This will be long - giving my dog's health history, habits, meds, and personality, and any other info that might help anyone reading this to understand what's going on with him.
My sweet dog is a male 8-9 year old poodle-mix named Jasper, has degenerative disc dz and ruptured a lumbar disc in July 2008; uses doggie wheelchair, which he loves; was dxed with autoimmune poyarthritis before I adopted him from a rescue two and a half years ago. Meds - prednisone 5 mg qd for arthritis, Atopica 50 mg qod (off label use for arthritis; he had been on pred 10-15 mg qd, and decreasing it would make his s/s worse, so vet added Atopica - this was an informed decision), diazepam 2.5 mg bid for bladder, and famotidine (1/2 OTC tablet bid). He has had frequent bouts of diarrhea - used to happen every two weeks (from the time of his disc rupturing) and now occur about every 6-8 months. He has had frequent UTI's due to paralysis; these have decreased from one every two months to two in the past calendar year.
Due to the pred, he does have some Cushing's type s/s, but has never "complained" and has always been cheerful - he still is. He has a great appetite, but is not overweight - I watch his intake and try to keep his weight consistently at 20 pounds.
In Aug 2009, he had bilateral cataract surgery - his cataracts had been so bad that he was essentially blind. since then, his corneas have been very dry and he takes three eye meds a day - tacrolimus for tear production, flurbiprofen (anti-inflammatory), and Ocusol A.
Recently, I noticed that when he swallows(not while eating but during the normal course of things like we humans do), there is sometimes a dry "clicking" sound and that once in a while an indrawn breath will sound like a sob (for lack of a better description) but he has not been in any apparent distress. Xray today indicated dorsal deviation of trachea due to a large cranial mediastinal mass. The vet has sent the xray to a specialist for review. Labs today - a mild alk phos elevation; no hypercalcemia. I will have to ask her if she drew a CBC.. She did not mention lymphoma to me (she knows that I'm extremely emotional about Jasper), but the mass appeared to have the same density as a lymph node when seen on xray; its outline was irregular as well, which I know usually means malignancy.
I have literally spent 6 or 7 hours tonight online, researching Jasper's xray findings. the only thing that comes up is lymphoma. And I'm scared to death! I know the prognosis is not good.
Jasper really is my only companion - all three of my parents have died recently, and my son and grandson live out of State, so I am bascially alone. He goes to work with me every day, where he acts as a therapy dog for my (human) patients. He is a cheerful, gentle, playful, friendly dog who easily wins people's hearts. He seems to work especially well with anxious people - his presence calms them.
I hope and pray that he does not have lymphoma or any other cancer. What is the differential diagnosis for a canine mediastinal mass - probably an enlarged lymph node? Can it be due to immune processes, medication side effects, valley fever (we live in Arizona) or any other kind of infection?
Thanks to those who took the time to read such a lengthy post.