Felis ISSN 2398-2950

Hypertension

Contributor(s): Serena Brownlie, Philip K Nicholls, Mark Rishniw, Penny Watson, Esther Bijsmans

Introduction

  • Consistent increase in arterial blood pressure above the species normal.
  • Cause: usually secondary, eg chronic renal failure, hyperthyroidism (23-87% of cases); primary (idiopathic) cases have been reported.
  • Diagnosis: probably underdiagnosed in veterinary medicine.
  • Treatment: address underlying cause, treat hypertension with amlodipine besylate.
  • Prognosis: early screening and identification important to prevent organ damage (particularly eyes, central nervous system, heart and kidney).
    Print the owner factsheet on hypertension  Hypertension to give to your client.
Follow the diagnostic tree for Hypertension Hypertension.

Pathogenesis

Etiology

Primary (idiopathic)

  • Rare; one colony in USA: familial hypertension.
  • 13-20% of hypertensive cats have no evidence of overt azotemia Azotemia or other underlying disease and could have idiopathic hypertension. However, some do  have reduced urine concentrating ability and may have non-azotemic CKD, and a complete work-up including abdominal ultrasound and aldosterone measurements was not always performed.

Secondary

  • Renal disease Kidney: chronic kidney disease (up to 62% of hypertensive cats has increased urea or creatinine concentrations; 19.2% of cats are hypertensive at diagnosis of CKD).
  • Hyperthyroidism Hyperthyroidism, (23-87% of cases of hypertension; 22.8% of hyperthyroid cats will develop hypertension after successful antithyroid treatment).
  • Diabetes mellitus Diabetes mellitus. (NB In humans hypertension and diabetes frequently occur concurrently, but no evidence exists that this is the same in cats.)
  • Hyperadrenocorticism Hyperadrenocorticism (rare in cats, one case report describing a SBP of 300 mmHg has been published). 
  • Primary aldosteronism Feline primary hyperaldosteronism (up to 87% of cats with hyperaldosteronism are hypertensive).
  • Others, eg neurological disorders, polycythemia, syndrome of inappropriate ADH secretion.
  • Acromegaly Acromegaly.
  • Pheochromocytoma Pheochromocytomas.

Predisposing factors

General

  • Age (related to incidence of primary disease).
  • Obesity Obesity.

Specific

  • Pre-existing disease, in particular chronic kidney disease.

Pathophysiology

  • Depends on cause.
  • Often poorly understood.

Generally

  • Arterial blood pressure = cardiac output x peripheral resistance.
  • Factors affecting cardiac output and peripheral resistance:
    • Renin-angiotensin-aldosterone system.
    • Altered adrenergic activity.
    • Renal vasodepressor/vasopressor substances.
    • Sympathetic nervous system.
    • Pressure-natriuresis.
  • All are interrelated, eg in the proposed pathophysiology of hypertension in renal disease:
    • Decreased renal blood flow   →   renin/angiotensin release   →   further Na retention and vasoconstriction   →   increased renopressor substance production.
    • Anemia   →   increased cardiac output.
    • Vascular wall stiffness, eg arteriosclerosis   →   increased peripheral resistance.
  • Proposed pathophysiology of hypertension in hyperthyroidism:
    • Increased sensitivity and numbers of beta receptors in myocardium   →   increased sensitivity to catecholamines   →   increased cardiac output.
    • Thyroid hormone-specific mediators   →   increased cardiac output.
  • Sustained hypertension   →   muscular hypertrophy and necrosis of arterial walls   →   ischemia and hemorrhage   →   end organ damage especially eyes, kidneys, brain, heart.
  • Idiopathic primary hypertension has been reported - ?familial, genetic.

Timecourse

  • Usually chronic organ damage.
  • May present acutely when organ damage occurred.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Taylor S S, Sparkes A H, Briscoe K et al (2017) ISFM consensus guidelines on the diagnosis and management of hypertension in cats. J Feline Med Surg 19 (3), 288-303 PubMed.
  • Bijsmans E S, Jepson R E, Chang Y M et al (2014) Changes in systolic blood pressure over time in healthy cats and cats with chronic kidney disease. JVIM 29 (3), 855-861 PubMed.
  • Brown S, Atkins C, Bagley R et al (2007) Guidelines for the Identification, Evaluation, and Management of Systemic Hypertension in Dogs and Cats. J Vet Intern Med 21 (3), 542-558 PubMed.
  • Jepson R E, Elliott J, Brodbelt D et al (2007) Effect of control of systolic blood pressure on survival in cats with systemic hypertension. J Vet Intern Med 21 (3), 402-409 PubMed.
  • Komáromy A M, Andrew S E, Denis H M et al (2004) Hypertensive retinopathy and choroidopathy in a catVet Ophthalmol (1), 3-9 PubMed.
  • Forster-Van Hijfte M (2002) Feline hypertension: pathophysiology, clinical signs and treatment options. In Practice 24 (10), 590-594 VetMedResource.
  • Elliott J, Barber P J, Syme H M et al (2001) Feline hypertension - clinical findings and response to antihypertensive treatment in 30 cases. JSAP 42 (3), 122-129 PubMed.
  • Snyder P S, Sadel D & Jones G L (2001) Effect of amlodipine on echocardiographic variables in cats with systemic hypertension. JVIM 15 (1), 52-6 PubMed.
  • Sparkes A H, Caney S M, King M C et al (1999) Inter and intra individual variations in doppler ultrasonic indirect blood pressure measurements in healthy cats. JVIM 13 (4), 314-318 PubMed.
  • Bodey A R & Sansom J (1998) Epidemiological study of blood pressure in domestic cats. JSAP 39 (12), 567-573 PubMed.
  • Henick R A (1997) Diagnosis and Treatment of Feline Systemic Hypertension. Comp Cont Ed 19 (2), 163-179 VetMedResource.
  • Sansom J, Barnett K C, Dunn K A et al (1994) Ocular disease associated with hypertension in 16 cats. JSAP 35 (12), 604-611 VetMedResource.
  • Michell A R (1993) Hypertension in companion animals. Vet Annual 33, 11-23 VetMedResource.
  • Dukes J (1992) Hypertension - a review of the mechanisms, manifestations and management. JSAP 33 (3), 119-129 VetMedResource.

Other sources of information

  • Littman M P & Drobatz K J (1995) Hypertensive and hypotensive disorders. In: Textbook of Veterinary Internal Medicine. 4th edn. S J Ettinger & E C Feldman. Philadelphia: W B Saunders. pp 93-97.


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