My husband is having stress echocardiogram. Will he have dobutamine injected?

Maybe. If he can walk on a treamill no. The heart has to be stressed. If for some reason he cannot walk long enough or at all on the treadmill , then Dobutamine is used to stress the heart. It will make the heart contract harder and faster just as if he were walking on a treamill.
Possibly. Either walking on a treadmill, or using a stationary bicycle or getting a Dobutamine drip iv.