When Jake Gyllenhaal and Kirsten Dunst were young Hollywood’s "It Couple," gossip columns and tabloids buzzed with "They’re just like us!" tidbits and photos of the pair walking their adopted German shepherd, Atticus. Now, three years after their breakup, Gyllenhaal is reportedly planning a wedding to Reese Witherspoon — with Atticus as the ring bearer.

It’s one thing when your ex has moved on to someone else, but how much deeper does it cut when his new woman is photographed walking the dog you adopted together?  

As Americans increasingly marry and have children later in life, the numbers of couples with pets have risen dramatically, and with those shared pets comes the question: what happens when you break up? The American Academy of Matrimonial Lawyers reported that a quarter of its members had seen an increase in the number of divorce cases involving pets — the majority of them dogs, but also horses, birds, and boa constrictors — such as the 2000 case of a California couple that spent more than $100,000 fighting over a pointer-greyhound cross named Gigi. "I had a litigation case involving a very high-end parrot," says James Hennenhoefer, president of the AAML, "and the allegation was that the man smoked pot in the presence of the parrot when it would visit him and the parrot would come back under the influence. So there was a discussion of whether it was in the parrot’s best interest to visit the pot-smoking dad."

Many couples don’t have formal agreements about who gets the pets, but that discussion can be as fraught as any that led to the breakup. When Ryan Devlin and his wife separated after five years of marriage, "She cried like I’ve never seen anyone cry in my life when I said ‘I’m taking the cats,’" he says. "So I decided it wasn’t worth fighting over. But that sucked. I didn’t want to give them up. I love them."  

Most state laws still classify pets a property, much like the TV or your vintage T-shirt collection, but with one key difference: If you and your ex can’t decide on who gets the pet, you can’t liquidate it like you would a car and split the proceeds. "There’s a lot of informal mediation and it’s the rare case that goes to court," says David Favre, a professor at Michigan State University College of Law and editor in chief of animallaw.info, "but some people are so emotionally invested in their pets that there’s no compromise available in the custody issue."