Phasing of a wolf - over the four year period its fur grows thicker and brighter

Progression of phasing seen on a high content black phase wolfdog from year 1 to year 4. 

WOLVES: In addition to having a unique shedding period, some wolves will also undergo a process called phasing which causes a significant change in coat color with each shed. Phasing causes animals to become lighter over time. While most wolves that phase have black coats, there are some grizzled and gray animals that phase out as well, especially if they are mixed with a lighter subspecies like Arctic or tundra. Some wolves phase out faster than others.  While it may take one wolf 12 years to phase completely to silver/white, another might phase out as fast as six years. Dogs can grey as they get older and some markings may fade, but not to the same extent as seen in wolves.

A mid content wolfdog goes from 10 months to 6 years losing its markingsPhasing as seen on an 87% F2 upper mid wolfdog cross from 10 months to 6 years of age