Wolf DNA in dogs is relatively recent--from Live Science.

Denisovan cranium with jaw bone missing Prehistoric Jomon people in Japan had 'little to no' DNA from the mysterious Denisovans, study finds

https://www.livescience.com/animals/dogs/most-modern-dogs-have-wolf-dna-from-relatively-recent-interbreeding-heres-which-breeds-are-the-most-and-least-wolfish?utm_source=firefox-newtab-en-us

Wolves and dogs genetically split more than 20,000 years ago. Since then, there has been some gene flow between dogs and wolves, thanks to their genetic compatibility. To measure the extent of intermixing and its effects on both animals, researchers studied the previously published genomes of nearly 2,700 dogs and wolves from the Late Pleistocene (the last ice age) to the present. This group included 146 ancient dogs and wolves, 1,872 modern dogs and about 300 "village dogs" that lived around humans but weren't pets.

At least 264 modern dog breeds have wolf ancestry passed on from mating that occurred an average of 900 dog generations ago, which equates to about 2,600 years ago — long after dogs became domesticated at least 20,000 years ago, the team found. The most wolfish dogs had up to 40% wolf ancestry in their genomes, but most had between zero and 5% wolf ancestry.

"Prior to this study, the leading science seemed to suggest that in order for a dog to be a dog, there can't be very much wolf DNA present, if any," study co-author Audrey Lin, an evolutionary biologist at the American Museum of Natural History in New York City, said in the statement. "But we found if you look very closely in modern dog genomes, wolf is there. This suggests that dog genomes can "tolerate" wolf DNA up to an unknown level and still remain the dogs we know and love."