As soon as the Pomeranian had entered, Zhang Zian had noticed the brown tear marks under its eyes, as well as its brown nose. As he rubbed it in secret while holding it, he realized it was not artificial color. He had an idea about what was going on.
"This is caused by a calcium deficiency," he said with confidence. "This elderly lady barely takes it outside. Pomeranians don't need much exercise, so it would have been fine, but going outside isn't just for exercise. Dogs also get Vitamin D from the sun, and Vitamin D is related to calcium absorption. If a Pomeranian has a calcium deficiency, then these marks will appear. As long as it gets enough sunlight, the brown tear marks will disappear naturally. Its nose will also turn black again."
Everything depended on the sun to grow––it was a universal truth, especially for humans and animals undergoing growth. They all needed some sunlight to help with calcium absorption.