Vertebral heart score to evaluate cardiac size in thoracic radiographs of 124 healthy rats (Rattus norvegicus)

Abstract

Dilated cardiomyopathy is a relatively common disease in pet rats (Rattus norvegicus); however, there is a lack of radiographic references for the normal cardiac size in this species. The aim of this prospective, anatomical and reference interval study was to establish quantitative radiographic reference range measurements for the vertebral heart score (VHS) in rats. Right lateral (RL), ventrodorsal (VD), and dorsoventral (DV) radiographs of clinically healthy rats (n = 124) were evaluated. Measurements were performed by 2 expert readers who were unaware of signalment data. The mean values and references intervals of VHS were 7.7 and 7.0–8.5 for the RL, 7.5 and 6.6–8.6 for the VD, and 7.9 and 6.9–9.0 for the DV, with VHS values greater in males than in females. The measurements reported in this study can be used by the clinician as an objective tool to evaluate cardiac size in rats, in order to improve the diagnosis and treatment of cardiac diseases.

Radiologic indices of cardiac mensuration in the African grasscutter (Thryonomys swinderianus)

“…The reference value of VHS for the African grasscutter from this study (8.7) is higher than the values of 7.5, 7.7, 8.1 or 8.2 established for adult cats, irrespective of breed (Litster and Buchanan, 2000), pet rats (Dias et al, 2021), agoutis (De Moura et al, 2015) and African hedgehogs (Black et al, 2011) respectively. It is lower than the values of 9.3, 9.4, 9.8, 10.1, 10.3 or 10.5 established for the tufted capuchin (Rocha-Neto et al, 2015), common marmosets (Wagner and Kirberger, 2005), Nigerian indigenous dog (Ukaha et al, 2021b), west African dwarf goats (Ukaha et al, 2013), dachshund dog (Birks et al, 2017) and Australian cattle dog (Luciani et al, 2019), respectively.…”

“…Thus, reference values of VHS must be intrinsic to the breed and/or species in view, and should not be extrapolated to other breeds or species. Furthermore, Dias et al (2021) emphasized that VHS within normal limit of a named breed or species did not preclude an actual cardiac disease, mainly in cases where heart enlargement is not part of the process, as the animal can develop concentric cardiac hypertrophy without dilation. Further examination of the cardiac borders is advisable in such cases.…”

“…It is obtained by placing the vernier caliper of a defined cardiac axis over the thoracic vertebrae, parallel to the vertebral canal, and counting caudally, from the cranial extremity of the body of the 4th thoracic vertebrae, to the nearest 0.1-0.5 vertebra. Unlike the CTR that can be obtained on either the VD or DV projections only, VHS can be obtained from any of the four key thoracic radiographic projections (Luciani et al, 2019;Dias et al, 2021). A strong positive correlation has been recorded between CTR and VHS in capuchin monkeys (Rocha-Neto et al, 2015) and dogs (Baisan et al, 2016).…”

“…Therefore, reference radiographic values ought to be established and published specifically for every animal. Over the years, thoracic radiography has been used to establish normal heart size and diagnose cardiac anomalies in rodents such as African hedgehogs (Black et al, 2011), agouti (Diniz et al, 2013;De Moura et al, 2015), laboratory mice (Ulum and Noviana, 2018), pet rats (Dias et al, 2021) and guinea pigs (De Silva et al, 2022). However, to the best of the authors' knowledge, this is the first time this diagnostic image modality is applied to establish cardiac indices in the African grasscutter (Thryonomys swinderianus).…”

Vertebral heart score and cardiothoracic ratio in Wistar rats

“…This method was preferred because it is a measurement that can be calculated automatically in the x-ray machine used in our study. The closest study of our study, has been newly published by Dias et al (9). Dias et al measured the right lateral, ventrodorsal and dorsoventral VHS in Sprague-Dawley Rats (both male and female) and reported a mean of 7.70.…”