The Case of the Gimpy Goldie
1. Referral:
“Beau” is a 30kg, 12 year old male, neutered Golden Retriever who was presented to ASG with a one day history of lethargy and pain on palpation of the cranial lumbar region. The owner had noticed a gradual decrease in energy and weakness in his pelvic limbs over the past several months, initially attributed to arthritis related to bilateral hip replacement surgery in 2001. Previous history of ulcerative rhinitis treated with Clavamox and Piroxicam in 2008 and GDV surgery in 2009. A cecal gastrointestinal stromal tumor was identified incidentally during the GDV surgery and was completely excised. No current medications. Primary care veterinarian’s lab work performed prior to referral revealed the following abnormalities: albumin 2.2, total protein 12.4, globulin 10.2, calcium 13.9, RBC 4.7, PCV 33.
2. Examination:
On physical examination, Beau has prominent prescapular lymph nodes and a tense cranial abdomen with splenomegaly. He was weak in the pelvic limbs and had difficulty standing. Pain was elicited when the cranial lumbar spine was palpated.
3. Diagnostic Procedures:
Radiographs of the thorax and spine were obtained revealing an expansile lytic bony lesion of the L2 dorsal spinous process. Serum electrophoresis revealed a marked monoclonal gammopathy. The USG was 1.010 with trace proteinuria and no growth on culture. The urine electrophoresis was negative with protein levels too low to test. The bone marrow was infiltrated with 50% well-differentiated plasma cells. The cells were beginning to efface normal cell lines causing mild erythroid and myeloid hypoplasia. Coagulation profile was within normal limits. Abdominal ultrasound revealed rounded liver margins with irregular echotexture, subtle hypoechoic splenic nodules, and mild mesenteric lymphadenopathy. On the liver cytology, 50% of the inflammatory infiltrate were mild to moderately dysplastic plasma cells. In the spleen, these cells accounted for 80% of the nucleated cell population with rare splenic trebeculae or hematopoietic tissue identified. An ionized calcium was 1.97 upon admission (normal 1.25-1.45).
4. Diagnosis:
Based on the lytic bone lesion, the monoclonal gammopathy, the moderate to marked plasma cell hyperplasia and atypia in the liver and spleen, and the 50% infiltration of the marrow with plasma cells, Beau was diagnosed with multiple myeloma.
5. Treatment:
Beau was admitted to the ICU for saline diuresis supplemented with KCl to promote calcium excretion. The recheck ionized calcium 5 hours later was 1.7 and remained stable overnight. Buprenex was administered for pain. Pamidronate, a bisphosphonate class of drug, was given IV over 4 hours to decrease osteoclastic activity and decrease bone pain. Dexamethasone 4mg was given IV once. Melphalan chemotherapy was administered orally at 0.1mg/kg PO q 24 hr. Beau did well overnight and his appetite returned. His weakness persisted, but he was walking with sling assistance. Ionzied calcum that morning was 1.52. He was discharged from the hospital with instruction to continue Melphalan oral chemotherapy and start Prednisolone 1mg/kg PO q 24 hr. Tramadol 100mg PO q 12hr was prescribed for pain.
6. Follow-Up:
At the time of the first recheck 10 days later, Beau was doing well at home: normal activity and appetite. The owner no longer needed to use the sling and he was only mildly weak in the pelvic limbs. The owner noticed intermittent back pain that was responsive to an additional dose of Tramadol. Blood tests revealed a 40% reduction in the globulin level to 6.3. The albumin was improved to 2.6. A mild non-regenerative anemia was present (RBC 4.1, PCV 30). The liver enzymes were mildly elevated (ALT 173 and ALP 204). Ionized calcium was normal (1.08). The owner was instructed to decrease the Melphalan dose by 50% and to decrease the prednisone dose by 25%.
7. Discussion:
The criteria for the diagnosis of multiple myeloma include Bence Jones proteinuria, monoclonal gammopathy, lytic bone lesions and >20% plasma cell infiltration in the bone marrow with 2 of 4 criteria being necessary to confirm the diagnosis. The Melphalan/Prednisolone treatment has a 90% response rate in dogs with a reported median survival time of 540 days. Hypercalcemia, Bence Jones proteinuria, and lytic bone lesions are negative prognostic factors. The Pamidronate can be continued monthly to alleviate pain as well as improve the health of the affected bone. Palliative radiation could be also considered for the L2 dorsal spinous process lesion as needed.
8. Recovery:
Beau presented to his primary care veterinarian a month later and the globulin level was normal. His liver enzymes were increased (ALT 248, ALP 366) and he had a mature neutrophilia and lymphopenia. Recommended continuing Melphalan chemotherapy and monitoring the CBC for myelosuppression. Recommend decreasing the prednisone dose by 25% and tapering over the next 3 months. Serum chemistry will be evaluated for recurrence of the hypercalcemia and hyperglobulinemia. Radiographic improvement of the lytic lesion can be delayed for months and may only partially improve.
by Mary K. Blake, DVM
Practice Limited to Medical Oncology and Radiation Consultation and Referral
*Photo of Golden Retriever is not “Beau.”