Hypertension in dogs appears to be more resistant to drug therapy. Because ACE inhibitors reduce intraglomerular pressure
even when systemic blood pressure is not effectively ameliorated, these drugs have a therapeutic advantage as first-line drugs
in dogs with chronic kidney disease in mitigating the renal effects of hypertension. However, since ACE inhibitors are often
relatively ineffective antihypertensive drugs in dogs, amlodipine is typically combined with ACE inhibitor therapy to achieve
the therapeutic goal. The initial dose for an ACE inhibitor is 0.25 to 0.5 mg/kg with monitoring of the serum creatinine concentration
response (the dose may be cautiously increased to 3 mg/kg). The dose range for amlodipine is 0.1 to 0.6 mg/kg as needed to
achieve the therapeutic goal.
Reassess patients receiving antihypertensive therapy every week or two until the treatment target (systolic blood pressure
< 150 mm Hg) has been achieved. Thereafter, monitor blood pressure every three to four months.
#11 Provide calcitriol in dogs. Calcitriol is indicated in dogs with chronic kidney disease stages 3 and 4 to slow the progression of the disease and extend
survival (evidence grade 1).18 However, do not begin calcitriol therapy until the patient's serum phosphorus concentration is 6 mg/dl or less. Unfortunately,
evidence for or against calcitriol therapy in cats with chronic kidney disease is weak.
Calcitriol may be administered initially at a dose of 2.5 ng/kg/day. Monitor ionized calcium and parathyroid hormone (PTH)
concentrations weekly until a treatment endpoint is reached. The dose of calcitriol may be adjusted to achieve a treatment
endpoint of normalizing PTH concentrations without inducing hypercalcemia. Increase calcitriol doses about 0.75 to 1 ng/kg
as needed to a maximum dose of 5 ng/kg. If hypercalcemia develops before PTH concentrations decline to normal, the dosage
of calcitriol must be reduced to prevent adverse effects of hypercalcemia. An alternate approach is to attempt to provide
two or three days total dose of calcitriol every second or third day. This dosage may mitigate the hypercalcemia and increase
the effect on PTH concentrations.
Patients receiving calcitriol should have their serum calcium, ionized calcium, and phosphorus concentrations monitored at
least every two to three months.
Dr. Polzin has received research sponsorship and speaking honoraria from Hill's Pet Nutrition, Royal Canin, and Nestlé Purina;
receives support for IRIS from Novartis; and has consulted for and received honoraria from Bayer, Pfizer, and Vétoquinol.
David J. Polzin, DVM, PhD, DACVIM (small animal internal medicine)
Department of Veterinary Clinical Sciences
College of Veterinary Medicine
The University of Minnesota
St. Paul, MN 55108
Dr. Polzin lectured on this topic at the 2007 CVC Central, and this article is adapted from the conference proceedings.
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