Capnocytophaga canimorsus is a catalase-positive and oxidase-positive gram-negative bacillus commonly found in dog saliva that is a rare cause of infection in immunocompromised individuals. We report the case of a 70-year-old woman with Waldenström macroglobulinemia treated with ibrutinib and a history of bilateral shoulder arthroplasty and bilateral knee arthroplasty who reported a 1-year history of multi-joint pain and swelling. The patient resides with two pet dogs that often scratch and bite, penetrating the skin, and on culture was found to have Capnocytophaga canimorsus.