Andy Cook, behavioural welfare adviser at the Brent Knoll Animal Centre, said it appeared that Daisy had been used for backyard breeding, and had "a number of mammary masses" - lumps that develop in breast tissue, which can be cancerous.
The couple struggled to hold back tears as they saw Daisy again, as Mrs Potter, 80, said she and her husband are "so, so grateful" for the RSCPA.
It comes just months after another stolen dog called Daisy was reunited with her owners - eight years after being taken from her home in Mole Valley, Surrey, in 2016.
Rita and Philip Potter said it was a "dream come true" to see Daisy, a Labrador, again after the RSPCA tracked her down.
He said Daisy also "has slight hip dysplasia and her coat was quite dirty when she came to us as though she had not been groomed for many years".
