Shannen Doherty admits her chemotherapy treatment is taking its toll.

The former 'Beverly Hills, 90210' actress - who was diagnosed with breast cancer in February 2015 and revealed recently that it has since been detected in her lymph nodes also - has taken to Instagram to thank her fans for their support and to post a sweet photo of her beloved dog Bowie.

She wrote: ''Each persons cancer journey is different. For me, chemo has been terrible and believe me, we have tried almost everything.

''So days like this have become a bit of the norm. I'm learning that it's ok to fall into bed and give in to the exhaustion or nausea or aches. I've learned a lot of that thru all the beautiful people who have shared their personal stories with me right here on Instagram.

''Thank you. Btw, it doesn't hurt to have #msbowie comfort me So back to my nap. Thank you for your prayers, well wishes and stories. They help so much. #blessed by #mamarosa. (sic)''

This comes shortly after Shannen claimed her dog was the first to detect her breast cancer.

The 45-year-old actress believes her pet pooch Bowie knew something was wrong long before her diagnosis as she kept ''obsessively'' sniffing her right breast.

Shannen explained: ''She [Bowie] would obsessively sniff right here on my right side for a long time before. So, it made sense when I got diagnosed.''

Meanwhile, Shannen also recently opened up about her struggles over the last few months.

She said: ''I had breast cancer that spread to the lymph nodes, and from one of my surgeries we discovered that some of the cancer cells might have actually gone out of the lymph nodes.

''So for that reason, we are doing chemo, and then after chemo, I'll do radiation.''