Demi Lovato and Wilmer Valderrama are in mourning after losing their beloved dog Spawn. The 23-year-old entertainer took to Instagram to pay tribute to her four-legged friend, who passed on Sunday.

"I miss you so much already beautiful boy. When I first met you 6 years ago, I was intimidated by your size and your strong presence.. But as I got to know you, I learned you were just one big teddy bear. One handsome teddy bear that's for sure," she wrote alongside a photo her in a bikini being licked by her dog.

The "Cool for the Summer" singer recalled the way her dog would run to the car every time she came home or how Spawn was protective of her other dogs, Buddy and Batman, and never got "annoyed with them when they were excited hyper puppies."

"I'm going to miss the way you would nudge at my hand if I wasn't petting you," she added. "I'll even miss the way I'd need a Benadryl every time you'd give me kisses just like the way you're giving me kisses in this very picture. All the sneezes, the runny noses, even the occasional hives.. They were all worth it with you. Saying goodbye absolutely broke my heart and I felt as if I was saying farewell to a family member."

"The only thing that brings me comfort in this situation is knowing that Buddy is probably really happy he now gets to play with his big brother in Heaven.. We love you so much Spawn.. We miss you so much and we will never ever EVER forget you. RIP baby boy."

Valderrama also wrote a touching Instagram post to his dog, calling him the "best and prefect dog." He later added a sweet photo collage of him kissing Spawn. He captioned the post, "Thinking of how loving you were my handsome boy.. I miss you Spawn.. #RIPSpawn."

In July, the "Confident" singer opened up about losing her dog, Maltipoo, who died at the hands of coyotes in her backyard.

 Yesterday, I said goodbye to my handsome boy Spawn, this year has been quite a roller coaster.. Lots of emotions and lots thresholds crossed. This boy was there for it all.. 8 years worth of memories and ups and downs. since he was a puppy he had this human like presence, everyone that knew this boy know exactly what I'm talking about.. No matter what I'd be going through he just knew and would rest his little head on my lap as if saying "dad it's never that bad".. I would immediately smile and say "ok ok you're right". He had this presence, I mean he was just so freaking handsome.. Bitches loved him and lads wanted to be him HAHA.. He loved people and people LOVED him.. He was the BEST and perfect dog.. So polite, so welcoming and just good GOOD boy.. I have never had such a loving dog.. He just loved being around us all.. He never lost his innocence.. He would keep my mom company all day.. Wherever she move he'd follow as if taking care of her. Spawn my boy you completed our family.. You were the alpha and my son.. I saw you go from a little pup with your ears taped to the most beautiful Doberman I have ever seen.. I love you so much and I am going to miss you so freaking much.. Touching you and kissing you for the last time last night was so painful.. I just kept thinking I hope he's feeling my touch and hearing me say he was my son and that I loved him.. But I know he knows!! Spawn! now go play with Buddy.. I'm sure he'll be less annoyed this time.. I hope you are both sharing treats and running together.. I miss you both. Two little wolves and #Wolfpack Family in heaven.. Be good spawnie till I see you again.. And don't worry about Lucy, we are gonna take care of her till its time for her to see you. #RIPSpawn WV Part 1

A photo posted by Wilmer Valderrama (@wilmervalderrama) on Dec 27, 2015 at 5:20pm PST

Thinking of how loving you were my handsome boy.. I miss you Spawn.. #RIPSpawn Part 2 A photo posted by Wilmer Valderrama (@wilmervalderrama) on Dec 27, 2015 at 9:50pm PST