Hemolytic anemia in cats: Infectious or immune-mediated? (Proceedings) - Veterinary Healthcare


Hemolytic anemia in cats: Infectious or immune-mediated? (Proceedings)



Generally associated with subclinical disease in cats, hemolytic anemia is a consequence of several human Bartonella spp. infections, including a case of human hemolytic anemia caused by Bartonella henselae. Studies have also demonstrated the intraerythrocytic location of B. henselae in naturally-infected cats. However, an epidemiologic study attempting to correlate various organisms, through the use of PCR assays, with cases of hemolytic anemia found no significant prevalence differences in the healthy cats versus anemic cats with a positive Bartonella PCR assay.


Ehrlichia spp. has been demonstrated to cause clinical signs in cats, including fever, lethargy, inappetence and anemia. The anemia is often classified as non-regenerative. However, because Ehrlichia PCR is not normally part of the battery of infectious disease tests ordered for the cat with hemolytic anemia, it is still not known how much of a role this disease plays.


A non-regenerative anemia is usually the clinicopathologic abnormality in young cats diagnosed with FeLV, but hemolytic anemias have been documented. FeLV antigen testing is therefore recommended for any cat presenting with hemolytic anemia. FIV infectious are nearly always associated with a non-regenerative anemia and likely falls into the category of "anemia of chronic disease" rather than a primary immune-mediated mechanism.

Primary Immune-mediated Disease

There is a subset of cats for which neoplasia, toxins and the majority of infectious diseases have been ruled out, either by infectious disease assays or trial therapies with anti-bacterial agents. These cats only respond to immunosuppressive doses of glucocorticoids and have relapses when dosages are reduced or discontinued. Primary IMHA has been thought to be uncommon in cats, but recent epidemiologic studies and case series suggest. IN one retrospective study, approximately 60% of cats with anemia had no identifiable infectious or neoplastic cause for their anemia. New techniques, such as flow cytometry and anti-erythrocyte antibody assays, may be helpful in identifying cats with an underlying primary hemolytic anemia.


The most common cause of hemolytic anemia in cats has long thought to be secondary to infectious diseases, neoplasia, and toxins. While these infectious and non-infectious diseases should be considered in cats presenting with hemolytic anemia, primary hemolytic anemia may be more common in these cats than historically thought.

Selected references

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Bondy PJ Jr, Cohn LA, Tyler JW, Marsh AE. Polymerase chain reaction detection of Cytauxzoon felis from field-collected ticks and sequence analysis of the small subunit and internal transcribed spacer 1 region of the ribosomal RNA gene. J Parasit 2005 (91), 458-61.

Walker DB, Cowell RL. Survival of a domestic cat with naturally acquired cytauxzoonosis. JAVMA 1995 (206), 1363-5.

Stubbs CJ, Holland CJ, Reif JS, et al. Feline ehrlichiosis; literature review and serologic survey. Compend Cont Educ Pract Vet 2000 (22), 307–317.

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Kohn B, Weingart C, Eckmann V, et al. Primary Immune-mediated anemia in 19 cats: diagnosis, therapy and outcome (1998-2004). J Vet Int Med 2005 (20), 159-166.

Ishak AM, Radecki S, Lappin MR. Prevalence of Mycoplasma haemofelis, 'Candidatus Mycoplasma haemominutum', Bartonella species, Ehrlichia species, and Anaplasma phagocytophilum DNA in the blood of cats with anemia. J Fel Med & Surg 2007 (9),1-7.


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