Page 247 - Small Animal Internal Medicine, 6th Edition

CHAPTER 11 Systemic Arterial Hypertension 219

Oral amlodipine can be effective in quickly decreasing BP, Chetboul V, et al. Comparison of Doppler ultrasonography and
especially in cats, and has less risk of inducing hypotension high-definition oscillometry for blood pressure measurements in
VetBooks.ir than more potent vasodilators. Oral amlodipine is initiated Coleman AE, et al. Attenuation of the pressor response to exoge-
healthy awake dogs. Am J Vet Res. 2010;71:766–772.
at the typical dose of 0.625 mg/cat, and BP rechecked q2h.
nous angiotensin by angiotensin-receptor blockers in normal
Maximal effect of amlodipine after a single oral dose in cats
dogs [abstract]. J Vet Intern Med. 2014;28:977.
occurs at 4 to 6 hours. If BP is not adequately controlled in Elliot J, et al. Feline hypertension: clinical findings and response to
4 to 6 hours, an additional 0.625 mg/cat PO can be given, antihypertensive treatment in 30 cases. J Small Anim Pract.
and dose continued q12h. 2001;42:122–129.
Direct-acting vasodilator agents (e.g., nitroprusside, Finco DR. Association of systemic hypertension with renal injury
hydralazine) can produce faster reduction in BP; arterial in dogs with induced renal failure. J Vet Intern Med. 2004;18:
pressure should be closely monitored to prevent hypoten- 289–294.
sion. Nitroprusside is dosed to effect by constant intravenous Hanzlicek AS, Baumwart RD, Payton ME. Systolic arterial blood
(IV) infusion (see Table 11.1). Hydralazine (IV or PO) is an pressure estimated by mitral regurgitation velocity, high defini-
alternative, especially for dogs. An IV β-blocker (esmolol, tion oscillometry, and Doppler ultrasonography in dogs with
propranolol) or acepromazine (see Table 11.1) can also be naturally occurring degenerative mitral valve disease. J Vet
Cardiol. 2016;18:226–233.
used. One of these agents can be added to oral amlodipine Henik RA, Stepien RL, Bortnowski HB. Spectrum of M-mode
therapy if BP is not adequately reduced within 12 hours. BP echocardiographic abnormalities in 75 cats with systemic hyper-
rechecks within 1 to 3 days are recommended in patients tension. J Am Anim Hosp Assoc. 2004;40:359–363.
with serious or rapidly progressive signs. Henik RA, et al. Efficacy of atenolol as a single antihyperten-
When a hypertensive crisis is related to pheochromocy- sive agent in hyperthyroid cats. J Feline Med Surg. 2008;10:
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phentolamine can be used intravenously (see Table 11.1) and Huhtinen M, et al. Randomized placebo-controlled clinical trial of
titrated to effect. Addition of a β-blocker can help mitigate a chewable formulation of amlodipine for the treatment of
pheochromocytoma-induced tachyarrhythmias, but it hypertension in client-owned cats. J Vet Intern Med. 2015;29:
should not be administered alone or before an α-blocker is 786–793.
given, for reasons previously discussed. Antihypertensive Jackson BL, Adin DB, Lehmkuhl LB. Effect of atenolol on heart rate,
treatment is recommended for 2 to 3 weeks before surgery arrhythmias, blood pressure, and dynamic left ventricular
outflow tract obstruction in cats with subclinical hypertrophic
for pheochromocytoma excision, if possible. For inoperable cardiomyopathy. J Vet Cardiol. 2015;17:S296–S305.
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Suggested Readings Jenkins TL, et al. Attenuation of the pressor response to exogenous
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