Attenuation of the pressor response to exogenous angiotensin by angiotensin receptor blockers and benazepril hydrochloride in clinically normal cats

Use of amlodipine in the treatment of cats with systemic hypertension in Japan

An increase in systemic blood pressure causes bleeding and ischemia owing to peripheral vascular breakdown, leading to various forms of organ damage. The brain, eyes, kidneys, and cardiovascular system are known target organs for hypertension. To our knowledge, no reports in Japan describe, in detail, the types of antihypertensive drugs used to treat hypertension in cats or its underlying causes. Therefore, we aimed to investigate the use of antihypertensive drugs in domestic cats with hypertension in Japan, the causes of hypertension, and the vital prognosis of these patients. In the present survey, we found that amlodipine was used alone (60/80 cats) or concomitantly (20/80 cats) in all cat patients with hypertension in Japan. We also determined that blood pressure measurements were not yet routinely performed on cats at veterinary clinics in Japan. Furthermore, we have new information suggesting that amlodipine administration in cats with hypertension, which lowers systolic arterial pressure levels to within the normal range (<140 mmHg), may have a negative impact on their survival. Routine blood pressure measurements for cats during their regular health checkups can help identify hypertension, and proper interpretation of blood pressure readings can facilitate suitable treatment measures.

Single-dose pharmacokinetics of telmisartan oral solution and effect of feeding in dogs

Telmisartan is an angiotensin II receptor blocker that has great potential to improve the treatment of hypertension, proteinuria, and cardiovascular disease in dogs. A feline-approved telmisartan oral solution (TOS) is available, but this formulation has not been evaluated in dogs. The aims of this study were to establish the pharmacokinetics of telmisartan administered as TOS and determine the effect of feeding on drug absorption in dogs. In a cross-over design, seven healthy dogs received 1 mg/kg telmisartan orally as TOS with or without food and underwent serial measurement of plasma telmisartan concentrations over 24 h. Bioequivalence of TOS administered with vs. without food was assessed by the 90% confidence interval method for maximum concentration (C_max ), and the observed and extrapolated areas under the curve (AUC_0-t and AUC_0-∞ ). The mean ratios of these parameters were 0.97 (CI 0.74-1.27), 0.92 (0.81-1.03), and 0.90 (0.82-1.00), respectively. Feeding methods were not bioequivalent based on C_max due to interindividual variation. These results suggest that TOS can be given to dogs with or without food but should be administered in the same way consistently. Additional pharmacokinetic and pharmacodynamic studies are warranted to confirm this recommendation and establish the therapeutic targets for telmisartan in dogs.

Drug-Dosing Adjustment in Dogs and Cats with Chronic Kidney Disease

Chronic kidney disease is a common kidney disorder in adult and aged dogs and cats; the management of associated complications and comorbidities generally requires a life-long medical treatment to ensure a good quality of life of affected patients. However, indications and the literature on drug dosing in dogs and cats with chronic kidney disease are often lacking. The aim of this review is to revise the current literature on drug dosing in canine and feline patients with renal impairment, with a special focus on the most commonly used medications to manage chronic kidney disease and possible comorbidities.

Comparison of Doppler ultrasonic and oscillometric devices (with or without proprietary optimisations) for non-invasive blood pressure measurement in conscious cats

Objectives

This study compared Doppler and oscillometric (PetMAP+) devices (with or without proprietary optimisations) for the non-invasive measurement of blood pressure in conscious cats.

Methods

Twenty-three cats were enrolled; however, five were excluded as fewer than five measurements were obtained for each assessment. All measurements were obtained according to American College of Veterinary Internal Medicine consensus guidelines. Oscillometric device modes A and B were operated according to the manufacturer’s guidelines. Doppler and oscillometric devices were used alternately as the first device.

Results

Systolic arterial blood pressure (SAP) measurements were obtained by Doppler (SAPd) and oscillometry; the mean of each set of five values was used for statistical analysis. There was a significant difference between SAPd and SAP measurements in oscillometric modes A (P <0.001) and B (P <0.001). While both modes measured SAP higher than SAPd, B had a smaller bias (+15.72 mmHg) and narrower limits of agreement (LOA). There was also a significant difference between SAPd and mean arterial pressure (MAP) on oscillometric modes A (P = 0.002) and B (P <0.001). Both modes’ MAP readings were lower than SAPd and oscillometric A MAP was closer to SAPd (–14.94 mmHg), with a smaller bias and narrower LOA.

Conclusions and relevance

The findings support that Doppler and oscillometric devices cannot be used interchangeably, with or without proprietary optimisations. Methodology should always be taken into account and reference intervals (RIs) need to be defined for the different methodologies. Until methodology-specific RIs are published, definitive diagnosis of hypertension and sub-staging of patients with kidney disease according to the International Renal Interest Society guidelines remains challenging.

Safety and efficacy of orally administered telmisartan for the treatment of systemic hypertension in cats: Results of a double-blind, placebo-controlled, randomized clinical trial

BACKGROUND

Information regarding the efficacy of telmisartan for feline systemic arterial hypertension is limited.

OBJECTIVES

To evaluate the safety and efficacy of PO administered telmisartan solution in hypertensive cats.

ANIMALS

Client-owned cats with indirect systolic arterial blood pressure (SBP) of 160-200 mm Hg, based on multiple measurements.

METHODS

This multicenter trial consisted a 28-day, prospective, randomized, double-blind, placebo-controlled, parallel group, efficacy phase and a 154-day extended-use telmisartan phase. Hypertensive cats were randomly assigned to receive 1.5 mg telmisartan/kg PO q12h for 14 days, followed by 2 mg telmisartan/kg PO q24h, or equivalent volume of placebo. Systolic blood pressure was measured on days 0, 14, and 28. Change in SBP compared to baseline was calculated for days 14 and 28. Telmisartan efficacy was defined as significant decrease in SBP at day 14 compared to placebo and a clinically relevant (>20 mm Hg) decrease in SBP at day 28.

RESULTS

Two-hundred twenty-one cats were included. On day 14, least squares mean (95% confidence interval) SBP decrease was significantly larger in telmisartan-treated (-23.3 mm Hg [-28.2 to -18.3]) versus placebo-treated (-7.5 mm Hg [-13.6 to -1.5]) cats (P = .0005). On day 28, telmisartan treatment resulted in a clinically relevant SBP decrease (-23.9 mm Hg [-27.8 to -20.0]), whereas placebo did not (-11.6 mm Hg [-17.4 to -5.9 mm Hg]). The decrease in SBP persisted over the 6-month trial in telmisartan-treated cats.

CONCLUSIONS AND CLINICAL IMPORTANCE

Telmisartan significantly decreased SBP to a clinically relevant extent and was well tolerated in hypertensive cats.

The renin-angiotensin-aldosterone system and its suppression

Chronic activation of the renin-angiotensin-aldosterone system (RAAS) promotes and perpetuates the syndromes of congestive heart failure, systemic hypertension, and chronic kidney disease. Excessive circulating and tissue angiotensin II (AngII) and aldosterone levels lead to a pro-fibrotic, -inflammatory, and -hypertrophic milieu that causes remodeling and dysfunction in cardiovascular and renal tissues. Understanding of the role of the RAAS in this abnormal pathologic remodeling has grown over the past few decades and numerous medical therapies aimed at suppressing the RAAS have been developed. Despite this, morbidity from these diseases remains high. Continued investigation into the complexities of the RAAS should help clinicians modulate (suppress or enhance) components of this system and improve quality of life and survival. This review focuses on updates in our understanding of the RAAS and the pathophysiology of AngII and aldosterone excess, reviewing what is known about its suppression in cardiovascular and renal diseases, especially in the cat and dog.

Evaluation of orally administered telmisartan for the reduction of indirect systolic arterial blood pressure in awake, clinically normal cats

OBJECTIVES

The aim of this study was to compare the effects of multiple once- or twice-daily oral dosage rates of the angiotensin II, type-1 receptor blocker, telmisartan (TEL), or placebo (PLA) on indirect systolic arterial blood pressure (SBP) in awake, clinically normal cats.

METHODS

Utilizing an incomplete crossover design and following a 14 day acclimation period, 28 healthy laboratory cats were randomized to undergo treatment with three of the following 14 day treatment protocols, each separated by a 1 week washout period: oral PLA q24h, oral TEL at a dosage of 1, 1.5, 2 or 3 mg/kg q24h, or oral TEL at a dosage of 1 or 1.5 mg/kg q12h. Using the Doppler ultrasound method, indirect SBP was measured daily during each treatment period, and daily during the first 5 days of each washout period, approximately 3 h after administration of the morning treatment.

RESULTS

Each treatment protocol was administered to a total of 12 cats. A statistically significant effect of treatment period was identified for the entire study; therefore, only data from the first treatment period (four cats per treatment group) were used for further analysis. Compared with PLA, during the first treatment period, SBP values were significantly lower in cats treated with TEL at all tested dosages by the second week of treatment. SBP remained significantly lower than in PLA-treated animals for 2 days following administration of the last dose in all TEL treatment groups. No clinical signs of hypotension were noted in any group.

CONCLUSIONS AND RELEVANCE

These results suggest that treatment with TEL at a total daily dose of 1-3 mg/kg - administered as a single dose, or split into two equal doses administered 12 h apart - results in a significant, relatively long-lasting reduction of SBP in clinically normal cats. TEL appears to be well tolerated by normal cats at the dosages tested.

Hypertensive ocular disease in cats: A guide to fundic lesions to facilitate early diagnosis

PRACTICAL RELEVANCE

Systemic hypertension is common in older cats and can result in damage to organs with a rich arteriolar supply such as the eyes, kidneys, myocardium and brain. Hypertensive disease in these organs is known as target organ damage (TOD). Disease in the eye resulting from hypertension is the most easily identifiable form of TOD and can often be the reason the cat is presented to the veterinarian. Routine blood pressure measurement and fundic examination allows cats with hypertensive ocular lesions to be detected early in the course of the disease, when the lesions have the best chance of responding to treatment.

CLINICAL CHALLENGES

Detecting early evidence of TOD in the fundus requires a veterinarian to be competent in recognising lesions associated with mild hypertensive disease, as well as the more easily recognised advanced lesions that frequently result in impaired vision and blindness.

AUDIENCE

This review is written for all veterinarians who treat cats. It provides information and images to facilitate and guide veterinarians performing fundoscopy in cats, in particular in those over 7 years of age, with the aim of diagnosing hypertensive ocular lesions when they are present.

EQUIPMENT

The clinical manifestations of hypertensive ocular disease can be detected non-invasively with inexpensive equipment. A summary of the equipment available for general practitioners to perform fundoscopy is provided.

EVIDENCE BASE

This is a comprehensive review of the literature on hypertensive ocular disease in cats. The author has also included images of hypertensive ocular lesions taken in general practice to highlight the variety of lesions that can be detected.

Efficacy of long-term oral telmisartan treatment in cats with hypertension: Results of a prospective European clinical trial

Background

Efficacy of telmisartan in treating hypertension (HT) in cats has not been largely investigated.

Objective

Telmisartan oral solution effectively controls systolic arterial blood pressure (SABP) in hypertensive cats.

Animals

Two‐hundred eighty‐five client‐owned cats with systemic HT.

Methods

Prospective, multicenter, placebo‐controlled, randomized, double‐blinded study. Hypertensive cats diagnosed with SABP ≥160 mmHg and ≤200 mmHg without target‐organ‐damage were randomized (2 : 1 ratio) to receive 2 mg/kg telmisartan or placebo q24 PO. A 28‐day efficacy phase was followed by a 120‐day extended use phase. Efficacy was defined as significant difference in mean SABP reduction between telmisartan and placebo on Day 14 and group mean reduction in SABP of > 20 mmHg by telmisartan on Day 28 compared to baseline.

Results

Two‐hundred fifty‐two cats completed the efficacy and 144 cats the extended use phases. Mean SABP reduction at Day 14 differed significantly between groups (P < .001). Telmisartan reduced baseline SABP of 179 mmHg by 19.2 (95% confidence interval [CI]: 15.92‐22.52) and 24.6 (95% CI: 21.11‐28.14) mmHg at Days 14 and 28. The placebo group baseline SABP of 177 mmHg was reduced by 9.0 (95% CI: 5.30‐12.80) and 11.4 (95% CI: 7.94‐14.95) mmHg, respectively. Of note, 52% of telmisartan‐treated cats had SABP <150 mmHg at Day 28. Mean SABP reduction by telmisartan in severe (≥180 mmHg) and moderate HT (160‐179 mmHg) was comparable and persistent over time.

Conclusions and Clinical Importance

Telmisartan solution (PO) was effective in reducing SABP in hypertensive cats with SABP ≥160 mmHg and ≤200 mmHg.

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

An update to the 2007 American College of Veterinary Internal Medicine (ACVIM) consensus statement on the identification, evaluation, and management of systemic hypertension in dogs and cats was presented at the 2017 ACVIM Forum in National Harbor, MD. The updated consensus statement is presented here. The consensus statement aims to provide guidance on appropriate diagnosis and treatment of hypertension in dogs and cats.

ISFM Consensus Guidelines on the Diagnosis and Management of Hypertension in Cats

Practical relevance: Feline hypertension is a common disease in older cats that is frequently diagnosed in association with other diseases such as chronic kidney disease and hyperthyroidism (so-called secondary hypertension), although some cases of apparent primary hypertension are also reported. The clinical consequences of hypertension can be severe, related to 'target organ damage' (eye, heart and vasculature, brain and kidneys), and early diagnosis followed by appropriate therapeutic management should help reduce the morbidity associated with this condition. Clinical challenges: Despite being a common disease, routine blood pressure (BP) monitoring is generally performed infrequently, probably leading to underdiagnosis of feline hypertension in clinical practice. There is a need to: (i) ensure BP is measured as accurately as possible with a reproducible technique; (ii) identify and monitor patients at risk of developing hypertension; (iii) establish appropriate criteria for therapeutic intervention; and (iv) establish appropriate therapeutic targets. Based on current data, amlodipine besylate is the treatment of choice to manage feline hypertension and is effective in the majority of cats, but the dose needed to successfully manage hypertension varies between individuals. Some cats require long-term adjuvant therapy and, occasionally, additional therapy is necessary for emergency management of hypertensive crises. Evidence base: These Guidelines from the International Society of Feline Medicine (ISFM) are based on a comprehensive review of the currently available literature, and are aimed at providing practical recommendations to address the challenges of feline hypertension for veterinarians. There are many areas where more data is required which, in the future, will serve to confirm or modify some of the recommendations in these Guidelines.

Attenuation of the blood pressure response to exogenous angiotensin I after oral administration of benazepril to healthy adult horses

BACKGROUND

Benazepril has been shown to inhibit circulating angiotensin-converting enzyme (ACE) activity in horses but the optimal dosage is unknown.

OBJECTIVES

To determine the lowest tested dose of benazepril that results in ≥75% attenuation in the response of arterial blood pressure (BP) to exogenous angiotensin I (ANG-I) administration.

STUDY DESIGN

Prospective experimental study.

METHODS

A total of 5 healthy horses were instrumented for the direct measurement of BP. Each horse received 4 intragastric doses of benazepril (0.5, 1, 2 and 4 mg/kg bwt) with a washout period of 7 days between doses. Prior to and 2, 12 and 24 h after benazepril administration, each horse received intravenous (i.v.) boluses of ANG-I at 20, 60 and 200 ng/kg. Attenuation of the systolic arterial pressure (SBP) response to ANG-I and serum ACE activity were quantified and expressed as percentage of inhibition.

RESULTS

There was a significant effect of benazepril dose (P = 0.004) and time (P = 0.004) on the percentage of inhibition of the systolic pressor response to ANG-I. Regardless of benazepril dose, the percentage of inhibition was significantly greater 2 h after administration of benazepril compared with 12 and 24 h. At an ANG-I dose of 20 ng/kg, the percentage of inhibition after administration of benazepril at 1 mg/kg bwt (46.6 ± 18.9%) was significantly greater than that achieved after 0.5 mg/kg bwt (19 ± 14%) but not significantly different from that achieved at higher doses of benazepril. Benazepril doses ≥1 mg/kg bwt resulted in serum ACE inhibition of at least 90%.

MAIN LIMITATIONS

Small sample size and resulting low statistical power.

CONCLUSIONS

Attenuation of the rise in SBP in response to ANG-I after administration of benazepril is modest in horses despite adequate serum ACE inhibition. A dose of 1 mg/kg bwt would be recommended for future investigations of benazepril for the management of cardiovascular diseases in horses.

ISFM Consensus Guidelines on the Diagnosis and Management of Feline Chronic Kidney Disease

PRACTICAL RELEVANCE

Chronic kidney disease (CKD) is one of the most commonly diagnosed diseases in older cats. In most cats, CKD is also a progressive disease and can be accompanied by a wide range of clinical and clinicopathological changes. These ISFM Consensus Guidelines have been developed by an independent panel of clinicians and academics to provide practical advice on the diagnosis and management of this complex disease.

CLINICAL CHALLENGES

Although CKD is a common clinical problem in cats, the manifestations of disease vary between individuals. Thus there is a need for careful and repeat evaluation of cats with CKD and adjustment of therapy according to individual needs. In addition to addressing problems arising from CKD and improving quality of life (QoL) for the patient, therapy may also target slowing the underlying progression of disease and hence prolonging life. While maintaining QoL is of paramount importance in our patients, this can be challenging when multiple therapies are indicated. In some cases it is necessary to prioritise therapy, given an understanding of what is likely to most benefit the individual patient.

EVIDENCE BASE

In preparing these Guidelines, the Panel has carefully reviewed the existing published literature, and has also graded the quality of evidence for different interventions to help to provide practical recommendations on the therapeutic options for feline CKD. This is a field of veterinary medicine that has benefited from some excellent published clinical research and further research findings will undoubtedly modify the recommendations contained in these Guidelines in the future.