Kevin Smith Mourns the Death of His Dog (and Frequent Costar) Shecky: 'No Day Is Promised'

The actor and director wrote a moving Instagram tribute to his dog of almost 20 years, who recently died in his sleep

On Friday, Kevin Smith wrote "an obituary I was hoping to never have to write," one for his beloved dog, Shecky.

In a moving Instagram tribute that ran alongside a series of images featuring the actor and his pup, Smith memorialized the dog, who lived for nearly two decades.

"My beloved best friend and faithful canine companion, the sensational Shecky, passed away quietly in her sleep last week," he began. "It is the most devastating loss I've experienced since the death of my Dad (20 years ago this June), because Shecky was a phenomenal fixture on the landscape of my life for nearly 2 decades. For over a third of my 52 years, her plucky personality permeated my existence and my work."

Smith went on to mention that Shecky often joined him on his various podcasts, and even made cameos in his films Tusk, Yoga Hosers, Jay and Silent Bob Reboot, Son-in-Lockdown and more.

"The great @stephengris even immortalized her in the closing credit song from Reboot," he added, " 'Shecky Don't Like It.' "

However, Smith, 52, continued, "it was in my personal life where Shecky featured most prominently. As the Robin to my Batman (or vice versa in her mind), Shecky accompanied me on many adventures and countless walks. Even in her advanced age, she showed no signs of slowing down and no hints of being sick at all: she simply went to sleep Tuesday night and didn't wake up Wednesday morning."

Related: John Mulaney's Dog Petunia Dies: 'Loved You from the First Moment'

Smith — who recently opened up to PEOPLE about his mental health struggles and body dysmorphia — said his family "kept the news from me" until this week, as he's been in Florida taking care of his mom, who was hospitalized, and in New Jersey for some work engagements.

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"I was inconsolable and beyond devastated," he added, "until I realized Sheck imparted an important final life lesson with her departure: No Day is Promised. So never take anyone you love (or even like) for granted, Kids: they may not be there when you get home."

He concluded his memorial post, "With the exception of my Mom, my wife, and my kid, nobody will ever love me more than this tiny titan adored me. And I assure you, the feeling was mutual. For the rest of my days, there will always be a miniature dachshund-sized hole in my heart that will never be filled. Losing my best friend and little Baby Dog has wrecked me -but I was lucky to have known her at all."

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