Arnold Turner / BMI / Invision/AP 1 / 9
Arnold Turner / BMI / Invision/AP 1 / 9

It's no secret that Mariah Carey and Nick Cannon's marriage has been crumbling for months.

But while the couple have reportedly agreed on how to split up their fortunes (they'll honor the terms of their prenup) as well as custody of 3-year-old twins Moroccan and Monroe (they'll share custody), they're now fighting over their pets.

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U.K. newspaper The Sunday Express reports that the singer, 44, and the "America's Got Talent" host, 34, cannot agree on who should get custody of their eight Jack Russell terriers: The Good Reverend Pow Jackson, Mutley P. Gore Jackson The Third, Jill E. Beans, Pipitty Jackson, Cha, Jackie Lambchops, JJ and Squeak E. Beans.

Mariah -- who Us Weekly says spends $46,000 a year on spa treatments for her pooches -- wants custody of all eight dogs, reports the Sunday Express, while Nick claims to have a "special bond" with two in particular -- The Good Reverend Pow Jackson and Mutley P. Gore Jackson The Third -- and wants sole custody of them as well as visitation rights with the others, says the newspaper's source.

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"The dog issue is a real stumbling block in negotiations between both their sets of attorneys with Mariah insisting she doesn't want to split the pets up," a legal source close to the case told the paper.

A friend of Mariah's explained to the paper that Mariah has favored the particular breed of dog since she was a girl and that most of the animals have been rescued from shelters.

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"Since they've been married, Nick has come to love their pooches too and, even if he ends up with a couple of them, he will sorely miss the rest and hopes to see them when he can," adds the friend.