Hemoplasma infections are erythrocytic infections in both cats and dogs but are more common, and more often associated with disease, in cats. Mycoplasma haemofelis is the most pathogenic species in cats, causing hemolytic anemia and fever in immunocompetent hosts, whereas Mycoplasma haemocanis usually only results in hemolytic anemia in splenectomized or immunocompromised dogs. Diagnosis is by polymerase chain reaction on blood samples because cytology is unreliable. Prompt treatment of clinical disease with supportive care and at least 2 weeks of doxycycline is usually successful. Transmission pathways have not been confirmed, but indirect, via vectors, and direct via bites/fights/predation are likely.