Alterações ecocardiográficas de cães submetidos a protocolos quimioterápicos com doxorrubicina

Abstract

Doxorubicin is a chemotherapeutic drug widely used in veterinary medicine due to its efficacy and affordability. Its cardiotoxic effects are well recognized, making it essential to seek strategies for its safe use. We conducted a systematic review and meta-analysis to evaluate the effects of this drug on the ejection fraction (EF) of dogs undergoing doxorubicin-based protocols. Thirteen studies reported echocardiographic alterations regardless of the route of administration (intravenous or intracoronary). The meta-analysis revealed an average EF reduction of 21.24%, underscoring its adverse impact on cardiac function. Additionally, a clinical study was conducted with 33 dogs treated at the Veterinary Hospital of the Federal University of Uberlândia and affiliated clinics, who were subjected to various chemotherapy protocols. The animals were evaluated at four time points (T0 to T3), with measurements of ejection fraction using the Teicholz (EFT) and Simpson (EFS) methods, fractional shortening (FS), and left ventricular dimensions in diastole and systole. Statistical analysis was performed using a linear mixed-effects model, considering time, doxorubicin use, preexisting heart disease, and their interactions. The results demonstrated statistically significant reductions in echocardiographic parameters in dogs treated with doxorubicin, either alone or in combination with other chemotherapeutic agents. Despite these changes, values remained within the physiological reference range for the species, and no clinical signs of cardiac dysfunction were observed. Chronic myxomatous mitral valve disease did not influence the occurrence of cardiotoxicity. Age, however, was a relevant factor, with adult dogs showing greater susceptibility. These findings suggest that doxorubicin cardiotoxicity exhibits a cumulative behavior and can be detected early through echocardiographic monitoring, particularly in patients exhibiting a trend toward declining cardiac function, even when values remain within normal limits. We conclude that doxorubicin is safe when used under cardiovascular monitoring, and serial surveillance of echocardiographic parameters is recommended, even in the absence of clinical signs of heart disease.