Animal lover Beth Ostrosky Stern penned a heart-rending Instagram post Thursday to the rescue dog that prosecutors say was beaten to death on Long Island, telling the tragic pooch, “What happened to you was unimaginable.”

“Dear Tucker,” the post begins, addressing the first of the three dogs that were allegedly beaten — two fatally — one after another after being adopted by Mineola newlyweds Ellie Knoller and his wife Jessica Kuncman.

“I am literally sick,” she wrote in the post. “There is no excuse for cruel, senseless inhumane actions like this. as a society, we CANNOT tolerate the murder of innocent animals. My heart is literally broken.”

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Tucker, a male shepherd mix, was the first dog the couple adopted, prosecutors say. He died of a kidney rupture as a result of what prosecutors say was Knoller’s “blunt force trauma to the dog” just nine days after his adoption from the North Shore Animal League.

Stern, who is married to shock jock Howard Stern, is a devoted advocate and spokeswoman for the shelter.

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“Rescued from terrible conditions in Virginia, the incredible rescuers from North Shore Animal League America brought you back to the safety of our shelter, where we nurtured you until you were ready to be adopted,” Stern wrote.

“Well, you were adopted. To MONSTERS. Imagine the fear and terror and confusion and pain Tucker and the other 2 defenseless dogs experienced,” she wrote.

“You, Tucker, and the other 2 innocent lives will be in my thoughts forever,” she wrote.

She ends the post promising “to do everything I can [to] make sure something like this never happens again.”

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The couple pleaded not guilty to charges of over-driving, torturing and injuring animals Wednesday in Nassau County Court. Knoller faces an additional top charge of felony aggravated cruelty to animals.

This article originally appeared in the New York Post.