Results of radiographic assessment of cardiac size in dogs with progressing myxomatous mitral valve disease

Abstract

Chest radiography for mitral valve endocardiosis (MMVD) is both an independent and an additional method of investigation compared to echocardiography. It allows assessment of lung tissue condition, central airways, degree of vascularization, and changes in the mediastinum and pleural cavities. This study aimed to perform a radiographic examination of dogs with mitral valve endocardiosis at different stages under previously established and new indices and to determine their informativeness. The study was conducted in the private veterinary hospital “Eurovet” and at the Department of Internal Diseases of Animals and Clinical Diagnostics clinic of the Stepan Gzhytskyi National University of Veterinary Medicine and Biotechnologies of Lviv. The subjects were 25 dogs with mitral valve endocardiosis. The diagnosis was established based on the American College of Veterinary Medicine criteria. During the study, three experimental groups of animals were formed according to their clinical-functional status and the characteristics of each stage of MMVD development: groups B1, B2, and C. In group B1, 57.1 % of the animals had a slight increase in the RLAD index. With the progression of the disease, we observed a further increase in RLAD (in 80 %), a significant increase in VLAS (P < 0.01) for the first time in 40 %, as well as a decrease in RLAD-spine (P < 0.05) in 40 % and Bronchus-spine (P < 0.01) in 60 % of dogs, which generally indicates both local enlargement of the left atrium and cardiomegaly. The informativeness of the VHS index was noted at stage C (group C), as in 66.7 % of the experimental animals, its value exceeded (P < 0.001) the reference values of the norm. At the same time, we observed an increase (P < 0.05) in the mean value of RLAD by 1.3 times compared to group B1 and VLAS (P < 0.001) by 1.6 times. Between the radiographic indicators, we confirmed the presence of a strong correlation. Thus, in group B2, it was positive (r = +0.779) for VHS and RLAD and negative (r = -0.831) for VHS and RLAD-spine. In group C, a further increase in the correlation (r = +0.885) was found only between VHS and RLAD. Based on the analysis of chest radiography data, it is advisable to use radiographic indices in cases of cardiomegaly, particularly with left atrial enlargement. However, this requires their group determination and mandatory comparison with echocardiographic examination results. In veterinary practice, this has diagnostic significance for establishing the stage of the disease, as well as in the selection or correction of the therapeutic support scheme for the patient.