Upload & Sell: On
Wonderful that you are here, Stephanie. From my selfish perspective, it's a fine thing to have another leonberger photographer in the group. But you'll see quite a few really well photographed dogs shown by a range of FM members.
Balto is one that many would love if they could know him, I am sure. This is a nice shot of the boy. Two thoughts come to mind as possible improvements: This is shot at f1.4 and at this close subject distance, the depth of field is unforgiving. To that end, you'll note the point of focus is at the nape of the neck, and it's only a total depth of maybe two inches. So small errors of focus are very noticeable, and I'll guess that your intent was to have Balto's eyes in focus. Stopping the lens down would, alone, have moved the focus bracket towards the eyes. There would be no harm, especially as your getting comfortable with newer gear, in shooting a given composition over a range of apertures, especially when the subject is so close as it is here. Noting that you had plenty of light so as to shoot ISO 100 1600th at 1.4, you could have still easily handheld to f8.
But it may be that your focus was in fact correctly placed at the eyes, but the camera is back-focusing with this particular lens. That brings up the issue of micro-focus adjustment, often called MA, to fine tine focus precision so that you neither front-focus nor back-focus without intending to.
Lastly the shot feels a little tight, meaning slightly looser framing of Balto would convey a little more of the environmental aspect of the portrait. But this is purely a matter of preference, naturally.
Best wishes to the boy and welcome, Stephanie.