Age‐related differences in blood pressure, ultrasound‐derived arterial diameters and arterial wall stiffness parameters in horses

Abstract

Background: Arterial rupture mainly affects older horses. The reason why older horses are more prone to arterial rupture and which underlying vascular changes predispose older horses to aortic rupture is still unclear. Objectives: To investigate the effect of ageing on the equine arterial wall and blood pressure. Study design: Cohort study. Methods: Non-invasive blood pressure measurement using a tail cuff and vascular ultrasound from aorta, common carotid artery and external iliac artery was performed in 50 healthy young (3-7 years) and 50 healthy old Warmblood horses (>18 years). Arterial diameters and cross-sectional areas, and arterial wall thickness were measured offline. Regional arterial wall stiffness of the aorta and common carotid artery were assessed using pulse wave velocity, while lumen area/diameter change, strain, compliance and distensibility were calculated to assess local arterial wall stiffness. Results: No difference in blood pressure was found between old and young horses. All arterial dimensions and intima-media thickness of the common carotid artery were significantly larger in old horses. A significantly higher local arterial wall stiffness was found for the aorta and the caudal common carotid artery in older horses. For the external iliac artery, no significant differences in arterial wall stiffness were found. Both aortic and carotid pulse wave velocities were higher in older horses compared with younger horses. Main limitations: Blood pressure was measured non-invasively. Conclusions: In horses, arteries stiffen with age, in combination with luminal enlargement and arterial wall thickening. This might, at least partially, explain the increased incidence of arterial rupture in older horses.

Left External Iliac Artery Aneurysm in horse – Case report

“…Iliac artery aneurysm is a complex diagnosis due to limited information available in the literature regarding its classification, clinical signs, and treatments. It is of utmost importance in veterinary medicine, as it is a frequent cause of sudden death in horses (Vera et al, 2020). Through ultrasonographic images, the flow, size, and shape of vessels can be observed, allowing the diagnosis of cases of arterial dilation and rupture, hemorrhages, and flow alterations (Buhl & Ersboll, 2004).…”

Histological and biomechanical properties of systemic arteries in young and old Warmblood horses

“…In old mares, histological changes have been described in the uterine artery [ 31 ]. An increased overall arterial wall stiffness has recently been demonstrated in vivo in old horses [ 17 ]. Degradation of collagen type I has been described to be related to increased arterial wall stiffness in humans [ 32 ], but was not found in our study.…”

“…This could be ascribed to the small number of horses or to the fact that horses were considered old if aged over 15 years. Based on the chronological age, which refers to an animal’s numerical age in relation to the life expectancy, horses would have been considered old when aged >20 years, as the life expectancy of a horse is around 30 years of age [ 17 , 33 , 34 ]. Similar as in humans and rats, collagen type I and III were present in the tunica media of the equine arterial wall [ 35 , 36 ].…”

“…Nevertheless, arterial rupture is known to occur more often in older horses, especially associated with parturition in mares [ 13 ], coitus in stallions [ 14 ], intense exercise [ 15 ] or the administration of α1-agonists for treatment of left dorsal displacement of the large colon [ 16 ]. Recently, a non-invasive ultrasound study demonstrated stiffening of the conduit arteries in combination with luminal enlargement and arterial wall thickening with age in horses [ 17 ]. This might imply that structural changes of the arterial wall due to aging are likely to be one of the contributing factors leading to arterial rupture.…”

Effect of physiological and pharmacological stress on heart rate, blood pressure, and echocardiographic measurements in healthy Warmblood horses

“…Repetitive, consecutive, and noninvasive BP measurements were performed starting on and simultaneously with the acquisition of ultrasonographic images to determine diastolic arterial BP (DAP), mean arterial (MAP), and systolic arterial BP (SAP). An indirect oscillometric BP device (Cardell Veterinary Monitor, 9401, Midmark, Florida), with the cuff placed around the base of the tail (coccygeal artery), was used as previously reported by Vera et al (2020), 36 , 37 with a cuff width of 9 cm to achieve the ideal cuff width‐to‐tail circumference ratio between 0.4 and 0.6. Measurements for NIBP were taken according to the running time of the oscillometric BP device: approximately every 2 to 3 minutes at lower heart rates and approximately every minute at higher heart rates.…”