A 12 year old, 38 kg, mix-breed, intact male dog presented with a 20 day history 
of clinical signs consistent with hyperviscosity syndrome secondary to multiple 
myeloma. The dog received three double filtration plasmapheresis treatments on 
day 0, 7 and 22 after presentation. A significant (p<0.05) reduction in serum 
total protein, alpha-2 and gamma globulins was found following each treatment. 
These reductions were accompanied by a complete resolution, although temporary, 
of the clinical signs of hyperviscosity syndrome. The present study reported for 
the first time the use of double filtration plasmapheresis to reduce clinical 
signs of hyperviscosity syndrome in a dog with multiple myeloma.