FELINE MEDICINE
High blood pressure
Amlodipine is the most effective drug for high blood
pressure in cats. But don’t use it unless there’s
direct evidence of target organ damage, says Dr.
St. Denis. Clinicians should also be certain the cat
is hypertensive, following recommendations from
the International Society of Feline Medicine (ISFM)
guidelines for managing hypertension. She starts
with 0.625 mg every 24 hours and reassesses in three
to five days, and if blood pressure is higher than 160
mm Hg, she increases the dosage by 0.5 mg/kg/day.
She maxes out amlodipine dosages at 2.5 mg/cat.
Monitor blood pressure every three to four months.
If amlodipine is not controlling blood pressure, first
check adherence with the client. If everything checks
out and you’ve maxed out your amlodipine dosage,
Dr. St. Denis recommends adding in telmisartan
(Semintra), a new angiotensin receptor blocker from
Boehringer Ingelheim. Anecdotally, Dr. St. Denis finds
it is a nice adjunct to amlodipine administration in
uncontrolled hypertensive cases.
What to do about phosphorus and calcium
concentrations
Therapeutic kidney diets are the first line of
defense against abnormal calcium and phosphorus
concentrations. If you find that phosphorus is still
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increasing or unacceptably high even if a cat is on
a therapeutic diet, then a phosphate binder, such as
aluminum hydroxide, is in order, Dr. St. Denis says.
She advises avoiding any aluminum hydroxide
products that contain calcium, splitting the daily dose,
and giving with food because phosphate binders bind
to phosphate in food.
Renal secondary hyperparathyroidism is due to
deficiency of calcitriol, which causes calcium
dysregulation and increased ionized blood calcium
in the bloodstream. If you notice hypercalcemia, it’s
important to measure parathyroid hormone (PTH) and
ionized calcium concentrations. If the PTH is normal
or low, then hypercalcaemia is not due to renal
secondary hyperparathyroidism.
If you elect to prescribe calcitriol to manage calcium
concentrations, Dr. St. Denis says to give twice weekly,
ensure that phosphorus concentrations are less than
6 mg/dl in the blood, and monitor regularly. Check
ionized calcium and PTH concentrations every four to
six weeks until they normalize, then check them every
three to six months, depending on what your client is
willing to do.
Reference available online