Yeah, I can see why you might imagine Mojo that way! I imagined him as more of a Siberian husky, myself, when I first read the books, bc a neighbor of mine had a black & white husky… the floof and the smile seemed to be a perfect fit for Mojo to me! This one here is a Siberian husky [X]:

From TOBT:

[Mojo] was covered in deep, plush fur, beautifully golden and gray in places, and overlaid
with a faint saddle of longer black hairs. His overall shape was that of a wolf, but he
was far too big to be a wolf, and there was nothing furtive and sly about him, as is the
case with wolves. On the contrary, he was wholly majestic in the way that he sat
staring motionless at the door. 

Even though it’s right there that he’s more of a German shepherd mix: 

On closer inspection, I saw that he most truly resembled a giant German shepherd,
with the characteristic black muzzle and alert face.

German shepherd w/ the black saddle pattern on the back and muzzle [X]:

I headcanon Mojo as looking sorta like this

[X]:

I can’t find it now (does anyone have it?) but I know I saw a pic of the REAL Mojo w/ Anne Rice, she confirmed that he was a long-haired German shepherd [X]: