Sam Asghari is focusing on love that lasts ... starring in a new PETA gig with a furry companion following his bitter split from Britney Spears earlier this year.

Months after the animal rights org branded his ex 'toxic' for buying a new pup, the fitness trainer is doing his part in hammering home the message of adopting, and not buying dogs.

Sam goes shirtless in one image ... cuddling up to a pooch, with the slogan: "You Can't Buy Love, But You Can Adopt It" -- another reading: "Some Love Lasts ... Never Buy Dogs, Always Spay or Neuter."

Dog lover Sam regularly shares IG content of his Doberman, Porsha -- which was initially a gift to Britney following their 2021 engagement -- though he got to keep her in the end.

Britney got to keep the couple's 4 other dogs ... and also brought a new pooch, Snow, 2 weeks after Sam filed for divorce on Aug 16.

PETA was horrified with her purchase, venting: "She could have been a force for good and adopted, but instead she chose to be toxic, and animals will pay with their lives."