My dog's anal gland cancer spread to lymph nodes. How long will he live?

I'm so sorry to hear about Reshmk's diagnosis. There are many variables that come into play when discussing life expectancy, and unfortunately not all of them can be predicted. Anal gland adenocarcinoma can be locally invasive and sometimes the tumor gets big enough to cause significant pain and discomfort for the dog, or can grow to a size that inhibits normal/comfortable defecation. So, sometimes the limiting factor is a determination of quality of life based on the direct activity of the mass and its effects on a dog's comfort level. Other times, we can have less direct symptoms related to the cancer, either due to metastasis and those effects on the organs, or due to hypercalcemia, which is a common secondary issue with this type of cancer. Hypercalcemia can lead to excessive thirst and urination most commonly, or can cause GI upset, vomiting, and decreased appetite. These symptoms of hypercalcemia can sometimes initially be managed with medications, but often decisions about quality of life are made when the dog feels ill and medications can no longer control the symptoms. The best one to offer input on a specific survival time would be your vet, who knows the details with Reshmk's cancer and how aggressive it appears, but with the knowledge that it has already been diagnosed in the regional lymph nodes, I would anticipate a survival time of 6 months or less, as the general survival time even with surgery, radiation, and chemotherapy is still less than 3 years. I'm so sorry again about this sad news. I hope this helps.