Incidence of hypoxemia is associated with echocardiographic findings in dogs with advanced myxomatous mitral valve disease.

OBJECTIVE

To evaluate arterial blood gas analysis (ABGA) findings in dogs with myxomatous mitral valve disease (MMVD), and to examine their association with echocardiographic and thoracic radiographic findings.

METHODS

In this single-center retrospective study (April 2022 to March 2024), thoracic radiography, echocardiography, ABGA, and blood pressure measurement were compared among 3 groups: the control group (without cardiac disease or with stage B1), stage B2, and stage C. In the stage B2 or C group, severity of MMVD was classified on the basis of the left atrium-to-aortic root ratio (LA:Ao; ≤ 2.0 vs > 2.0) and E-wave peak velocity (E max; ≤ 1.3 vs > 1.3 m/s). The ABGA was compared.

RESULTS

Among the enrolled dogs, 22 (90 examinations) were assigned to the stage B2 and C groups and 14 (14 examinations) to the control group. None of the dogs were diagnosed with pulmonary edema. Tracheal collapse and bronchomalacia were observed in many dogs, regardless of the group. Compared with the control group (79 mm Hg; minimum to maximum, 61 to 95 mm Hg), Pao2 was significantly decreased in the stage B2 group (68 mm Hg; 39 to 100 mm Hg) and stage C group (63 mm Hg; 41 to 100 mm Hg). Dogs with E max > 1.3 m/s and LA:Ao > 2.0 (Pao2, 57 mm Hg; 39 to 84 mm Hg) had lower Pao2 than those with E max < 1.3 m/s and LA:Ao < 2.0 (Pao2, 67 mm Hg; 51 to 100 mm Hg).

CONCLUSIONS

Our findings revealed that dogs with stage B2 or C MMVD and concurrent respiratory disease exhibited hypoxemia.

CLINICAL RELEVANCE: ABGA is suitable for detecting hypoxemia that cannot be assessed by thoracic radiography; combined with echocardiography, it may contribute to the assessment of MMVD severity.