The efficacy of administration of the angiotensin-II receptor inhibitor in dogs at different stages of myxomatous mitral valve disease (MMVD)

Progression of myxomatous mitral valve disease (MMVD) in dogs is accompanied by long-term activation of the sympathetic nervous system, renin-angiotensin-aldosterone system (RAAS) and morphological changes in the bicuspid valve. As a result, an increase in the circulating blood volume, prolonged vasoconstriction, an increase in the mitral regurgitant volume can contribute to the development of secondary arterial hypertension in this animal species. Current therapeutic protocol for the treatment of dogs with MMVD and control of systemic arterial hypertension, according to the American College of Veterinary Medicine (ACVIM) consensus statement guidelines, includes diuretics, beta-blockers, calcium channel blockers and RAAS inhibitors. The purpose of the study is to determine the effectiveness of the use of angiotensin-II receptor inhibitor (ARBs) in dogs at different stages of MMVD progression. The study was conducted in the conditions of the private veterinary hospital “Evrovet” and on the basis of the clinic of the Department of Internal Animal Diseases and Clinical Diagnostics of Stepan Gzhytskyi National University of Veterinary Medicine and Biotechnologies of Lviv. The object of investigation was 36 dogs with MMVD. Diagnosis was based on paramaters recommended by ACVIM. During the work, the animals were divided into three classes (class B1 – asymptomatic dogs, without evidence of cardiac remodeling, B2 – asymptomatic dogs, with evidence of cardiac remodeling and C – symptomatic dogs, with evidence of cardiac remodeling). According to the type of antihypertensive drugs there were created three experimental groups in each class: D1 group – enalapril was used, D2 – enalapril and spironolactone, D3 – telmisartan. The control group (K) consisted of healthy animals. According to the results of primary oscillometry, prehypertensive state was established in 73.3 % (P < 0.001) of dogs of class B1, 66.7 % (P < 0.001) of dogs of class B2 and 33.3 % (P < 0.001) of dogs of class C. The prevalence of moderate hypertension in dogs of class B2 is 33.3 % (P < 0.001), in dogs of class C – 41.7 % (P < 0.001). Severe hypertension was established in 25.0 % (P < 0.001) of dogs of class C. On the 7th day of treatment, animals of the experimental groups of all three classes showed a significant decrease in blood pressure. In particular, in class B1, groups D1, D2, D3, a decrease of 6.0 %, 6.7 %, 16.8 % was observed, respectively, in class B2 – by 9.7 %, 9.6 %, 13 %, and in class C – 7.7 %, 5.5 %, 13.5 %. However, the most pronounced decrease in the degree of arterial hypertension (by 35.8 % compared to the initial values) compared to the study groups of all classes was diagnosed on the 21st day of the study in group D3 class C, where telmisartan was used. According to the results of biochemical blood tests before the start of treatment, 8.3% (class C) of sick dogs had increased renal parameters: urea content 16.5 ± 1.43 mmol/L, creatinine 207.3 ± 30.99 μmol/L, inorganic phosphorus 3.6 ± 0.08 mmol/L, and according to the results of urine tests, proteinuria (0.6 ± 0.14 g/L). When using therapy for 21–42 days, the content of urea, creatinine and inorganic phosphorus decreased by 1.67 times, 1.44 and 1.50 times, respectively, compared to the initial values. It should be noted that during the period of use of antihypertensive drugs (1–42 days), we did not detect significant changes in the average level of sodium (B1 – 144.4 ± 0.81 mmol/L, B2 – 144.0 ± 1.59, C – 147.6 ± 1.35 mmol/L) and potassium (B1 – 4.3 ± 0.10 mmol/l, B2 – 4.4 ± 0.13, C – 4.7 ± 0.14 mmol/L) in the blood serum of experimental animals. Telmisartan is effective for treating dogs with MMVD because it lowers blood pressure, blocks angiotensin II receptors and improves hemodynamics, reducing the strain on the kidneys and myocardium.