ACVIM consensus statement: Guidelines for the identification, evaluation, and management of systemic hypertension in dogs and cats

Consensus Statements of the American College of Veterinary Internal Medicine (ACVIM) provide the veterinary community with up-to-date information on the pathophysiology, diagnosis, and treatment of clinically important animal diseases. The ACVIM Board of Regents oversees selection of relevant topics, identification of panel members with the expertise to draft the statements, and other aspects of assuring the integrity of the process. The statements are derived from evidence-based medicine whenever possible and the panel offers interpretive comments when such evidence is inadequate or contradictory. A draft is prepared by the panel, followed by solicitation of input by the ACVIM membership which may be incorporated into the statement. It is then submitted to the Journal of Veterinary Internal Medicine, where it is edited before publication. The authors are solely responsible for the content of the statements.
based on the latest available research, will assist practitioners in the development of a rational approach to the diagnosis and treatment of hypertension in companion animals.

## | bp measurement
Diagnosing and treating hypertension in the clinical patient necessitate accurate measurement of the patient's BP. Direct BP determination entails catheterization of a suitable artery and assessing arterial pressure using an electronic transducer. [bib_ref] Doppler ultrasonographic, oscillometric sphygmomanometric, and photoplethysmographic techniques for noninvasive blood pressure measurement..., Binns [/bib_ref] [bib_ref] New implanted chronic catheter device for determining blood pressure and cardiac output..., Garner [/bib_ref] [bib_ref] A method of measuring direct arterial blood pressure, Scully [/bib_ref] Although this is the gold standard, it is not practical for hypertension screening and treatment.
Clinically, noninvasive indirect estimations of BP such as Doppler and oscillometric devices are commonly used. [bib_ref] Hypertension in cats with chronic renal failure or hyperthyroidism, Kobayashi [/bib_ref] [bib_ref] Comparative diagnostic test characteristics of oscillometric and Doppler ultrasonographic methods in the..., Stepien [/bib_ref] [bib_ref] Blood pressures obtained by indirect measurement in conscious dogs, Coulter [/bib_ref] Ideally, BP should be measured using devices that have been validated in the species of interest and under the circumstances in which the patient is being tested. Standards for the validation of indirect BP measuring devices in people are well established, 7 but no device has met these criteria in conscious dogs or cats. For this reason, a set of standards for validating indirect BP devices in awake dogs and cats has been proposed and accepted. [bib_ref] Guidelines for the identification, evaluation, and management of systemic hypertension in dogs..., Brown [/bib_ref] Although many studies have attempted to validate indirect BP devices in anesthetized patients, only a few have been performed in conscious animals. [bib_ref] Evaluation of oscillometric and Doppler ultrasonic devices for blood pressure measurements in..., Vachon [/bib_ref] [bib_ref] Comparison of high-definition oscillometry-a non-invasive technology for arterial blood pressure measurement-with a..., Martel [/bib_ref] [bib_ref] Comparison of ultrasonic Doppler flow monitor, oscillometric, and direct arterial blood pressure..., Bosiack [/bib_ref] [bib_ref] Evaluation of oscillometric and Doppler ultrasonic methods of indirect blood pressure estimation..., Haberman [/bib_ref] In the devices studied to date in awake animals, either a different validation standard was used [bib_ref] Evaluation of oscillometric and Doppler ultrasonic devices for blood pressure measurements in..., Vachon [/bib_ref] [bib_ref] Comparison of ultrasonic Doppler flow monitor, oscillometric, and direct arterial blood pressure..., Bosiack [/bib_ref] [bib_ref] Evaluation of oscillometric and Doppler ultrasonic methods of indirect blood pressure estimation..., Haberman [/bib_ref] or the device failed to meet the previously established criteria. [bib_ref] Comparison of high-definition oscillometry-a non-invasive technology for arterial blood pressure measurement-with a..., Martel [/bib_ref] Until devices that can meet the guidelines for measuring BP in conscious animals have been validated, it is our recommendation that currently available devices be used with a degree of caution. Because estimates of BP obtained using an indirect device can only be interpreted in light of results of appropriate validation testing in conscious animals, devices that have not been subjected to appropriate testing in conscious animals should not be used. Nonetheless, studies that have relied upon indirect estimation of BP using available devices have identified adverse effects of increased BP and benefits of intervention, indicating that some of these devices can provide clinically useful information. [bib_ref] Effect of control of systolic blood pressure on survival in cats with..., Jepson [/bib_ref] [bib_ref] Association between initial systolic blood pressure and risk of developing a uremic..., Jacob [/bib_ref] Therefore, we recommend that, once commercially available, only devices that meet the established validation standards in conscious cats and dogs be used.
To obtain reliable results in the measurement of BP, it is important to follow a standard protocol . The individual taking the measurements should be skilled and experienced in the handling of animals and the equipment. Studies have shown that operator experience can have a significant impact on BP measurements. [bib_ref] Doppler ultrasonographic, oscillometric sphygmomanometric, and photoplethysmographic techniques for noninvasive blood pressure measurement..., Binns [/bib_ref] [bib_ref] Influence of the observer's level of experience on systolic and diastolic arterial..., Gouni [/bib_ref] Often the most skilled individual is a well-trained technician and not a veterinarian. Anxiety-or excitement-induced situational hypertension can be marked, [bib_ref] Evaluation of the white-coat effect in cats, Belew [/bib_ref] [bib_ref] White-coat effect on systemic blood pressure in retired racing greyhounds, Marino [/bib_ref] but can be minimized by measuring BP in a quiet area, away from other animals, before other procedures and only after the patients have been acclimated to their surroundings for 5-10 minutes.
Whenever possible, the owner should be present and restraint should be kept to a minimum. The selection of a correctly sized cuff is critical in obtaining accurate measurements. [bib_ref] Doppler ultrasonographic, oscillometric sphygmomanometric, and photoplethysmographic techniques for noninvasive blood pressure measurement..., Binns [/bib_ref] Some veterinary-specific oscillometric devices have specially designed cuffs and these should always be used. When using Doppler and many oscillometric units, the width of the cuff should be 30%-40% of the circumference of the extremity at the site of cuff placement. The first measurement should be discarded and the average of 5-7 consecutive consistent indirect measurements should be obtained. If there is substantial variation, the readings should be discarded and the process repeated. In some patients, BP trends downward as the measurement process continues.
In these animals, measurements should continue until a plateau is reached and then 5-7 consecutive consistent values should be recorded. Conversely in some patients, measurement of systolic blood pressure (SBP) may result in a progressive increase in readings. When this occurs, results must be interpreted in the clinical context of the individual patient. The animal's position and attitude, cuff size and site, cuff site circumference (cm), and name of the individual making the measurements should be carefully recorded and used for future pressure measurements. Individual patients may be noise-sensitive, but, in general, use of headphones by the measurer does not result in lower BP measurements.

## | normal values for canine and feline bp
Various studies have reported values for BP in normal dogs and cats. These values vary, reflecting differences in subject Protocol for accurate blood pressure (BP) measurement - Calibration of the BP device should be tested semiannually either by the user, when self-test modes are included in the device, or by the manufacturer. - The procedure must be standardized.
- The environment should be isolated, quiet, and away from other animals. Generally, the owner should be present. The patient should not be sedated and should be allowed to acclimate to the measurement room for 5-10 minutes before BP measurement is attempted. - The animal should be gently restrained in a comfortable position, ideally in ventral or lateral recumbency to limit the vertical distance from the heart base to the cuff (if more than 10 cm, a correction factor of +0.8 mm Hg/cm below or above the heart base can be applied). - The cuff width should be approximately 30%-40% of circumference of the cuff site.
- The cuff may be placed on a limb or the tail, taking into account animal conformation and tolerance, and user preference.
- The same individual should perform all BP measurements following a standard protocol. Training of this individual is essential.
- The measurements should be taken only when the patient is calm and motionless. - The first measurement should be discarded. A total of 5-7 consecutive consistent values should be recorded. In some patients, measured BP trends downward as the process continues. In these animals, measurements should continue until the decrease plateaus and then 5-7 consecutive consistent values should be recorded. evident in this species. [bib_ref] Epidemiological study of blood pressure in domestic cats, Bodey [/bib_ref] [bib_ref] Non-invasive blood pressure measurements in cats: clinical significance of hypertension associated with..., Mishina [/bib_ref] In a recent large study, males had higher BP than females and neutered cats had higher BP than intact animals, but the differences were very small. [bib_ref] Blood pressure measurements in 780 apparently healthy cats, Payne [/bib_ref] There are substantial interbreed differences in canine BP, most notably for hounds (eg, Greyhounds, Deerhounds) in which BP is higher than in mongrels 31 by approximately 10-20 mm Hg. [bib_ref] Epidemiological study of blood pressure in domestic dogs, Bodey [/bib_ref] [bib_ref] Arterial blood pressure, proteinuria, and renal histopathology in clinically healthy retired racing..., Surman [/bib_ref] [bib_ref] Comparative observations of the hearts of mongrel and greyhound dogs, Schneider [/bib_ref] [bib_ref] Comparison of arterial hemodynamics in the mongrel dog and the racing greyhound, Cox [/bib_ref] The BP among other breeds varies by 7-10 mm Hg 20,33 perhaps based on temperament. [bib_ref] Effect of long-term adaptation on indirect measurements of systolic blood pressure in..., Schellenberg [/bib_ref] [bib_ref] Comparison of Doppler ultrasonography and high-definition oscillometry for blood pressure measurements in..., Chetboul [/bib_ref] [bib_ref] Blood pressure, heart rate, and urinary catecholamines in healthy dogs subjected to..., Hoglund [/bib_ref] The panel recognizes the need for breedspecific BP ranges to be developed. In cats, no effect of breed has been observed on BP. [bib_ref] Epidemiological study of blood pressure in domestic cats, Bodey [/bib_ref] [bib_ref] Blood pressure measurements in 780 apparently healthy cats, Payne [/bib_ref] Obesity is associated with increases in BP in several species. [bib_ref] Obesity in dogs: effects on renal function, blood pressure, and renal disease, Joles [/bib_ref] [bib_ref] Hypertension and insulin resistance are not directly related in obese dogs, Rocchini [/bib_ref] [bib_ref] Obesity and hypertension: two epidemics or one?, Davy [/bib_ref] [bib_ref] Distribution of renal medullary hyaluronan in lean and obese rabbits, Dwyer [/bib_ref] [bib_ref] Hypertension in obese Zucker rats. Role of angiotensin II and adrenergic activity, Alonso-Galicia [/bib_ref] [bib_ref] Hypertension: a risk factor associated with weight status in dogs, Montoya [/bib_ref] This effect has been studied experimentally in dogs. [bib_ref] Obesity in dogs: effects on renal function, blood pressure, and renal disease, Joles [/bib_ref] [bib_ref] Does systemic hypertension damage the canine kidney?, Brown [/bib_ref] A small (<5 mm Hg) increase in BP was noted in obese dogs by oscillometry 20 but not by Doppler sphygmomanometry. [bib_ref] Variance of indirect blood pressure measurements and prevalence of hypertension in clinically..., Remillard [/bib_ref] The relationship between obesity and higher BP in dogs may be related to the prevalence of underlying disease. [bib_ref] Obesity-hypertension and its relation to other diseases in dogs, Perez-Sanchez [/bib_ref] In cats, no effect of obesity on BP was observed by oscillometry, [bib_ref] Epidemiological study of blood pressure in domestic cats, Bodey [/bib_ref] but cats that were underweight had slightly lower BP when measured with Doppler than those that were of ideal body weight or obese. [bib_ref] Blood pressure measurements in 780 apparently healthy cats, Payne [/bib_ref] Recent studies suggested no association among body condition score, body weight, and SBP measurements in dogs or cats, but muscle condition score and sarcopenia have been reported to affect radial but not coccygeal BP measurements in the cat. [bib_ref] Effects of various factors on Doppler ultrasonographic measurements of radial and coccygeal..., Whittemore [/bib_ref] [bib_ref] Effects of various factors on Doppler flow ultrasonic radial and coccygeal artery..., Mooney [/bib_ref] Blood pressure measurement results in normal animals are highly variable based on breed, temperament, patient position, measurement method, operator experience, and intrapatient variability, [bib_ref] Influence of the observer's level of experience on systolic and diastolic arterial..., Gouni [/bib_ref] [bib_ref] White-coat effect on systemic blood pressure in retired racing greyhounds, Marino [/bib_ref] [bib_ref] Arterial blood pressure, proteinuria, and renal histopathology in clinically healthy retired racing..., Surman [/bib_ref] [bib_ref] Effect of body position on indirect measurement of systolic arterial blood pressure..., Rondeau [/bib_ref] [bib_ref] Comparison of forelimb and hindlimb systolic blood pressures and proteinuria in healthy..., Scansen [/bib_ref] and it is difficult to determine a single value and range that might be applicable to all dogs or cats. Ranges of expected values in many studies of normal dogs and cats using various measurement techniques are presented in. In disease-free patient populations, in which the BP values typically are expected to be distributed normally,
expected normal values are presented as mean AE SD, but in hypertensive patients, the frequency distribution of BP measurements tends to be skewed with fewer patients having very high measurements. [bib_ref] Prevalence of systolic hypertension in cats with chronic renal failure at initial..., Syme [/bib_ref] For this reason, the panel recommends that data from future studies of abnormal populations be presented as median and interquartile range.

## | hypertension definitions
The term systemic hypertension is applied to sustained increases in SBP, and generally can be categorized into 1 of 3 types. It may be caused by environmental or situational stressors, it may occur in association with other disease processes that increase BP (ie, secondary hypertension), or it may occur in the absence of other potentially causative disease processes (ie, idiopathic hypertension). Accordingly, we suggest the definitions and criteria described below.

## | situational hypertension
Increases in BP that occur as a consequence of the in-clinic measurement process in an otherwise normotensive animal are termed situational hypertension. Situational hypertension is caused by autonomic nervous system alterations that arise from the effects of excitement or anxiety on higher centers of the central nervous system. This type of hypertension resolves under conditions that decrease or eliminate the physiologic stimulus (eg, altering measurement conditions to decrease the animal's anxiety and measuring BP in the animal's home environment). In people, there is question as to whether the so-called "white coat hypertension" actually represents a risk factor for subsequent hypertensive damage, with some evidence suggesting increased long-term cardiovascular risk in these, as compared to normotensive, patients. [bib_ref] White-coat hypertension, Martin [/bib_ref] [bib_ref] White coat hypertension: to treat or not to treat?, Cuspidi [/bib_ref] There presently is no justification to treat situational hypertension in dogs or cats. More importantly, anxiety-or excitement-induced increases in BP can lead to an erroneous diagnosis of true pathologic systemic hypertension. [bib_ref] Variance of indirect blood pressure measurements and prevalence of hypertension in clinically..., Remillard [/bib_ref] [bib_ref] Comparison of blood pressure measurements obtained in dogs by use of indirect..., Kallet [/bib_ref] Unfortunately, the effects of anxiety on BP are not predictable, and some animals exhibit a marked increase in BP whereas others do not. Some animals even may exhibit a decrease in BP as a result of the measurement process. [bib_ref] Evaluation of the white-coat effect in cats, Belew [/bib_ref] In human patients, awareness of the phenomena of "white coat" hypertension and of "masked hypertension"
(the latter term applied to cases in which in-clinic BP measurements are normal for a patient who is hypertensive in the nonmedical environment) has encouraged the evaluation of ambulatory or at-home BP as a complement to conventional in-clinic BP measurements. [bib_ref] ESH/ESC guidelines for the management of arterial hypertension: the task force for..., Mancia [/bib_ref] [bib_ref] Masked hypertension: understanding its complexity, Franklin [/bib_ref] Whether masked hypertension is important in veterinary species is unclear, and the use of ambulatory BP monitoring has not been systematically evaluated in veterinary medicine.

## | secondary hypertension
Secondary hypertension represents persistent, pathologically increased BP concurrent with a disease or condition known to cause hypertension, or hypertension associated with the administration of a therapeutic agent or ingestion of a toxic substance known to cause an increase in BP [fig_ref] TABLE 4: Therapeutic agents and intoxicants associated with secondary hypertension in dogs and cats... [/fig_ref]. Hypertension may persist despite effective treatment of the primary condition [bib_ref] Investigation of the role of aldosterone in hypertension associated with spontaneous pituitary-dependent..., Goy-Thollot [/bib_ref] [bib_ref] Systemic arterial blood pressure and urine protein/creatinine ratio in dogs with hyperadrenocorticism, Ortega [/bib_ref] [bib_ref] Prevalence of hypertension in hyperthyroid cats at diagnosis and following treatment, Syme [/bib_ref] and BP may increase after treatment is initiated. [bib_ref] Prevalence of hypertension in hyperthyroid cats at diagnosis and following treatment, Syme [/bib_ref] The presence of a condition known to cause secondary hypertension, even if effectively resolved by therapeutic intervention, should prompt serial follow-up evaluations.

## | idiopathic hypertension
The term "primary" or "essential" hypertension often is used in people to describe persistent pathological hypertension in the absence of any identifiable underlying cause and represents a complex multifactorial disorder involving genetic, lifestyle, and environmental factors. Essential hypertension has been reported in dogs. [bib_ref] Essential hereditary hypertension in dogs: a new animal model, Bovee [/bib_ref] Although secondary hypertension is most common in dogs and cats, idiopathic hypertension is more common than previously recognized, accounting for approximately 13%-20% of cases in cats. [bib_ref] Effect of control of systolic blood pressure on survival in cats with..., Jepson [/bib_ref] [bib_ref] Ocular lesions associated with systemic hypertension in cats: 69 cases (1985-1998), Maggio [/bib_ref] [bib_ref] Feline hypertension: clinical findings and response to antihypertensive treatment in 30 cases, Elliott [/bib_ref] Approximately 12% of nonazotemic nonhyperthyroid cats were hypertensive at baseline in one report, [bib_ref] Evaluation of predictors of the development of azotemia in cats, Jepson [/bib_ref] and in a more recent study of 133 apparently healthy initially normotensive cats aged 9 years, 7% developed idiopathic hypertension over the study's follow-up period. [bib_ref] Changes in systolic blood pressure over time in healthy cats and cats..., Bijsmans [/bib_ref] 

## | target organ damage (tod)
Systemic hypertension is problematic only because chronically sustained increases in BP cause injury to tissues; the rationale for treatment of hypertension is prevention of this injury. Damage that results from the presence of sustained high BP is commonly referred to as end organ or TOD [fig_ref] TABLE 5: Evidence of target organ damage [/fig_ref] and the presence of TOD generally is a strong indication for antihypertensive treatment.
Hypertension has been associated with proteinuria and histological renal injury in both experimental studies and in naturally occurring disease, an effect that has been identified in several species including humans, [bib_ref] Microalbuminuria: what is it? Why is it important? What should be done..., Bakris [/bib_ref] What remains unproven, at least in dogs and cats, is whether or not this decrease in proteinuria with antihypertensive drug treatment mitigates renal injury, or is simply a surrogate for improved renal outcomes, such as rate of decrease in GFR (usually assessed by measurement of serum creatinine concentration) or renal-related mortality. [bib_ref] Effect of control of systolic blood pressure on survival in cats with..., Jepson [/bib_ref] [bib_ref] Benazepril in Renal Insufficiency in Cats Study Group. Tolerability and efficacy of..., King [/bib_ref] Although the benefit is unproven, hypertension-induced or hypertension-exacerbated proteinuria currently remains an attractive target for treatment in veterinary patients.
Several epidemiological studies have associated hypertension with proteinuria (and in some studies specifically albuminuria) in cats with naturally occurring diseases. [bib_ref] Survival of cats with naturally occurring chronic renal failure is related to..., Syme [/bib_ref] [bib_ref] Benazepril in Renal Insufficiency in Cats Study Group. Tolerability and efficacy of..., King [/bib_ref] [bib_ref] Clinicopathological variables predicting progression of azotemia in cats with chronic kidney disease, Chakrabarti [/bib_ref] In addition, albuminuria has been related to an increase in BP in experimental studies of induced renal disease in cats. [bib_ref] Effects of the calcium channel antagonist amlodipine in cats with surgically induced..., Mathur [/bib_ref] A recent study of cats found that even with anti-hypertensive treatment, higher time-averaged SBP was associated with glomerulosclerosis and hyperplastic arteriolosclerosis Chronic, high-dose sodium chloride
- BP in normal cats and dogs appears to be relatively salt-insensitive. [bib_ref] Effects of dietary salt intake on renal function: a 2-year study in..., Reynolds [/bib_ref] [bib_ref] Dietary NaCl does not affect blood pressure in healthy cats, Luckschander [/bib_ref] [bib_ref] Effects of sodium chloride on selected parameters in cats, Kirk [/bib_ref] [bib_ref] Immune response after neonatal transfer of a human factor IX-expressing retroviral vector..., Xu [/bib_ref] - High-sodium diets do not appear to promote HT in cats with reduced renal function, [bib_ref] Effects of dietary sodium chloride intake on renal function and blood pressure..., Buranakarl [/bib_ref] [bib_ref] Effects of sodium chloride on selected parameters in cats, Kirk [/bib_ref] and salt-induced HT in the dog seems to be limited to experimental models that also involve nephrectomy [bib_ref] Effect of changes in salt intake on Aterial pressure and renal function..., Langston [/bib_ref] [bib_ref] Hypertension caused by salt loading in dog. 3. Onset transients of cardiac..., Coleman [/bib_ref] or mineralocorticoid administration. [bib_ref] Renal hemodynamics and vascular reactivity in canine DOCA-salt hypertension, Goering [/bib_ref] - BP effects of high-sodium intake in cats and dogs with pre-existing naturally occurring systemic HT, have not been systematically evaluated.
Intoxicants with which systemic hypertension has been reported/associated:
[formula] Cocaine 270,271 Dog [/formula]
Methamphetamine/amphetamine 272-274 Dog

## 5-hydroxytryptophan 275 dog
Agents associated with systemic hypertension in people, but whose BP effects have not been well characterized in dogs and cats: guarana (caffeine), ma huang (ephedrine), tacrolimus, licorice, and bitter orange. [bib_ref] The seventh report of the joint National Committee on prevention, detection, evaluation,..., Chobanian [/bib_ref] [bib_ref] Dietary supplements and hypertension: potential benefits and precautions, Rasmussen [/bib_ref] lesions after the patient's death. [bib_ref] Histomorphometry of feline chronic kidney disease and correlation with markers of renal..., Chakrabarti [/bib_ref] However, this effect was not replicated in a second, smaller, study. [bib_ref] A comparison of biochemical and histopathologic staging in cats with chronic kidney..., Mcleland [/bib_ref] In dogs with azotemic CKD, magnitude of BP has been associated with proteinuria, and this has been associated with shortened survival times. [bib_ref] Association between initial systolic blood pressure and risk of developing a uremic..., Jacob [/bib_ref] [bib_ref] Associations between proteinuria, systemic hypertension and glomerular filtration rate in dogs with..., Wehner [/bib_ref] Hypertension also was associated with shorter renal survival, but only if proteinuria was excluded from the analysis. 14 Proteinuria was directly related to the extent of increase in BP and to the rate of decrease in GFR in an experimental study in dogs. [bib_ref] Association of systemic hypertension with renal injury in dogs with induced renal..., Finco [/bib_ref] Dogs with leishmaniasis frequently have proteinuria and systemic hypertension, even when nonazotemic, although in this setting the proteinuria is thought to relate mainly to immune-mediated glomerular lesions, rather than occurring as a consequence of the hypertension. [bib_ref] Systemic hypertension in dogs with leishmaniasis: prevalence and clinical consequences, Cortadellas [/bib_ref] [bib_ref] Hypertension and its correlation with renal lesions in dogs with leishmaniosis, Braga [/bib_ref] Hypertensive greyhounds have an increased prevalence of microalbuminuria, although most dogs do not have histological evidence of renal injury. [bib_ref] Arterial blood pressure, proteinuria, and renal histopathology in clinically healthy retired racing..., Surman [/bib_ref] Hypertension may be present in any stage of CKD, and serum creatinine concentration is not directly related to BP. [bib_ref] Hypertension in cats with chronic renal failure or hyperthyroidism, Kobayashi [/bib_ref] [bib_ref] Absence of hypertension in dogs with renal insufficiency, Michell [/bib_ref] Hypertensive cats and dogs often have minimal or no azotemia. [bib_ref] Systemic hypertension in dogs with leishmaniasis: prevalence and clinical consequences, Cortadellas [/bib_ref] Ocular lesions are observed in many cats with hypertension and although prevalence rates for ocular injury vary, the frequency of ocular lesions has been reported to be as high as 100%. [bib_ref] Spontaneous systemic hypertension in dogs: five cases (1981-1983), Littman [/bib_ref] which occur with chronic hypertension in people, [bib_ref] Hypertension and cognitive function: pathophysiologic effects of hypertension on the brain, Manolio [/bib_ref] also are observed in dogs and cats. [bib_ref] Concurrent medical conditions and long-term outcome in dogs with nontraumatic intracranial hemorrhage, Lowrie [/bib_ref] A recent study described lesions on magnetic resonance imaging consistent with vasogenic edema in the occipital and parietal lobes of the brain in affected cats and dogs with neurologic signs. [bib_ref] Clinicopathologic and MRI characteristics of presumptive hypertensive encephalopathy in two cats and..., O&apos;neill [/bib_ref] Hypertension appears to be a risk factor for ischemic myelopathy of the cranial cervical spinal cord, resulting in ambulatory tetraparesis or tetraplegia with intact nociception in old cats. [bib_ref] Feline ischaemic myelopathy with a predilection for the cranial cervical spinal cord..., Simpson [/bib_ref] Cardiac abnormalities are common in hypertensive cats 63,64,82 and dogs. [bib_ref] Echocardiographic and tissue Doppler imaging alterations associated with spontaneous canine systemic hypertension, Misbach [/bib_ref] When affected, the heart is a target organ and increased cardiac output is rarely the cause of hypertension in animals. [bib_ref] Ocular lesions associated with systemic hypertension in cats: 69 cases (1985-1998), Maggio [/bib_ref] [bib_ref] White-coat effect on systemic blood pressure in retired racing greyhounds, Marino [/bib_ref] Nevertheless, a risk of TOD has been proposed for these dogs when in-hospital SBP is >180 mm Hg.These guidelines likely will be refined as additional breed-specific information becomes available.
In people, decreasing BP in hypertensive people lowers the risk of should be adjusted on re-evaluation if SBP is 160 mm Hg, with a minimal goal of treatment being to achieve a decrease in SBP to 160 mm Hg. Blood pressure <120 mm Hg, combined with clinical findings of weakness, syncope, or tachycardia, indicates systemic hypotension and treatment should be adjusted accordingly .
Although frequently recommended as an initial step in the pharmacological management of high BP , dietary salt restriction is controversial, [bib_ref] Idiopathic hypertension in a cat with secondary hypertensive retinopathy associated with a..., Turner [/bib_ref] [bib_ref] Effects of dietary sodium intake on blood pressure measurements in partially nephrectomized..., Greco [/bib_ref] [bib_ref] Effects of dietary sodium chloride intake on renal function and blood pressure..., Buranakarl [/bib_ref] and available evidence suggests that substantial sodium restriction alone generally does not decrease BP. [bib_ref] Effects of dietary sodium intake on blood pressure measurements in partially nephrectomized..., Greco [/bib_ref] [bib_ref] Effects of dietary sodium chloride intake on renal function and blood pressure..., Buranakarl [/bib_ref] [bib_ref] Clinical and metabolic findings in dogs with chronic renal failure fed two..., Hansen [/bib_ref] Although sodium restriction activates the renin-angiotensin-aldosterone system (RAAS) axis [bib_ref] Essential hypertension in a dog, Bovee [/bib_ref] [bib_ref] Long-term regulation of arterial pressure, glomerular filtration and renal sodium reabsorption by..., Hall [/bib_ref] generally are not salt-sensitive, high salt intake may produce adverse consequences in some settings, [bib_ref] Salt restriction reduces hyperfiltration, renal enlargement, and albminuria in experimental diabetes, Allen [/bib_ref] [bib_ref] Hypertension caused by salt loading in the dog. 3. Onset transients of..., Coleman [/bib_ref] including animals with CKD. [bib_ref] Idiopathic hypertension in a cat with secondary hypertensive retinopathy associated with a..., Turner [/bib_ref] The panel therefore recommends avoiding high dietary sodium chloride intake. However, the selection of appropriate diet should include other patient-specific factors, such as underlying or concurrent diseases and palatability. If an antihypertensive regimen is ineffective, the usual decision is to increase the dosage of currently used agents or to add an alternative agent. A variety of other agents have BP-lowering efficacy [fig_ref] TABLE 7: Oral antihypertensive agents [/fig_ref] and these may be used as appropriate in patients for which risk reduction is not adequate with ACEi or CCB or a combination of Severely hypertensive (high TOD risk) SBP 180 mm Hg these drugs . Although diuretics are frequently administered to hypertensive people, these agents are not first-choice drugs for veterinary patients, particularly given the prevalence of CKD in hypertensive dogs and the adverse consequences of diuretic-induced dehydration and volume depletion in this setting. However, diuretics can be considered in the small subset of hypertensive animals in which volume expansion is clinically apparent (eg, those with edema).

## | management of hypertension in dogs
Antihypertensive agents in general, and RAAS inhibitors in particular, should be used with caution in dehydrated dogs in which GFR may decrease precipitously with their use. Unless severe hypertension with rapidly progressive TOD is present, these patients should be carefully rehydrated and then re-evaluated before instituting antihypertensive treatment.

## | management of hypertension in cats
Despite the potential role of either the systemic or intrarenal RAAS axis in the pathogenesis or maintenance of hypertension, [bib_ref] Non-invasive blood pressure measurements in cats: clinical significance of hypertension associated with..., Mishina [/bib_ref] [bib_ref] Factors influencing the relationship between the dose of amlodipine required for blood..., Bijsmans [/bib_ref] Although transdermal application has been explored, efficacy of this route of administration has not been established and PO administration is therefore the preferred route of administration. [bib_ref] Treatment of feline hypertension with transdermal amlodipine: a pilot study, Helms [/bib_ref] [bib_ref] Transdermal amlodipine besylate in lipoderm for the treatment of feline hypertension: a..., Mixon [/bib_ref] Adverse effects of amlodipine, including peripheral edema and gingival hyperplasia, are rarely reported in the dog and are also uncommon in cats. Although gingival hyperplasia has been reported in licensing studies during administration to young healthy cats, this seems to be relatively rare in clinical practice. [bib_ref] Generalised peripheral oedema associated with amlodipine therapy in two dogs, Creevy [/bib_ref] [bib_ref] Amlodipine induced gingival hyperplasia in a Great Dane, Pariser [/bib_ref] Despite dramatic antihypertensive efficacy, longitudinal control of SBP with amlodipine besylate has not been shown to increase survival time in hypertensive cats, [bib_ref] Feline hypertension: clinical findings and response to antihypertensive treatment in 30 cases, Elliott [/bib_ref] [bib_ref] Effect of control of systolic blood pressure on survival in cats with..., Jepson [/bib_ref] and its use may activate the systemic or intrarenal RAAS. [bib_ref] Plasma renin activity and aldosterone concentrations in hypertensive cats with and without..., Jepson [/bib_ref] A key predictive factor in the survival of hypertensive cats is proteinuria. A significant decrease in proteinuria has been identified in cats that are initially either borderline proteinuric or proteinuric when treated with CCB. [bib_ref] Effect of control of systolic blood pressure on survival in cats with..., Jepson [/bib_ref] However, although the combined use of amlodipine and an ACEi or amlodipine and an ARB is reportedly well tolerated, [bib_ref] Comparison of efficacy of long-term oral treatment with telmisartan and benazepril in..., Sent [/bib_ref] [bib_ref] Effect of concomitant amlodipine and benazepril therapy in the management of feline..., Elliott [/bib_ref] studies exploring any additional survival benefit of add-on antiproteinuric agents in hypertensive cats that remain proteinuric after BP control with amlodipine besylate are lacking. Nevertheless, based on the potential for proteinuria to contribute to the development and progression of renal disease in cats and its association with survival of cats with CKD, [bib_ref] Evaluation of predictors of the development of azotemia in cats, Jepson [/bib_ref] [bib_ref] Survival of cats with naturally occurring chronic renal failure is related to..., Syme [/bib_ref] [bib_ref] Clinicopathological variables predicting progression of azotemia in cats with chronic kidney disease, Chakrabarti [/bib_ref] antiproteinuric treatment should be considered in this situation. [bib_ref] Proteinuria in cats, Syme [/bib_ref] [bib_ref] Management of proteinuria in dogs and cats with chronic kidney disease, Vaden [/bib_ref] Telmisartan is an ARB currently licensed in Europe for the treatment of feline proteinuria due to CKD. [bib_ref] Comparison of efficacy of long-term oral treatment with telmisartan and benazepril in..., Sent [/bib_ref] Initial studies in healthy anesthetized cats undergoing radiotelemetric BP monitoring, telmisartan, but not losartan, significantly attenuated the pressor response to angiotensin I. [bib_ref] Attenuation of the pressor response to exogenous angiotensin by angiotensin receptor blockers..., Jenkins [/bib_ref] Attenuation of the SBP rise was significantly higher than for benazepril when telmisartan was administered at a higher than currently licensed dosage (3 mg/kg PO q24h). [bib_ref] Attenuation of the pressor response to exogenous angiotensin by angiotensin receptor blockers..., Jenkins [/bib_ref] [bib_ref] Safety of benazepril in 400 azotemic and 110 non-azotemic client-owned cats, Lavallee [/bib_ref] Deterioration in renal function tests and uremic crisis also was reported as an adverse event in 2/112 cats and 1/112 cats receiving telmisartan, respectively, although the initial stage of CKD in these cats is uncertain from data provided. [bib_ref] Comparison of efficacy of long-term oral treatment with telmisartan and benazepril in..., Sent [/bib_ref] In contrast, no alteration in serum creatinine concentration would be anticipated with introduction of a CCB such as amlodipine besylate. [bib_ref] Feline hypertension: clinical findings and response to antihypertensive treatment in 30 cases, Elliott [/bib_ref] Clinicians should be aware of the potential for acute exacerbation of azotemia with concurrent ACEi and ARB, and careful monitoring is recommended. [bib_ref] Benazepril in Renal Insufficiency in Cats Study Group. Tolerability and efficacy of..., King [/bib_ref] [bib_ref] Effects of the angiotensin converting enzyme inhibitor benazepril in cats with induced..., Brown [/bib_ref] [bib_ref] Controlled clinical evaluation of enalapril in dogs with heart failure: results of..., Group [/bib_ref] [bib_ref] Effects of enalapril maleate on survival of dogs with naturally acquired heart..., Ettinger [/bib_ref] Angiotensin converting enzyme inhibitors and ARB should not be started in dehydrated cats in which GFR may decrease precipitously. These patients should be carefully rehydrated and then re-evaluated before instituting ACEi or ARB treatment.
Although several other antihypertensive agents ( Pheochromocytoma has been reported rarely in the cat. [bib_ref] Adrenal pheochromocytoma with contralateral adrenocortical adenoma in a cat, Calsyn [/bib_ref] [bib_ref] Adrenal pheochromocytoma in a cat, Henry [/bib_ref] [bib_ref] Plasma free metanephrines in healthy cats, cats with non-adrenal disease and a..., Wimpole [/bib_ref] [bib_ref] Apocrine gland adenocarcinoma and pheochromocytoma in a cat, Chun [/bib_ref] Combination treatment with phenoxybenzamine, an  1 -and  2adrenergic blocker, and amlodipine besylate, may be required to adequately control BP in affected cats. [bib_ref] Plasma free metanephrines in healthy cats, cats with non-adrenal disease and a..., Wimpole [/bib_ref] For cats in which tachyarrhythmias are of concern, beta-adrenergic blocker (eg, atenolol) treatment may be considered, but it should only be added after -adrenergic blockade. For cats undergoing adrenalectomy, careful BP monitoring is required in the postoperative period, as persistent hypertension or hypotension may occur. repeated to a total dosage of 3.75 mg/kg, followed by a CRI of 25 g/ kg/min), hydralazine (loading dosage of 0.1 mg/kg IV over 2 minutes, followed by a CRI of 1.5-5.0 g/kg/min) or nitroprusside (0.5-3.5 g/ kg/min IV CRI), although none of these medications has the advantage of renal vasodilatation. Phentolamine, a short-acting competitive -adrenergic blocking drug anecdotally has been used successfully to manage intraoperative hypertension that may occur during removal of pheochromocytomas (loading dose, 0.1 mg/kg IV; CRI, 1 to 2 g/kg/ min). [bib_ref] Surgical management of adrenal gland tumors with and without associated tumor thrombi..., Kyles [/bib_ref] In cats, even anecdotal information regarding the use of parenterally administered vasodilators is sparse. Subcutaneous administration of hydralazine (1.0-2.5 mg per cat SC) has been used to treat acute hypertension in postoperative feline renal transplant patients. [bib_ref] Management of hypertension controls postoperative neurologic disorders after renal transplantation in cats, Kyles [/bib_ref] In all cases of parenteral vasodilator administration, continuous or fre- To bridge these gaps, we recommend large multicenter clinical studies aimed at refining our understanding of normal BP and how it is best assessed. In addition, long-term studies are necessary to determine the best approach to hypertension treatment, and how these treatments will affect patient quality of life and life expectancy of our patients. We hope this document will be updated periodically to reflect advances in the field of veterinary medicine.

## | hypertensive emergencies

# Acknowledgments
[fig] 7 |: DIAGNOSIS OF HYPERTENSION The diagnosis of hypertension always should be based on reliable BP measurements, and therapeutic decisions in cats and dogs typically are based on SBP results (Figure 1). The presence of TOD (eg, retinopathy and CKD) justifies initiating treatment after a single measurement session, but in most cases, results should be confirmed by measurements repeated on multiple (>2) occasions. In cases of prehypertension (140-159 mm Hg) or hypertension at moderate risk of TOD (160-179 mm Hg), these measurement sessions can occur over 4-8 weeks. With more severe hypertension (180 mm Hg), however, the risk of TOD dictates that the measurement sessions be completed in 1-2 weeks. Once increases in BP are determined to be persistent, and not associated with measurement error or situational hypertension, the search for conditions associated with secondary hypertension ( [/fig]
[fig] FIGURE 1: The recommended approach to the evaluation of a possibly hypertensive patient involves reliable measurements of blood pressure as well as the identification of possible target organ damage. Once a diagnosis of hypertension is established, a search for a compatible underlying condition and appropriate treatment should commence8.1 | General treatment guidelinesBecause hypertension in dogs and cats often is secondary (80% of cases), antihypertensive drug treatment should be initiated along with treatment for any underlying or associated condition. Initial considerations (Figure 2) always should include identification and management of conditions likely to be causing secondary hypertension and identification and treatment of TOD. If possible, these considerations should be addressed with specific targeted diagnostic and therapeutic regimens. Effective management of a condition causing secondary hypertension may lead to complete or partial resolution of the high BP in some, but not all, cases.4,14,55 Decisions to use antihypertensive drugs should be based on the integration of all clinically available information, and a decision to treat (which may effectively mandate lifelong drug treatment) warrants periodic re-evaluation.Treatment for hypertension must be individualized to the patient and take into account concurrent conditions. Once daily treatment is ideal; fewer treatments always are preferred. A gradual persistent decrease in BP is the therapeutic goal. Acute marked decrease in BP should be avoided. If the chosen antihypertensive agent is only partially effective, the usual approach is to consider increasing the dosage or adding an additional drug. Management of highly resistant hypertension in people often requires multiagent (2) protocols; a similar situation often occurs in dogs, although this appears to be relatively rare in cats. It is often helpful to discuss with the owner the interindividual variability of response to antihypertensive medications when the first medication is prescribed, and the need for frequent monitoring until a therapeutic goal is reached.The goal of antihypertensive treatment is to decrease the likelihood and severity of TOD. Hypertension generally is not an emergency, and rapid decreases in BP usually should not be sought aggressively. Studies in people indicate that reduction of risk for TOD by antihypertensive treatment is a continuum and that the lower the BP, the lower the risk for TOD. Results of a recent laboratory study in dogs78 suggest that BP is a continuous risk marker for progression of kidney disease and may justify a similar treatment approach in veterinary patients. The panel feels that regardless of the initial magnitude of BP, the goal of treatment should be to maximally decrease the risk of TOD (SBP < 140 mm Hg) and that antihypertensive treatment [/fig]
[table] TABLE 4: Therapeutic agents and intoxicants associated with secondary hypertension in dogs and cats DOC) is associated with statistically significant increases in BP,245,246 most especially when combined with unilateral nephrectomy or high dietary sodium intake.247,248  Desoxycorticosterone pivalate (DOCP), administered at clinically relevant dosage rate (2.2 mg/kg IM q 30 days) to dogs with naturally occurring hypoadrenocorticism was not associated with significant increase in BP.249 Worsening or onset of systemic HT is common in animals with CKD related anemia when treated with recombinant human erythropoietin,250 recombinant canine or feline erythropoietin, 251,252 or darbepoetin alfa. 253,254  96% of dogs administered darbepoetin alfa experienced an increase in BP 253  37% of previously normotensive cats developed HT during darbepoetin alfa treatment 254  HT noted in 40% and 50% of dogs and cats, respectively, treated with rhEPO 250  It is difficult to know to what degree disease progression alone contributes to observed BP increases. Persistent HT is uncommon when administered long-term at recommended dosage (1.5 mg/kg PO q8h) in incontinent dogs. 256,257  At high doses, acute intoxication may cause severe systemic HT. 258,259 Phenylephrine hydrochloride Dog Systemic HT reported in normal dogs, 260 and those scheduled for cataract surgery, 261 administered topical ocular phenylephrine hydrochloride. Ephedrine Dog Significant increases in direct BP were noted in normal dogs administered ephedrine (1.5 mg/kg PO q12h). 262 Pseudoephedrine Dog  At high doses, acute intoxication may cause systemic HT. 263  When administered for long term to dogs with urinary incontinence, significant increases in indirect BP were not noted. 257 Toceranib phosphate Dog Systemic HT documented in 28% of previously normotensive dogs treated for various neoplastic diseases for 14 days. 264 [/table]
[table] TABLE 5: Evidence of target organ damage (TOD) There are 2 clear indications for evaluating BP in a patient for which systemic hypertension may be a concern. First, BP should be measured in patients with clinical abnormalities consistent with hyperten-fore, it may be prudent to screen older animals for these conditions.The prevalence of hypertension in dogs and cats is not known. Surfalse diagnosis is likely to be high with widespread screening. Therefore, the panel does not recommend routine screening of all dogs and cats for the presence of systemic hypertension. Some conditions (eg, hyperthyroidism, hyperadrenocorticism, and CKD) that result in secondary hypertension are more prevalent in older animals, yet may be occult. Thus, it is reasonable to institute annual screening of cats and dogs 9 years of age. Still, high BP in otherwise healthy, particularly young, animals should be assumed to represent situational hypertension until proven otherwise with confirmatory measurements on multiple occasions. [/table]
[table] Table 3: should begin. [/table]
[table] TABLE 7: Oral antihypertensive agents [/table]