All large and giant-breed dogs who happen to have black coats are suseptible to a toe cancer called squamous cell carcinoma (SCC). A study is ongoing at the University of
Guelph, Ontario, Canada, gathering statistics of dogs whose toes are affected.
My black Standard Poodle has just gone through his second surgery to remove a toe due to SCC. He lost his first toe, on a back foot, in 2008, after we discovered a lesion next to his toenail which refused to heal.