Welcome to the forum. Glad to have you as part of our group.

Black and/or white animals on black or white backgrounds are difficult. You did a good first attempt. It is really important and difficult to get separation between a black dog and a black background so they do not merge; I use a overhead softbox that fuctions as sort of a hair light and background separation light but that brings up other concerns like light spillage, etc.

Of course you are seeing the problem of adding enough light to light the blacks and then blowing out the whites, that is part of the difficulty of black/white dogs.

If you have enough lights, I might try two umbrellas (plus a hair light) at 45 degree angles to the dog, from the front, pretty low to light the face and ears with very careful attention to the whites and blacks for exact exposure. Keep shooting, will look forward to future posts.