First off, I've gotta credit Starfinder for making the tutorials I used to make my photo-realistic work. Her website has tutorials with a similar style. I often point to her when people ask "how do you do that?", but her website's tutorial links aren't working sometimes (her tutorials are also much better and simpler to follow, plus she's got more experience doing this kinda stuff).
Second, don't use a reference photo and try to draw exactly from the picture. I look at several photos to get a good sense of the overall pattern of fur and shape of the animals or humans I'm drawing, don't look at just one picture. If you do make a picture that looks exactly like your reference, please post link of the picture you ref'ed from. It's artistic courtesy because photographers work hard to get the right focus and composition for their pictures.
Also, I rushed when I made this so there are several mistakes. I note them when they pop up and I try to avoid spelling errors.
Enjoy!