Hayden announced in October that she was seeking expert help to cope with postpartum depression.
"Hayden Panettiere is voluntarily seeking professional help at a treatment center as she is currently battling postpartum depression," a statement read.
Riley, who joined the cast of "Nashville" earlier this year, said she is now doing "good."
"I texted her and wished her well," the 37-year-old told Us Weekly. "She texted me right back and said, 'I'm awesome, thanks.'"
He added, "hopefully she will be back on the set soon."
In September, she opened up about suffering from postpartum depression, and even offered support to others.
"You're not alone or crazy, ladies!" she wrote on questionnaire for Us Weekly.
The 26-year-old's character on "Nashville," Juliette Barnes, coincidentally has also been battling the condition onscreen.
"It's something a lot of women experience," she said on "Live! With Kelly and Michael."
"When [you are told] about postpartum depression, you think it's 'I feel negative feelings towards my child; I want to injure or hurt my child,'" she continued.
"I've never, ever had those feelings. Some women do, but you don't realize how broad of a spectrum you can really experience that on."