Maggie is a beautiful 4 year old Australian Shepard who presented to us last summer with a vague history of “not being herself”. According to the owners, Maggie had been listless and not willing to play as she usually does for about a week prior to coming in. Her appetite was decreased and it appeared as if her thirst had increased. She had been vomiting after drinking for the past few days as well.
On Presentation, Maggie was subdued but responsive. Her physical exam revealed mild dental tartar, slightly enlarged sub mandibular lymph nodes and no other gross abnormalities. With this history, almost anything could be wrong with Maggie. We began our diagnostics with a comprehensive blood profile and urinaylsis. The blood tests were essentially normal with the exception of an elevated calcium level. Urine tests were normal as well. Elevated calcium levels can be associated with exposure to certain rodent baits (those containing vitamin D3 or Cholecalcipherol), kidney failure, parathyroid tumors and certain types of cancer including perianal gland adenocarcinoma and lymphosarcoma. Based on these findings, we decided to submit an aspirate from the enlarged lymph node (looking for cancer) as well as take radiographs of the chest and belly (looking for other sources of cancer). The cytology would not return for 24 hours, but we did not want to leave Maggie with the high levels of circulating calcium as they can be toxic to the kidneys and lead to kidney failure.
Maggie was started on intravenous saline solution along with corticosteroids in hopes of bringing the calcium down. Radiographs were taken and found to be normal. By the next day, Maggie’s calcium was down to normal and she seemed to be feeling better. The cytology report came back from the lab and was suggestive of lymphosarcoma (cancer of the white blood cell known as the lymphocyte) but the pathologists could not commit to the diagnosis for certain. Given Maggie’s young age, we did not want to start any chemotherapy without a definitive diagnosis. Therefore, we anesthetized her and removed her sub-mandibular lymph node and sent it to the lab for analysis. During the ensuing 3 days, while we waited for the report, Maggie continued to do well in the hospital.
When we got the biopsy results back, the initial reports did not show cancer. Since this was inconsistent with our clinical findings, we spoke to the pathologists and had them apply special immuno-histochemical stains to the specimens to help them find the cancer cells. With the aid of the new stains, the pathologists were able to confirm that Maggie did, indeed have Lymphosarcoma. There are two main types of lymphocytes in the body, the B-lymphocyte, which is responsible for creating antibodies to fight off bacteria and other invaders, and the T-Lymphocyte, which is responsible for assisting in other immune system functions. Maggie’s cancer arose from the T-lymphocytes which tend to form less easy to identify tumors compared to the B cells.
On average, dogs can survive 10 to 12 months of good quality life with drug therapy for this disease. Therefore, we started Maggie on a course of chemotherapy developed at the University of Wisconsin, which involves the administration of 4 different drugs at prescribed intervals. Initially, the treatments are given weekly and after a few months we spread them out to biweekly. Each drug has a different list of possible side effects and each pet responds to them differently. Maggie tolerated the drugs pretty well, although there were some issues with vomiting and diarrhea we have had to deal with (which are common side effects of these drugs). We treated Maggie without major incident for 9 weeks and then she presented with enlarged lymph nodes again. This is an indication that the cancer had returned. When a pet falls out of cancer remission, we have to institute a new protocol to attempt to bring about another remission. At this point, we sent Maggie to see an oncology specialist. They started a “rescue” protocol involving new drugs and currently she has gone back into remission. She is playing Frisbee and eating gourmet meals prepared by her dedicated owners. We can’t expect to cure Maggie of this cancer, but both she and her owners are happy and grateful for the additional time they have had to spend together.