Lily Allen's Dog Rehomed, Doing Well With New Family, Says Rescue Group

Lily Allen ’s former pup has been rehomed and is living her best life with the new family ... TMZ has learned.

Animal Haven NYC tells TMZ ... Lily’s black Lab, Mary -- who she once shared with David Harbour -- has found a tail-wagging happy ending after the singer returned her to the rescue group months after her May 2021 adoption.

Tiffany Lacey , Executive Director of Animal Haven, tells us it's always their policy to take back animals if an adoption doesn't work out -- which is not uncommon with other pets too.

This could cool down the online heat Lily got for returning Mary to the shelter ... which she explained on her "Miss Me?" podcast was due to Mary misbehaving -- and chewing up their passports.

The backlash was so fierce even PETA UK jumped in ... saying they’d send her a mechanical dog toy ... noting, "It really is the only animal you should bring into your home."

Lily fired back, saying she’d been bombarded with "abhorrent messages, including death threats" ... and clarified that the passport-chewing incident was the last straw for the dog who struggled with severe separation anxiety.

Lily added the decision to return Mary wasn’t made lightly -- it came after months of agonizing over the fact she wasn’t the right fit for their family.