Halsey is mourning the death of their five-year-old dog Jagger, sharing a heartbreaking message and describing him as their “first love.”

The 27-year-old singer, who adopted their furry friend in early 2017 when he was just “a weeks old,” revealed that Jagger suffered a “progressive condition” called Myelomalacia.

Halsey wrote, “Before I had a dog of my own, I would hear people mourn their pets and think ‘it’s just a dog…’ well I couldn’t have been more wrong.”

“I sometimes thought about him passing. How would it feel? Well he’d be old and rickety and grumpy by then. We’d spend the last few years giving him extra ice cream and lazy sunbathing days that he loved when he was too old to run in circles. I knew it would hurt and I feared it immensely, but I was at peace that we’d have many more years together and he’d have a long good life,” the singer shared.

Halsey says that Jagger’s condition became worse “within 3 days,” explaining that Myelomalacia is “sudden and uncommon and unfair with a catastrophic prognosis.”

“My beautiful baby boy went from chasing imaginary birds around the yard and laying in my lap turning his ears up at the sounds of Sesame Street, to having paralysis spread through his body by the hour,” Halsey continued, “Every single person who had the privilege of meeting jagger will never forget him. He was that special.”

The musician took a moment to give some advice to those who are not pet owners, “If you’re reading this and you don’t have a pet, you might be thinking ‘it’s just a dog.’ Like I maybe used to. But I can tell you you’re wrong.”