Can I take my dog swimming while having cancer?

My 14 year old Pit Bull just got diagnosed with cancer 2 days ago. I'm not going to put her through chemo/radiation, but I am going the holistic route. My question, for now, is, can I still take her swimming at the dog beach? She absolutely loves to swim, and since she has arthritis, it's great on her joints. But I don't want to put her in harm if it's now going to be too much for her. Any help will be appreciated.