The Heart Attack singer was devastated earlier this summer (15), when her beloved pet Buddy died, and now she's started to fill the hole he left by playing mum to Batman.

The singer has posted a sweet shot of her hand placed against the sleeping black pup to show how tiny is and captioned the online shot, "Ummm... guys... meet Batman."

Paying tribute to her dead pet last month (Jul15), Lovato posted a collage of photos of herself and Buddy online, and thanked fans for their support, writing, "We can't thank you all enough. This has been the most painful week of my life but because (boyfriend) Wilmer (Valderrama) and I had so much love and support, I've been able to stay strong and will continue to get through this difficult time. The out pour of love and support has been unbelievable and it means the world to us."

It has been quite the birthday week for Lovato - she unveiled her new waxwork figure at Madame Tussauds in Hollywood, and on the eve of her birthday on Thursday (20Aug15), singer Kelly Clarkson paid tribute to her number one fan by covering her new single, Cool For The Summer, during a gig at Los Angeles' Staples Center on Wednesday night (19Aug15).