Not always. The shelter in my town has promotional free adoption days where you get a fully vetted dog (although if it's heartworm positive, that's on you to take care of) for nothing, whereas a normal adoption fee is $86, if the dog came in with no vetting and $25, if the dog was already fixed when it came to the shelter. I got my now 9-year-old Great Dane at the shelter last year, where he was on death row, because he was a senior heartworm positive giant breed that nobody was going to be able to adopt, but I took him and the $86 I saved on his adoption fee went straight to his heartworm treatment.