Keeping the Viewer's Interest
A sense of mystery can add a significant amount of interest to a pet portrait. By not showing what the pet is looking at viewers are drawn to speculate on what is capturing this its interest. This leads them to dwell on the picture longer and enjoy the mystery.
Use Backlighting to Frame Your Pet
Backlight is created by taking pictures of your pet with the strongest light behind them. It is a powerful way to frame and highlight your pet but can easily go wrong. It is important to expose for the face at the risk of causing the backlighted areas to blow out. You can prevent the picture from becoming heavily overexposed by placing your subject against a dark background. This makes exposure easier and will add prominence to the highlighted halo of fur around your pets face and body.
A compelling photograph keeps your attention by making you ask questions. Sometimes, as in the above picture, it is about the subject but it can also be about the surroundings. What is the headlight part of and why is it in the middle of the forest?