Oldest dog hates chemotherapy

So, I'm going to post about this now. It's not exceptionally funny, and it's a long ass post, and it's here more for my benefit than anything else.

About a month ago, Otis - our first dog, a Heeler/Shepherd/mystery-meat mix - stopped eating with enthusiasm. Probably it happened some time before that, but it's not always easy to tell when a dog downgrades from ravenous eating to only very hungry eating.

We'd just taken in a new dog and he seemed a little pissed off about this, and he's always been a little snobbish about kibble, so we initially thought it was just a little protest at the general state of affairs. Then he stopped eating. He'd pick up food, look a little worried, and then let it fall out of his mouth again.

So we figured he was painful. He chews on bones aggressively and he'd never had a good dental exam, so we figured he had a broken and/or rotten tooth. I took him in to the vet to get him scheduled for a cleaning. He's six-and-a-half years old and we're doing all right in the money department right now, so I ordered the most extensive (which is to say, the senior) pre-anesthetic chemistry panel for him. Out of curiosity as much as anything else, and I'm a big fan of blood screens for early detection.

This was on a Thursday. The chemistry panel came back on Friday with a high total calcium. I'm a vet student, so I know the list of differentials for hypercalcemia - tumor, tumor, and spurious test result. Naturally we hoped for the latter.

Otis's dental was scheduled for that Monday. Over the weekend, we tried various foods on him. Thursday he ate cottage cheese. Friday he wouldn't eat cottage cheese, but he ate sliced ham and turkey. Saturday he ate the turkey, but not the ham. By Sunday he wouldn't eat anything except for a few crackers.

Monday's dental didn't turn up anything except a remarkably healthy set of teeth and gums for a dog who gets virtually no dental care save avid chewing. We took survey radiographs to look for tumors, since nothing was apparent on the outside. The vet took a look, said she couldn't find anything except a suspicious looking length of intestine. We scheduled him for an abdominal ultrasound at another hospital the following day. I took the radiographs with me to take to the next clinic.

That afternoon I had nothing to do, so I went over to the vet school to look at the films for myself. I'd just put them up on a view board when one of my classmates walked up and pointed at the chest film. Sure enough, there was an opacity right in front of the little guy's heart.

This is not so good. There are two types of tumors that are likely to show up there that might cause elevated serum calcium: one is lymphoma, the other is thymoma.

Lymphoma is a tumor of white blood cells (lymphocytes, to be specific). When it is in the thorax, it is almost always a T-lymphocyte tumor, and these do not respond well to therapy. Less than a third of lymphomas cause a high calcium in a dog.

Thymoma is a tumor of the thymus, the organ responsible for making T-lymphocytes. The thymus sits in front of the heart and is large when animals are very young, but regresses with age, though there are vestigial remnants of it sitting around. This type of tumor is not as common as lymphoma - not even at this location, which is an uncommon lymphoma site - but it has a couple of features that made me think that the mass might be a thymoma and not lymphoma. It was seated near the sternum (thymomas are more commonly - though not always - found near the sternum while lymphomas are usually - though not always - found nearer the spine) and thymomas are more likely to raise calcium levels than is lymphoma. Treatment of thymoma is a dangerous intrathoracic surgery, but animals who make it through the surgery usually live for a couple of years or more. Treatment of lymphoma is chemotherapy, and prognosis for treatment in this location is a couple to a few months of survival, at best.

So, I took Otis to his ultrasound appointment the next day. They went ahead and looked at his abdomen and took more radiographs of his chest, making it clearer that the mass what we already thought it was. On ultrasound, its appearance was more consistent with a thymoma than a lymphoma, but this was by no means diagnostic. And Otis had some lymph nodes that were a little large. We aspirated the lymph nodes and sent the samples over to the vet school to be evaluated.

It was - it is - lymphoma. Mediastinal lymphoma. Not the "good" kind (dogs with lymphoma that is restricted to peripheral nodes respond well to chemotherapy and can live for years after treatment). Otis started chemotherapy that Thursday, a week after he started spitting out his food. He took the first week's treatment (IV doxorubicin that day and daily prednisone) pretty well, with a day or two of feeling sick and then coming back around and eating well, playing, howling a bit (his newest trick is howling on command), wrestling with his dog.

The second week of treatment has not gone as well. The cyclophasphamide wiped out his GI tract - which always has been a sensitive one. Vomiting, diarrhea, anorexia, and by Friday night his gut stopped moving and blew up with gas so fast that I took him in to have radiographs taken just to make sure he wasn't blocked (which has happened to him before), though I figured , especially after giving him a rectal exam, that it was just unbelievable gas. Which it was. I had to roll down the windows on the way home from the clinic in the rain.

Now, five days later, he's just starting to willingly eat a little bit of food again. He's due for his next treatment tomorrow, but I don't know yet if we're going to carry through with it. As I said, his prognosis is not good, and he's probably not even going to survive the full 19 weeks of chemotherapy. The idea in starting the treatment was just to get him a good last summer before he goes, but if this is going to be his response to chemo, it's not going to be a good summer, and I'd rather shoot for a couple of good weeks before the hypercalcemia comes back and we have to put him down than two months of force-feeding and subcutaneous fluids. There also is the option of continuing with the prednisone alone (which will help with the calcium for a little while even after the tumor is resistant to it) or of continuing just on the prednisone and doxorubicin (the drug he didn't respond too badly to).

Anyway, this is a long read. If you got this far, you probably should get back to work. I just felt like throwing this up here, since I've actually got a few slack hours when I don't have to study for an exam or give Otis his nursing care. (He's sleeping right now, which he hasn't done a whole lot because of how he's been feeling and because the antinausea drug we've been giving him makes him nervous and jittery; I'm thinking about trying to get him some valium, which will take the edge off of the nausea and off his general anxiety.)

Spring's here and it is beautiful out here on the porch.