodopine work?
Calcium channel blocker- causes AFFERENT arterial dilation to decrease glomerular capillary pressures
How does Telmisartan work?
Angiotensin receptor blocker- inhibits the vasoconstrictory actions of Angiotensin II on the EFFERENT arteriole to decrease GFR
What is the maximum dose of Amlodipine you can give to a cat in the treatment of Hypertension?
Maximum 1.25mg/cat (this is off license!) and rare to need this dose
What do we do if treating a cat with Amlodipine doesn’t work?
Use a combination of Amlodipine and an Angiotensin receptor blocker such as Telmisartan
[just ensure you don’t overcompensate and cause hypo tension]
What products are licensed to treat Hypertension in dogs?
NONE!- need to prescribe Telmisartan or a Calcium channel blocker through the cascade
