My Goldendoodle has dark spots on his fur. What's happening?
Hyperpigmentation of the skin/fur can be caused by a number of things, including trauma that is causing the skin or coat to need to repair itself (which can return to normal over time on its own), secondary to issues such as hypothyroidism or Cushing's disease, or in response to infections from bacteria, yeast, or fungus.
If the area does not resolve on its own, seems to be spreading, or becomes itchy or bothersome, I would have your vet take a look. They can take a sample of the area to check for infections, and may recommend bloodwork to rule out metabolic diseases, however these disease are less common in younger dogs.
In the meantime, keeping the spot clean and dry, monitoring it for any spreading, rapid changes, or new symptoms, and keeping Leo from rubbing or scratching at it may help it resolve.
Updated on September 23rd, 2025