Acta Vet. Brno 2022, 91: 363-373

Effectiveness of therapy with low-dosage masitinib on pulmonary hypertension in dogs: a pilot study

Yu Sahashi1,2, Yoshiaki Hikasa2

1Sahashi Veterinary Hospital, Inagawa, Kawabe-gun, Hyogo, Japan
2Tottori University, Joint Graduate School of Veterinary Sciences, Department of Clinical Veterinary Science, Tottori, Japan

Received May 23, 2022
Accepted October 10, 2022

The purpose of this pilot study was to assess the efficacy of long-term masitinib therapy at low doses on echocardiographic, cardiovascular, haematological, and blood biochemical indicators, as well as clinical symptoms in dogs with pulmonary hypertension (PH) caused by advanced chronic degenerative mitral valve disease or heartworm disease. Seven client-owned dogs with severe PH were recruited prospectively and given low-dose masitinib orally, 3 mg/kg body weight (approximately one-fourth of the recommended antineoplastic dosage), q24h, for 123–928 days. Examinations were performed prior to masitinib administration, as well as 1, 2, 3, 6, and 12 months later. At 1–12 months, low-dose masitinib significantly reduced systolic pulmonary arterial pressure (P < 0.05 or 0.01) and dramatically improved clinical symptoms. Low-dose masitinib treatment improved right ventricular function indicators such as right atrium/aorta ratio, maximum tricuspid regurgitation velocity, right ventricular Tei index, and tricuspid annular plane systolic excursion, without worsening left ventricular function indicators. These findings suggest that low-dose masitinib may be effective as an adjunctive therapeutic for chronic heart failure in dogs with PH and may increase the survival of PH dogs.


The Japan Society for the Promotion of Science provided funding for this study through a Grant-in-Aid for Scientific Research (C) (no. 18K05993; to Y. Hikasa). We thank the dogs’ owners for their involvement in the study.


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