Katherine Heigl has been left heartbroken after her pet pooch has developed a brain tumour.

The 39-year-old actress has revealed in an emotional video posted to her Those Heavenly Days blog that one of her dogs, named Gracie Lou, has been battling a brain tumour since September.

Katherine posted the video as she revealed she would need to step away from updating her blog whilst she tries to save her pup's life.

In a lengthy caption posted underneath the five-minute clip, she wrote: ''In late September my constant companion Gracie Lou was diagnosed with a brain tumor. Doctors told us that we needed to make an immediate decision about whether to take our chances with brain surgery or let Gracie go. Josh and I decided to give Gracie a shot at survival and opted for the brain surgery.

''Now, several months after the surgery and radiation treatments, we are spending a majority of our time tending to Gracie's post op needs. It has been time consuming, worrisome and often heartbreaking but I am determined to give Gracie everything I've got to help her heal. She has been an incredible source of comfort, companionship, loyalty, love and joy for me from the moment I adopted her and I know in my soul I owe her as much as I can give in return.

''So, something else must give if I am to make Gracie a priority in an already busy, kid filled life. Since I can't really table the whole mothering thing, it is the blog that must take a back seat. Every day brings with it minor but important improvements in Gracie's behavior and health and I am hopeful that by the new year she will be back to her old self and I will be back to sharing all my Heavenly Days inspiration with you!

''Thank you for your continued support, your good wishes and your loyalty. May this holiday season bring you an abundance of peace, joy, love and laughter. See you in 2018! (sic)''

The 'Grey's Anatomy' star - who has Nancy, nine, Adalaide, five, and Joshua, 11 months, with her husband Josh Kelley - also posted the news on Instagram, where she shared snaps of Gracie post-surgery.

She wrote: ''My best buddy Gracie Lou recently went through brain surgery and radiation to try to minimize a giant tumor growing in her brain. I've shared a video and her story on my blog (link in bio) and explain why I need to take a blog break for the next month to devote myself to her care. Anyone who's ever loved a companion animal knows just how much unconditional love, patience, comfort, loyalty, laughter and joy they bring to our lives. Gracie has been all of that and more for me so now I am going to do everything I can to save her! #SavingGrace#thoseheavenlydays thoseheavenlydays.com (sic)''