A retrospective study described systemic hypertension (SHT) in dogs with acute kidney injury (AKI) and the efficacy of amlodipine besylate for its treatment. Fifty-two client-owned dogs with naturally occurring AKI were divided into 2 groups: those treated with amlodipine (n = 22) and those not treated with amlodipine (n = 30). Systolic systemic blood pressure (SBP) ≥160 mm Hg was defined as SHT and systolic SBP ≥180 mm Hg as severe SHT. Amlodipine was administered in increments of 0.25 mg/kg Q 1-3 H until a goal systolic SBP of 140 to 160 mm Hg was reached or up to a maximal cumulative dose of
1 mg/kg Q 24 H. Subsequent doses were based on the cumulative 24-hour dose necessary to achieve initial control and on individual clinical response to maintain the target SBP. Dogs reaching this target were considered responders, independent of the absolute change in SBP. Partial responders were dogs with decreases in systolic SBP of ≥20 mm Hg but failure to reach the goal SBP. Dogs with decreases of SBP <20 mm Hg that did not reach the target despite maximal daily dose of amlodipine were considered nonresponders. Amlodipine therapy resulted in a decreased systolic SBP of 24 mm Hg (12–34) and correction of severe SHT in 10 of 11 dogs within 24 hours. Further prospective controlled studies are necessary to confirm efficacy, evaluate potential negative effects of treatment on renal function, and refine treatment recommendations.

Commentary: This retrospective study is the first to describe the occurrence of SHT in dogs with AKI. At initial evaluation, 37% of 52 dogs were hypertensive and 15% were severely hypertensive. These percentages interestingly increased to 81% and 62%, respectively, during the period of hospitalization. The authors postulated that this increase could have been associated with progression of renal lesions and decreased ability to control SBP, fluid therapy and/or solute overload, and stress and/or pain resulting in adrenergic stimulation. Amlodipine treatment in 22 of the dogs resulted in significant rapid decrease in SBP with a response rate of 91% by 48 hours. Despite the SBP lowering efficacy, the amlodipine-treated group had a higher mortality (41% versus 17% in nontreated dogs). The higher mortality was likely associated with more severe renal injury in the amlodipine-treated group but this could not be confirmed. Routine recommendations regarding amlodipine use in dogs with SHT associated with AKI cannot be made without further study.—Gregory F. Grauer, DVM, MS, Diplomate ACVIM

Occurrence of systemic hypertension in dogs with acute kidney injury and treatment with amlodipine besylate. Geigy CA, Schweighauser A, Doherr M, Francey T. J SMALL ANIM PRACT 52:340-346, 2011.