ULTRASONOGRAPHIC ASSESSMENT OF ABDOMINAL AORTIC STIFFNESS IN HYPERTENSIVE DOGS

Systemic hypertension (SH) refers to a persistent and pathological increase of arterial blood pressure (BP). In clinical practice, Doppler and oscillometric devices are commonly used to non-invasively and indirectly estimate BP[1]. Excessive movements or tremors can make difficult or even impossible to measure BP by those devices, moreover, animal’s anxiety or excitement can induce situational hypertension, leading to an erroneous diagnosis of pathologic SH[1]. Chronic SH leads to increase in aortic (Ao) stiffness[2,3], therefore, non-invasive measurements of Ao elastic properties could help clinicians to differentiate pathological from situational hypertension and to overcome measurement difficulties related to animal’s movements and tremors. The objective of our study was to compare the abdominal Ao stiffness, assessed by 2D ultrasonography (US), between hypertensive (HT) and normotensive (NT) dogs. Forty-seven dogs who presented clinical signs or conditions potentially associated with SH were prospectively included in the study. The local ethical committee (OPBSA) approved the study protocol (50675/18) and all owners signed an informed consent form before enrolment of their dogs. BP was assessed by an oscillometric device. Dogs were considered HT if systolic BP (SBP) values ≥160 mm/Hg were measured in at least 3 consecutive occasions. Ao stiffness was estimated by calculating the Ao strain (AoSt), which is the percentage change of the Ao diameter, by the following formula: AoSt=(AoDs−AoDd/AoDd)x100 [4,5] where AoDs and AoDd are the Ao diameter in systole and in diastole respectively. AoSt was calculated from 2 different abdominal Ao transverse sections, the first just caudally to the left renal artery emergence (K_AoSt) and the second just cranially to the external iliac arteries emergence (I_AoSt). Twenty-seven dogs were included in the HT group and 20 in the NT group. Both mean (SD) K_AoSt and I_AoSt of HT dogs, 7.37 (3.53) and 5.64 (2.47) respectively, were significantly lowers (P<0.05) than those calculated in NT dogs, 9.97 (3.5) and 8.16 (3.72) respectively. The K_AoSt and I_AoSt indices can provide complementary information in the diagnosis of SH in dogs especially when clinicians must differentiate true chronic hypertension from situational hypertension and when animal’s movements and tremors can make the indirect BP measurements inaccurate.